Evolutionary Characteristics of Floor Plan Design in Public Rental Housing in Korean New Towns: Case Studies from 1990 to 2010

Abstract

Since the 1980s, South Korea has continuously supplied public rental housing alongside the development of new towns. However, systematic studies examining the relationship between qualitative changes in floor plan design and the institutional factors influencing them remain limited. This study is based on the premise that floor plans in public rental housing are not merely the result of design improvements, but are structurally shaped by legal and institutional frameworks. It systematically analyzes changes in floor plan types and planning elements according to development periods and housing sizes. To achieve this, this study examines public rental housing supplied in Korean new towns from the 1990s to the 2010s, classifying floor plan types by period and housing size and analyzing their planning characteristics. The analysis focuses on the composition and arrangement of interior spaces, the size of each space, bay structure, and aspect ratio. A comparative analysis further examines the relationship between floor plan changes and relevant laws and institutional frameworks. The results show that floor plan configurations evolved in distinct phases in response to institutional changes and housing size differentiation. In the 1990s, standardized one-bay layouts with integrated living and sleeping spaces were predominant under strict regulatory conditions, including spatial dimension constraints. In the 2000s, following the legalization of balcony extensions, floor plans diversified into two-bay and three-bay configurations. In the 2010s, floor plan types became increasingly diversified and complex under the influence of district unit plans and detailed design guidelines issued by public agencies. In terms of housing size, smaller units (around 20 m²) maintained simplified one-room configurations, while medium-sized units (around 30–40 m²) exhibited a clear transition from integrated to functionally separated layouts, and larger units (around 50 m²) showed a significant increase in spatial diversity and variation in layout composition. These findings indicate that floor plan evolution is not a linear process of design improvement, but a structurally conditioned transformation shaped by regulatory frameworks, institutional changes, and path dependency. The persistence and gradual modification of earlier standardized layouts suggest that floor plan configurations are continuously reproduced and adapted within institutional constraints. By empirically identifying the structural relationship between institutional frameworks and floor plan design, this study reveals the mechanisms through which institutional conditions shape housing design. Furthermore, it contributes to an interdisciplinary understanding that integrates architecture, urban planning, and housing policy, and provides important implications for design guidelines and policy development aimed at improving the quality of public rental housing.

1. Introduction

The Republic of Korea began supplying permanent rental housing following the announcement of the “Two Million Housing Construction Plan” in 1989, as part of efforts to stabilize housing for low- and middle-income households. In addition to permanent rental housing, public rental housing has been divided into various types, such as national rental housing, Happy Housing, and long-term rental housing, and has been built and supplied as apartment complexes in new towns mainly developed by the public, such as the Seongnam Bundang Housing Development District [1].

Public rental housing in Korea has been positively evaluated for the past 30 years in terms of a stable housing tool for socially vulnerable groups and low- and middle-income households, and the rapid large-scale supply of apartment complexes. As the focus is on the quantitative supply of public rental housing, limitations have also been steadily raised that the plan did not fully reflect changes in demand, such as changing family structures, lifestyles, and individual housing preferences [2]. These problems have resulted in an increase in the vacancy rate of public rental housing over time, especially in some types and sizes of housing [3,4].

This mismatch between supply and demand is largely attributed to the fact that the spatial composition and floor plans of housing units did not adequately reflect the needs of actual residents, as well as the location and external conditions of the complex [5]. In particular, the floor plan of public rental housing mainly created in new cities seems to have tended to be uniform in design according to certain standards, such as planning standards of public institutions and district unit plans of the development district. As a result of prioritizing rapid supply and cost reduction in public rental housing, there may have been limitations in reflecting diverse household types and lifestyles. This legal and institutional framework made it difficult to introduce variability between generations or customized floor plans, and as a result, some housing types became separated from the needs of end-users and led to an increase in the vacancy rate [3,4].

Private sector apartments, on the other hand, have attempted to diversify and differentiate the floor plan composition through relatively flexible planning and marketing strategies while complying with related laws such as the Building Act and the Regulations on Housing Construction Standards. However, public rental housing has been designed according to specific and rigid planning guidelines such as the “LH Architectural Design Guidelines”, which may have limited the flexibility and diversity of floor plans. In particular, public rental housing was placed under rigid constraints in planning the minimum area of unit households, composition by room, circulation standards, and arrangement of main buildings, which acted as a factor that hindered the possibility of change in floor plan and design flexibility [5].

Systems such as district unit planning and architectural review procedures also served as the background for further deepening the difference in design between the private and public sectors. Since the increase in unsold housing units in the early 2000s, private sector apartments have strengthened user-oriented differentiation strategies in floor plan and external space planning through the branding of apartment complexes, and changes that reflect consumer needs have been continuously made. In contrast, because the achievement of quantitative supply targets was prioritized in public rental housing, improvements in the quality of spatial planning tended to be relatively secondary. In this context, the plan for public rental housing has been centered on standardization within an institutional framework and securing the efficiency of construction costs rather than a design approach to improving the quality of housing, and as a result, the planning gap in the private sector has widened. In this context, empirical studies that examine how the floor plans of public rental housing have been shaped and evolved in response to changing social demands and institutional contexts remain limited.

Therefore, this study aims to examine the evolution of floor plan design in public rental housing in Korean new towns over the past 30 years and analyze how these changes have been influenced by relevant legal and institutional frameworks. To achieve this objective, this study addresses the following research questions:

(1)

How have the floor plan types of public rental housing evolved over time in Korean new towns?

(2)

What are the key characteristics of floor plan design according to housing size?

(3)

How have legal and institutional frameworks influenced these changes in floor plan design?

Based on these research questions, this study is guided by the following analytical assumptions. First, floor plan configurations in public rental housing tend to vary systematically according to development period and housing size. Second, these variations are closely associated with institutional frameworks, including legal regulations, planning systems, and public housing design guidelines. Third, the evolution of floor plan design can be understood not merely as the result of design innovation or designers’ autonomous decisions, but as a structurally conditioned process shaped by institutional factors.

In this context, this study is distinguished from previous research in that it seeks to clarify the structural relationship between design autonomy and institutional rigidity. The findings of this study can serve as a foundational reference for improving institutional frameworks and establishing related standards to enhance the quality of spatial planning in public rental housing. Furthermore, the findings are expected to provide useful insights for housing policy development in Asian developing countries where public rental housing programs are being expanded.

2. Literature Review

2.1. Policy and Institutional Framework of Public Rental Housing

Public rental housing refers to housing built, purchased, and managed by the state, local governments, or public institutions, and supplied at low rents to households below a certain income level or to socially vulnerable groups. Public rental housing in South Korea began to be supplied on a large scale with the introduction of permanent rental housing in 1989, primarily in new towns such as Bundang and Ilsan, as summarized in

Table 1. Evolution of public rental housing policies and institutional changes in South Korea.

Period	Administration	Key Policies/Plans	Legal and Institutional Changes	Key Policy Features
1988–1993	Roh Tae-woo	Two Million Housing Construction Plan/Plan for 250,000 Permanent Rental Housing Units	Revision of the Building Act	Construction of permanent rental housing in first-generation new towns and large-scale expansion of public rental housing supply
1993–1998	Kim Young-sam	Establishment of the institutional foundation for public rental housing and expansion of long-term rental housing	Revision of the Rental Housing Act and the Housing Act	Diversification of mandatory rental periods and introduction of 50-year public rental housing of various sizes
1998–2003	Kim Dae-jung	Introduction of the National Rental Housing Program/Plan for One Million National Rental Housing Units	Enactment and revision of the Housing Act and the Rental Housing Act; revision of the Building Act	Expansion of the large-scale public rental housing supply
2003–2008	Roh Moo-hyun	Implementation and specification of the One Million National Rental Housing Plan	Enactment of the Special Act on the Construction of National Rental Housing	Expansion of target groups for public rental housing (e.g., middle-income households, newlyweds)
2008–2013	Lee Myung-bak	Full-scale implementation of the Bogeumjari Housing Policy	Enactment of the Special Act on the Construction of Bogeumjari Housing	Introduction of diverse public rental housing types (e.g., 10-year rental housing, long-term jeonse housing)
2013–2017	Park Geun-hye	Expansion of target groups for public rental housing/Happy Housing Program	Enactment of the Special Act on Public Housing Construction	Expansion of supply targets to include university students and young adults

. Since then, public rental housing policies have evolved across different administrations [6,7].

Public rental housing in Korea has developed in accordance with these policy changes and related legal and institutional frameworks. Rather than being shaped by a single policy direction, the supply system has evolved through a series of institutional transformations [8], which have significantly influenced not only the planning of housing complexes but also the floor plan design of individual housing units.

Since the introduction of permanent rental housing in 1989, public rental housing policies have gradually expanded in terms of supply scale, target groups, and housing types. In the early stage, policies primarily focused on the quantitative expansion of housing supply for low-income households. Over time, however, the target groups expanded to include young people and newlyweds, accompanied by increasing diversification in housing types.

Along with these policy changes, related legal and institutional frameworks have been continuously enacted and revised. Major laws, including the Housing Act, the Rental Housing Act, and the Building Act, have been amended to support the expansion and diversification of public rental housing. In particular, changes in building regulations—such as the relaxation of standards related to building spacing and height—have enabled greater flexibility in floor plan design [2,9]. Furthermore, the introduction of various types of public rental housing, such as national rental housing, long-term rental housing, and Happy Housing, has contributed to the diversification of spatial configurations and floor plan types. These policy and institutional changes are not merely administrative adjustments but have functioned as key factors in structurally shaping housing forms [10].

Therefore, the development of public rental housing in Korea can be understood as a process in which policy and institutional frameworks have progressively shaped housing design, demonstrating that these frameworks have played a significant role in influencing the spatial composition and design of public rental housing.

2.2. Studies on the Planning of Public Rental Housing

Previous studies on floor plan design in public rental housing have predominantly examined policy and institutional frameworks or spatial planning elements separately. However, recent research has emphasized that these factors do not operate independently; rather, floor plans are shaped through the complex interaction of institutional regulations, policy frameworks, spatial standards, and cultural factors. Accordingly, there has been a growing recognition of the need for an integrated analytical approach.

Based on this perspective, previous studies on floor plan design in public rental housing can be broadly categorized into three groups: (1) studies focusing on institutional and policy frameworks; (2) studies analyzing spatial configuration and design characteristics; and (3) studies examining user characteristics and housing supply types. These research trends are summarized in

Table 2. Previous studies on floor plan design in public rental housing.

Category	Author(s)	Scope	Main Findings	Implications
Integrated approach	Wang et al. (2025) [11]	China, Japan, Republic of Korea	Proposed an integrated analytical framework considering policy, spatial configuration, and cultural factors	Floor plans are shaped by institutional and cultural interactions
	Deng et al. (2016) [12]	Hong Kong	Developed a “design evolution map” showing long-term transformation	Changes in floor plans reflect institutional responses
Institutional standards	Ozer & Jacoby (2024) [13]	20 countries	Examined how regulations and design guidelines influence floor plans	Design outcomes are structurally determined by standards
	Daniel & Lluis (2024) [14]	Sweden	Analyzed the impact of housing design handbooks	Non-mandatory guidelines strongly influence design
	Kim et al. (2023) [15]	Republic of Korea	Identified limitations of minimum housing standards	The gap between regulations and actual living conditions
Design adequacy	Park & Chai (2020) [16]	Republic of Korea	Evaluated housing standards from a universal design perspective	Need to bridge the gap between standards and real needs
Temporal changes	Yeun et al. (2010) [2]	Daegu, Republic of Korea	Increase in shared spaces; decrease in private rooms	Reflects changes in residential culture
	Kim (2018) [17]	Republic of Korea	Shift from bedroom-centered to living room-centered layouts	Transformation of spatial hierarchy
Policy–spatial relationship	Kim & Roh (2025) [7]	Republic of Korea	Showed policy changes affecting housing layout planning	Direct link between policy and spatial configuration
Housing type comparison	Han & Choi (2019) [18]	Wirye New Town, Republic of Korea	Compared spatial layouts across housing types	Spatial hierarchy reflects socio-economic differences
User characteristics	Kim et al. (2024) [19]	Elderly housing	Identified uniformity issues in studio-type units	Need for diversified housing types

.

First, studies addressing the relationship between institutional frameworks and floor plan design commonly argue that the spatial configuration of public rental housing has been structured not by the autonomous choices of designers, but by legal regulations and policy guidelines. Wang et al. (2025) proposed an integrated analytical framework based on a comparative study of China, Japan, and Korea, demonstrating that the interaction between policy systems and cultural factors influences floor plan formation [11]. Similarly, Deng et al. (2016) analyzed the evolution of public rental housing in Hong Kong and visualized it through a “design evolution map,” explaining that changes in floor plans are outcomes of institutional responses [12]. In addition, Ozer and Jacoby (2024) empirically showed through a cross-national comparison that legal standards and design guidelines function as structural mechanisms that determine spatial configurations [13]. In this context, Daniel and Lluis (2024) analyzed how housing design handbooks in Sweden, although not legally binding, have functioned as de facto design standards and have continuously influenced spatial configurations [14].

In addition, several studies have pointed out the adequacy and limitations of institutional standards. Kim et al. (2023) argued that minimum housing standards fail to sufficiently reflect actual living conditions [15], while Park and Chai (2020) highlighted, from a universal design perspective, that existing standards do not adequately accommodate diverse household characteristics. These studies indicate the existence of a gap between institutional regulations and real-life housing conditions [16].

Meanwhile, studies focusing on temporal changes in floor plan design emphasize the influence of social transformations and evolving residential lifestyles. Yeun et al. (2010) identified an increase in shared spaces and a decrease in private spaces [2], while Kim (2018) observed a shift from bedroom-centered layouts to living room-centered configurations, reflecting a transformation in spatial hierarchy. These findings suggest that floor plans are not merely functional arrangements but also reflect broader changes in social lifestyles [17]. Furthermore, Kim and Roh (2025) demonstrated that policy changes have had a significant impact on the layout of apartment complexes, revealing a direct link between policy and spatial planning [7].

In addition, several studies have examined differences in floor plan configurations according to housing supply types and user characteristics. Recent research, in particular, has demonstrated that the efficiency of community facilities and spatial organization in public rental housing is closely related to the quality of the residential environment, emphasizing the importance of planning that considers spatial functions and usage patterns [20]. Han and Choi (2019) revealed that differences in spatial configurations by supply type are associated with socio-economic class structures [18], while Kim et al. (2024) pointed out the limitations of standardized floor plans in housing for the elderly and highlighted the need for demand-oriented design approaches [19].

Overall, these studies demonstrate that floor plans in public rental housing are shaped through the interaction of various external factors. Recent studies further show that spatial configuration and regional context are closely associated with housing satisfaction and policy outcomes, thereby reaffirming that the interaction between spatial planning and institutional factors plays a critical role in shaping residential environments [21]. In particular, international studies highlight the structural influence of legal systems and design standards on spatial hierarchy, typological fixation, and repetition, while domestic studies provide empirical evidence on spatial changes associated with shifts in residential culture and housing supply types.

However, most existing studies are limited to specific time periods or individual case studies, and there is a lack of research that systematically analyzes the relationship between temporal changes in floor plan design and the broader institutional context. Moreover, the mechanisms through which institutional standards are translated into actual spatial configurations have not been sufficiently examined.

To address these gaps, this study proposes a conceptual framework that explains the evolution of floor plans in public rental housing through the interaction of policy systems, institutional standards, and spatial design. In particular, this framework emphasizes the structural relationship between design autonomy and institutional constraints, and aims to systematically analyze the relationship between temporal changes in floor plans and institutional factors.

3. Methodology

3.1. Research Process

The research was conducted in the following steps.

First, in order to analyze cases of public rental housing by period, the construction periods after 1990 were classified and case study sites were selected. Second, to analyze the characteristics of public rental housing floor plans, an analytical framework was established by deriving planning elements affecting housing unit floor plans from previous studies. Third, the types of public rental housing based on unit floor area by construction period were classified, and the characteristics of floor plan elements for each type were analyzed using the established analytical framework. Fourth, a comparative analysis of floor plan types was conducted according to housing unit size and construction period. In addition, the causes of changes in floor plans were examined through analysis of the related legal systems that influenced floor plan design. Finally, based on the analysis results, the characteristics of changes in public rental housing floor plans were discussed, and key insights into these changes were presented. As shown in Figure 1, the research design of this study outlines the overall process from case selection to institutional analysis.

3.2. Scope and Case Selection of the Study

This study is a case study that examines the evolution of floor plan design in public rental housing over the past three decades, beginning with the introduction of permanent rental housing in 1989. Public rental housing in Korea began to be supplied in earnest with the construction of permanent rental housing in first-generation new towns, and since then, both target groups and policy directions have evolved over time. In the 1990s, permanent rental housing was expanded primarily for socially vulnerable groups, including recipients of basic livelihood support, under the “Two Million Housing Construction Plan”. In the 2000s, the demand base broadened to include middle-income households and newlyweds, with national rental housing becoming the dominant supply type. In the 2010s, customized public rental housing targeting diverse life-cycle groups was actively introduced [22]. Accordingly, this study classifies the development periods of public rental housing into the 1990s, 2000s, and 2010s for analysis.

The case study sites were selected by comprehensively considering the development timing of new town districts, the completion timing of public rental housing, and the scale of housing complexes. The selected sites include Bundang (Seongnam) and Ilsan (Goyang) for the 1990s; Dongtan 1 (Hwaseong), Unjeong (Paju), and Hyangnam (Hwaseong) for the 2000s; and Pangyo (Seongnam) and Byeollae (Namyangju) for the 2010s. A total of 37 housing complexes were selected for analysis.

The case selection criteria of this study are as follows. First, this study focuses on new town development districts where public rental housing is sufficiently concentrated to allow for meaningful comparison of floor plan characteristics across different periods. Second, to ensure consistency in temporal comparison, the analysis is limited to permanent rental housing and national rental housing. Third, only housing complexes with clearly identifiable development periods and completion dates were selected. In contrast, newly introduced housing types, such as Happy Housing, were excluded to maintain consistency across different periods.

Table 3. Case study sites for analysis.

Period	Site	Number of Complexes	Number of Households
1990s	Bundang District, Seongnam	7	9317
	Ilsan District, Goyang	7	3203
	Subtotal	10	12,520
2000s	Dongtan2 District, Hwaseong	5	4752
	Unjeong District, Paju	5	5151
	Hyandnam District, Hwaseong	3	3421
	Subtotal	13	13,324
2010s	Pangyo District, Seongnam	3	4994
	Byeolnae District, Namyangju	11	8781
	Subtotal	14	13,775
	Total	37	39,619

presents the selected new town development districts for each period, along with the number of housing complexes and housing units in each district.

3.3. Analytical Framework

To analyze the characteristics of public rental housing floor plans by period, this study establishes an analytical framework by reviewing planning elements of apartment housing identified in previous studies. Previous research has emphasized various spatial and configurational factors that influence apartment floor plan design.

Based on this review, key analytical items were derived, including the composition and arrangement of spaces within housing units, spatial area and proportion, the width-to-depth ratio of housing units, bay structure, balcony area, and the arrangement of staircases. These elements have been widely used as important variables for explaining spatial organization and floor plan characteristics in residential design.

Among these planning elements, this study identifies the core analytical variables as follows (

Table 4. Apartment floor plan analysis items in previous studies.

Floor Plan Elements	1 1	2 2	3 3	4 4	5 5	Selected Items
Spatial composition and arrangement	O 6		O	O	O	◎ 7
Width-to-depth ratio	O		O	O		◎
Bay structure			O	O	O	◎
Balcony area and number	O
Staircase layout		O

¹ Lee, J.H. et al. (2010) [23], ² Kim, H.B. (2015) [24], ³ Choi. I.J. et al. (2008) [9], ⁴ Liu, L. (2013) [25], ⁵ Choi, J.W. et al. (2016) [26], ⁶ “O” indicates papers in which the planning element was applied as an analytical framework in the referenced literature, ⁷ “◎” indicates the planning elements applied in this study.

). With regard to spatial composition within housing units, the composition and arrangement of spaces, as well as space area and proportion, are selected as analytical items. In terms of overall plan configuration, bay structure and the width-to-depth ratio are selected as primary analytical variables. The analytical framework is illustrated in Figure 2, providing a visual representation of the relationships among the analytical elements.

4. Results and Analysis

4.1. Analysis of Floor Plan Characteristics of Public Rental Housing by Period

4.1.1. Characteristics of Public Rental Housing Floor Plans in the 1990s

As shown in

Table 5. Overview of public rental housing floor plan types in the 1990s.

Category	Type	Unit Floor Area (m2)	Number of Households	Ratio (%)	Number of Complexes	Remarks
≥20 m2 < 30 m2	20A	26	1264	10.28	1
	20B	26	2086	16.96	4
	Subtotal		3350
≥30 m2 < 40 m2	30A	31, 35, 36, 37, 38, 39	6051	49.20	9
	30B	35, 36	269	2.19	2	End unit
	30C	39	399	3.24	2
	Subtotal		1719
≥40 m2 < 50 m2	40A	41, 42	1306	10.62	4
	40B	42	420	3.41	1
	40C	42	60	0.49	1	Staircase type
	40D	49	445	3.62	2
	Subtotal

, public rental housing in the 1990s was primarily composed of small-sized units ranging from 26 m² to 49 m². The floor plan typologies can be categorized into three size groups—20 m², 30 m², and 40 m²—with two, three, and four subtypes, respectively. Among these, the 30 m² units account for approximately 54.7% of the total, representing the largest proportion, which indicates that early public rental housing supply was predominantly focused on small-sized units.

The 20 m² units are composed of a combined bedroom and living room, an additional bedroom, a kitchen and dining area, a bathroom, and a balcony. These units are further classified into Types 20A and 20B depending on the location of the kitchen and dining area (Figure 3). As shown in

Table 6. Area of major spaces in public rental housing (1990s).

Type		L and R	R	L	K and D	Others	Balcony
≥20 m2 < 30 m2	20A	9.9 (37.5)	5.7 (21.5)	-	6.6 (25.2)	4.2 (15.9)	5.4
	20B	9.9 (37.6)	5.0 (19.2)	-	7.6 (28.7)	3.6 (13.8)	5.2
≥30 m2 < 40 m2	30A	13.2 (38.1)	6.3 (18.1)	-	8.7 (25.0)	6.5 (18.6)	6.1
	30B	11.5 (32.2)	6.8 (18.9)	-	10.6 (29.7)	6.9 (19.1)	7.0
	30C	8.5 (21.9)	10.4 (26.7)	-	13.1 (33.5)	7.0 (18.0)	8.8
≥40 m2 < 50 m2	40A	16.3 (38.3)	6.6 (15.5)	-	11.0 (22.0)	9.1 (20.4)	6.8
	40B	9.7 (22.7)	13.0 (30.3)	-	13.0 (30.3)	7.2 (16.8)	9.5
	40C	-	17.1 (39.8)	11.1 (25.8)	9.3 (21.7)	5.4 (12.6)	12.1
	40D	-	18.0 (36.2)	7.2 (14.4)	14.7 (29.7)	9.8 (19.7)	8.6

, the combined bedroom–living room occupies the largest share, with an average area of 9.91 m² (37.56%), followed by the kitchen and dining area at 7.39 m² (approximately 28%). This configuration reflects a planning strategy aimed at maximizing spatial efficiency by integrating primary living functions within a limited floor area. In addition, as indicated in

Table 7. Plan configuration of public rental housing (1990s).

Type		Frontage Width	Depth	Width-to-Depth Ratio	Number of Bays
≥20 m2 < 30 m2	20A	3.60	9.30	2.58	1
	20B	3.38	8.94	2.64	1
≥30 m2 < 40 m2	30A	4.20	10.10	2.40	1
	30B	5.40	9.90	1.83	2
	30C	5.80	10.80	1.86	2
≥40 m2 < 50 m2	40A	4.50	11.20	2.49	1
	40B	6.30	8.30	1.32	2
	40C	6.00	9.10	1.52	2
	40D	5.70	9.70	1.70	2

, the average width-to-depth ratio is 2.61, revealing a slender one-bay layout characterized by a relatively deep plan compared to its frontage.

The spatial composition of the 30 m² units is generally similar to that of the 20 m² units; however, the typologies are further differentiated by bay structure and balcony configuration (Figure 3). The dominant Type 30A adopts a one-bay structure, maintaining a layout similar to that of the 20 m² units. In contrast, Types 30B and 30C, which are typically located in end units of corridor-type apartment buildings, adopt a two-bay structure, indicating a shift in spatial organization. In these types, the kitchen and dining area is planned as an independent space rather than shared circulation space, and either the bedroom or living room is positioned along the façade, resulting in an increased balcony area. As shown in Table 6, the average balcony areas of Types 30B and 30C are 7.0 m² and 8.8 m², respectively, which are larger than the 6.1 m² average of Type 30A. Furthermore, as presented in Table 7, the width-to-depth ratio decreases from 2.40 in Type 30A to 1.83 and 1.86 in Types 30B and 30C, respectively, indicating a shift toward a more compact and balanced plan configuration. This can be interpreted as an early attempt to enhance spatial differentiation and functional zoning within the same floor area.

More pronounced changes are observed in the 40 m² units. While Types 40A and 40B retain the combined bedroom–living room configuration, Types 40C and 40D introduce a separation between the living room and bedrooms, resulting in a more functionally differentiated layout (Figure 3). In particular, in the two-bay structures of Types 40C and 40D, the living room and bedrooms are positioned along the front façade, and the kitchen and dining area is organized as an independent space separated from the circulation zone. As shown in Table 6, the living room areas in Types 40C and 40D are 11.1 m² (25.8%) and 7.2 m² (14.4%), respectively, demonstrating a clear functional separation compared to earlier layouts. Changes are also observed in the configuration of balconies. According to Table 6, the average balcony area of the one-bay Type 40A is 6.8 m², whereas that of the two-bay Types 40B–40D increases to an average of 9.7 m². This indicates an expansion of semi-outdoor space associated with changes in the floor plan configuration. In addition, as shown in Table 7, the width-to-depth ratio decreases from an average of 2.49 in the one-bay Type 40A to 1.51 in the two-bay types, suggesting a transition toward more proportionally balanced layouts.

Overall, the floor plans of public rental housing in the 1990s are characterized by small-sized units, simple spatial organization, and slender one-bay configurations. At the same time, certain types exhibit the emergence of two-bay structures and spatial separation, indicating the initial stage of transformation toward more differentiated and complex spatial arrangements. These characteristics are clearly illustrated in Figure 4, where the dominance of the one-bay layout and the elongated unit proportion can be observed, with the combined living and sleeping space occupying the largest portion of the unit.

4.1.2. Characteristics of Public Rental Housing Floor Plans in the 2000s

As shown in

Table 8. Overview of public rental housing floor plan types in the 2000s.

Category	Type	Unit Floor Area (m2)	Number of Households	Ratio (%)	Number of Complexes	Remarks
≥20 m2 < 30 m2	20A	26	296	2.20	2
	Subtotal		296	2.20
≥30 m2 < 40 m2	30A-1	36, 39	1646	12.24	7
	30A-2	36, 39	1504	11.18	6	End unit
	30A-3	39	353	2.62	3	End unit
	30B-1	36	495	3.68	3
	30B-2	36	86	0.64	1	End unit
	30C	39	136	1.01
	Subtotal		4220
≥40 m2 < 50 m2	40A-1	45, 46, 47	2698	20.06	11
	40A-2	45, 46, 47	990	7.36	6	End unit
	40A-3	45, 46, 47	1083	8.05	6	End unit
	40A-4	46	368	2.74	2	End unit
	40B	45	27	0.20	1
	Subtotal		5166
≥50 m2 < 60 m2	50A-1	51	2029	15.09	10
	50A-2	51	574	4.27	6	End unit
	50A-3	51, 59	490	3.64	3	Staircase type
	50B	59	475	3.53	4	Staircase type
	50C	59	110	0.82	1	Staircase type
	50D	59	88	0.65	2	Staircase type
	Subtotal		3766
	Total		13,448	100.0

, public rental housing in the 2000s was developed with unit sizes ranging from 26 m² to 59 m², indicating an expansion in housing size compared to the 1990s. The floor plan typologies were further diversified according to unit size, comprising one type in the 20 m² range, three types in the 30 m² range, two types in the 40 m² range, and four types in the 50 m² range. This reflects the increasing diversification of floor plan types in response to broader residential demands.

The 20 m² units are characterized by a studio-type layout, in which the bedroom, living room, and kitchen–dining area are integrated into a single space (Figure 5). As shown in

Table 9. Area of major spaces in public rental housing (2000s).

Type		L and R	R	L	K and D	Others	Balcony
≥20 m2 < 30 m2	20A	20.17 (75.5)	-	-	-	6.5 (24.4)	6.51
≥30 m2 < 40 m2	30A-1	14.8 (38.4)	8.0 (20.6)	-	11.2 (28.9)	4.7 (12.3)	6.9
	30A-2	14.8 (38.0)	6.7 (17.3)	-	11.9 (30.4)	5.6 (14.4)	7.6
	30A-3	15.0 (38.0)	8.4 (21.1)	-	11.5 (29.0)	4.7 (11.8)	9.4
	30B-1	12.2 (33.2)	9.1 (24.8)	-	9.7 (26.4)	5.8 (15.7)	7.9
	30B-2	10.0 (27.1)	8.5 (23.0)	-	13.3 (35.9)	5.2 (14.0)	7.5
	30C		18.7 (23.0)	10.4 (25.3)	15.4 (38.9)	5.5 (13.8)	9.3
≥40 m2 < 50 m2	40A-1	-	17.3 (37.2)	9.8 (21.0)	14.0 (30.0)	5.5 (11.8)	9.5
	40A-2	-	17.2 (37.2)	9.8 (21.1)	13.6 (29.4)	5.5 (11.8)	14.1
	40A-3	-	17.3 (27.2)	9.8 (21.1)	14.2 (30.6)	5.2 (11.2)	12.7
	40A-4	-	17.4 (37.2)	11.7 (24.9)	13.0 (27.7)	4.8 (10.2)	17.6
	40B	-	17.2 (37.5)	9.9 (21.6)	13.1 (28.6)	5.6 (12.2)	13.0
≥50 m2 < 60 m2	50A-1	-	19.5 (37.5)	14.4 (27.8)	12.5 (24.2)	5.5 (10.5)	10.5
	50A-2	-	19.3 (37.1)	14.7 (28.3)	12.5 (24.0)	5.5 (10.6)	14.8
	50A-3	-	20.9 (36.7)	17.0 (29.5)	10.3 (18.1)	8.7 (15.7)	20.5
	50B	-	26.5 (44.4)	17.1 (28.6)	8.7 (14.5)	7.5 (12.6)	23.0
	50C	-	27.2 (45.4)	18.6 (31.0)	8.4 (14.0)	5.8 (9.6)	23.4
	50D	-	24.6 (41.3)	18.4 (30.8)	8.4 (14.0)	8.2 (13.8)	24.8

, this unified space occupies approximately 20.2 m² (76.6%) of the total unit area, indicating that spatial efficiency remains a key planning strategy in small-sized units. In addition, as indicated in

Table 10. Plan configuration of public rental housing (2000s).

Type		Frontage Width	Depth	Width-to-Depth Ratio	Number of Bays
≥20 m2 < 30 m2	20A	4.3	8.9	2.07	1
≥30 m2 < 40 m2	30A-1	4.7	11.0	2.34	1
	30A-2	4.6	11.7	2.54	1
	30A-3	4.8	11.7	2.44	1
	30B-1	6.5	8.5	1.31	2
	30B-2	6.3	8.9	1.42	2
	30C	6.5	9.6	1.48	2
≥40 m2 < 50 m2	40A-1	6.5	9.8	1.51	2
	40A-2	6.5	10.7	1.65	2
	40A-3	6.5	10.1	1.55	2
	40A-4	6.6	12.0	1.82	2
	40B	6.7	9.6	1.43	2
≥50 m2 < 60 m2	50A-1	6.9	9.9	1.44	2
	50A-2	6.9	10.7	1.55	2
	50A-3	7.5	11.5	1.53	2
	50B	7.8	11.6	1.49	2
	50C	10.3	10.8	1.05	3
	50D	8.1	10.9	1.35	3

, the average width-to-depth ratio is 2.07, maintaining a slender one-bay configuration similar to that of the 1990s.

In the 30 m² range, the overall spatial composition is similar to that of the 1990s; however, greater variation is observed in bay structure and balcony configuration (Figure 5). The most prevalent type, 30A-1, adopts a one-bay structure, while Types 30A-2 and 30A-3 represent modified versions with changes in entrance location or balcony configuration. These variations are typically found in end units that utilize dead-end corridor spaces. In contrast, Types 30B and 30C adopt a two-bay structure, indicating a shift in spatial organization. In these types, bedrooms are positioned along the façade, balcony areas are expanded, and the kitchen–dining area is planned as an independent space rather than a shared circulation space. As shown in Table 9, the kitchen–dining area in Types 30B and 30C averages approximately 12 m², which is slightly larger than the 11.6 m² average in Type 30A. Similarly, balcony areas increase from an average of 7.6 m² in Type 30A to 7.8 m² and 9.3 m² in Types 30B and 30C, respectively. As indicated in Table 10, the width-to-depth ratio decreases from an average of 2.44 in Type 30A to 1.37 and 1.48 in Types 30B and 30C, suggesting a transition toward more compact and balanced plan configurations. This reflects the gradual strengthening of spatial differentiation and functional zoning.

In the 40 m² range, the two-bay structure becomes predominant, marking a clear departure from the one-bay dominance of the previous period (Figure 5). All unit types generally consist of a living room, two bedrooms, a kitchen–dining area, a bathroom, and a balcony, with a front–rear zoning structure in which the living room and main bedroom are located at the front, and the kitchen–dining area and secondary bedroom are positioned at the rear. The most common type, 40A-1, follows this basic configuration, while Types 40A-2, 40A-3, and 40A-4 represent variations that incorporate additional balconies or modified entrance locations, taking advantage of the spatial conditions of end units. As shown in Table 9, the living room area in Type 40A-1 is approximately 9.8 m² (21.0%), and the kitchen–dining area is about 14.0 m² (30.0%), indicating relatively stable spatial proportions. In contrast, Type 40B features a modified kitchen–dining layout and an expanded balcony area of approximately 13 m², suggesting an increase in semi-outdoor space. As indicated in Table 10, the width-to-depth ratio ranges from 1.43 to 1.82, reflecting a shift toward more balanced plan proportions compared to the 1990s.

In the 50 m² range, floor plan typologies become increasingly diverse, primarily according to the number of bedrooms and bay configuration (Figure 5). The most common type, 50A-1, maintains a layout similar to that of the 40 m² units, consisting of a living room, two bedrooms, a kitchen–dining area, a bathroom, and a balcony. Variants such as 50A-2 and 50A-3 retain the same spatial structure while introducing modifications in balcony configuration or entrance location. In contrast, Types 50B, 50C, and 50D, all with a floor area of 59 m², include three bedrooms, reflecting the increased spatial complexity associated with larger unit sizes. Type 50B adopts a two-bay configuration, with a rear bedroom accessed through the kitchen–dining area, whereas Types 50C and 50D adopt a three-bay structure, with two bedrooms and the living room positioned along the front façade. This indicates a more articulated spatial organization and an expanded façade composition. As shown in Table 9, the living room area ranges from 14.4 m² (27.8%) to 18.6 m² (31.0%), with an average of 17.7 m² (29.6%) in the 59 m² units, indicating an increase in living space as unit size expands. In contrast, the kitchen–dining area in these types averages approximately 8.5 m², which is smaller than the 12.2 m² average in the 50A types, suggesting a redistribution of space to accommodate additional bedrooms. Balcony areas range widely from 10.5 m² to 24.8 m², with most types exceeding 20 m², reflecting a significant expansion of external space. This is particularly associated with staircase-type buildings, where the absence of internal corridors allows for greater balcony extension. As indicated in Table 10, the width-to-depth ratio ranges from 1.05 to 1.55, with an average of approximately 1.4, indicating a transition toward more compact and proportionally balanced layouts. Notably, Type 50C, with a ratio of 1.05, approaches a nearly square plan configuration enabled by the three-bay structure.

Overall, public rental housing floor plans in the 2000s are characterized by increased unit sizes, diversification of typologies, the widespread adoption of two-bay configurations, and the emergence of three-bay layouts in larger units. Compared to the 1990s, these changes reflect a clear trend toward enhanced spatial differentiation, functional zoning, and more balanced plan proportions. These characteristics are clearly illustrated in Figure 6, where the transition to two-bay configurations can be observed, along with clearer spatial separation between the living room, bedrooms, and kitchen–dining area, reflecting enhanced functional zoning.

4.1.3. Characteristics of Public Rental Housing Floor Plans in the 2010s

As shown in

Table 11. Overview of public rental housing floor plan types in the 2010s.

Category	Type	Unit Floor Area (m2)	Number of Households	Ratio (%)	Number of Complexes	Remarks
≥20 m2 < 30 m2	20A-1	21, 24, 26	1004	7.29	4	One-room layouts
	20A-2	26	302	2.19	4	One-room layouts
	20B-1	26	216	1.57	2
	20B-2	29	90	0.65	1
	Subtotal		1621
≥30 m2 < 40 m2	30A-1	37, 39	2293	15.09	6
	30A-2	36	2118	16.66	9
	30A-3	36	94	0.68	1	End unit
	30A-4	39	303	2.20	3	End unit
	30B	37	331	2.40	2
	Subtotal		5139
≥40 m2 < 50 m2	40A-1	46	1558	11.31	7
	40A-2	46	1568	11.38	10
	40A-3	46	532	3.86	5	Staircase type
	40A-4	46	412	2.99	3	End unit, tower
	40A-5	46	266	1.93	4	End unit, tower
	40B	46	68	0.49	1
	40C	46	72	0.52	1
	Subtotal		4476
≥50 m2 < 60 m2	50A-1	51	388	2.82	2
	50A-2	51	446	3.24	5
	50A-3	51	608	4.41	4
	50A-4	51	102	0.74	2
	50A-5	51	84	0.61	3
	50B-1	51	148	1.07	1
	50B-2	51	114	0.83	1
	50B-3	51	208	1.51	2
	50C	51	48	0.35	1
	50D	51	60	0.44	1
	50E	59	278	2.02	2
	50F	59	64	0.46	1
	Subtotal		2548
	Total		13,775

, public rental housing in the 2010s was developed with unit sizes ranging from 21 m² to 59 m², exhibiting a mixed structure of small- and medium-sized units compared to earlier periods. The floor plan typologies were further subdivided by size, comprising two types in the 20 m² range, two types in the 30 m² range, three types in the 40 m² range, and six types in the 50 m² range. This reflects an increasing complexity of floor plan configurations in response to diverse household types and lifestyles.

In the 20 m² range, studio-type layouts remain the dominant form; however, the unit size varies from 21 m² to 29 m², indicating greater diversity in spatial composition. Type 20A represents a typical studio layout in which the bedroom, living room, and kitchen–dining area are integrated into a single space, whereas Type 20B separates the combined bedroom–living room from an additional bedroom (Figure 7). As shown in

Table 12. Area of major spaces in public rental housing (2010s).

Type		L and R	R	L	K and D	Others	Balcony
≥20 m2 < 30 m2	20A-1	20.1 (80.5)	-	-	-	4.9 (19.5)	6.1
	20A-2	21.1 (78.6)	-	-	-	5.6 (21.0)	6.0
	20B-1	-	10.7 (39.7)	-	6.7 (25.1)	4.6 (17.0)	6.2
	20B-2	-	11.9 (39.7)	-	9.3 (31.1)	4.5 (15.1)	6.7
≥30 m2 < 40 m2	30A-1	15.1 (38.7)	7.6 (19.4)	-	11.6 (29.8)	4.7 (12.1)	8.3
	30A-2	13.1 (35.7)	6.1 (16.5)	-	11.4 (31.1)	6.1 (16.6)	7.5
	30A-3	12.9 (35.2)	6.1 (16.6)	-	11.6 (31.5)	6.2 (16.7)	10.7
	30A-4	15.4 (38.6)	8.2 (20.6)	-	11.4 (28.6)	4.8 (12.2)	12.3
	30B	-	12.0 (31.9)	9.2 (24.4)	8.7 (23.1)	7.7 (20.5)	9.7
≥40 m2 < 50 m2	40A-1	-	17.2 (36.8)	9.9 (21.3)	14.2 (30.4)	5.4 (11.6)	10.3
	40A-2	-	17.1 (36.7)	8.0 (17.2)	16.1 (34.6)	6.1 (13.0)	9.7
	40A-3	-	17.4 (37.3)	8.7 (18.6)	15.4 (33.0)	5.5 (11.7)	15.7
	40A-4	-	17.7 (37.8)	9.8 (21.0)	14.2 (30.4)	5.2 (11.1)	15.4
	40A-5		17.1 (36.9)	7.8 (16.7)	15.9 (34.1)	5.7 (12.3)	14.6
	40B	-	19.4 (41.4)	9.8 (20.9)	14.2 (30.3)	5.7 (12.1)	19.1
	40C	-	18.2 (38.9)	9.6 (20.5)	12.8 (27.3)	5.9 (12.6)	14.1
≥50 m2 < 60 m2	50A-1	-	19.9 (38.3)	12.0 (23.1)	15.2 (29.3)	5.3 (10.1)	12.8
	50A-2	-	18.9 (36.6)	11.0 (21.2)	15.5 (30.0)	6.3 (12.2)	10.2
	50A-3	-	19.0 (36.8)	10.4 (20.3)	16.3 (31.6)	5.9 (11.5)	16.2
	50A-4	-	19.8 (38.3)	10.9 (21.0)	15.3 (29.6)	5.8 (11.1)	10.0
	50A-5	-	19.0 (36.7)	9.9 (19.1)	17.0 (32.8)	5.9 (11.3)	15.1
	50B-1	-	20.2 (38.9)	16.7 (32.1)	10.1 (19.5)	5.0 (9.6)	24.0
	50B-2	-	17.5 (34.1)	19.9 (38.8)	8.2 (16.0)	5.7 (11.2)	17.7
	50B-3	-	18.7 (35.9)	18.3 (35.3)	9.1 (17.5)	5.6 (10.7)	19.2
	50C	-	18.1 (34.9)	17.8 (34.3)	9.4 (18.2)	6.5 (12.5)	23.4
	50D	-	22.2 (43.0)	11.7 (22.6)	10.7 (20.8)	7.1 (13.7)	20.5
	50E	-	27.4 (46.1)	19.0 (32.0)	7.6 (12.8)	5.3 (9.0)	24.7
	50F	-	27.0 (45.4)	13.6 (22.9)	12.7 (21.4)	6.2 (10.4)	12.0

, the unified space in Type 20A occupies an average of 20.5 m² (approximately 80%), while in Type 20B, the combined bedroom–living room accounts for approximately 10.7–11.9 m² (about 39.7%), and the kitchen–dining area occupies 6.7–9.3 m² (25.1–31.1%). In addition, as indicated in

Table 13. Plan configuration of public rental housing (2010s).

Type		Frontage Width	Depth	Width-to-Depth Ratio	Number of Bays
≥20 m2 < 30 m2	20A-1	4.04	8.73	2.16	1
	20A-2	4.05	9.41	2.32	1
	20B-1	4.20	9.10	2.17	1
	20B-2	4.50	9.11	2.20	1
≥30 m2 < 40 m2	30A-1	4.92	10.58	2.15	1
	30A-2	2.78	10.34	2.16	1
	30A-3	4.31	11.87	2.75	1
	30A-4	5.00	11.76	2.35	1
	30B	6.44	8.44	1.31	2
≥40 m2 < 50 m2	40A-1	6.41	9.84	1.54	2
	40A-2	6.55	10.10	1.54	2
	40A-3	6.50	10.18	1.57	2
	40A-4	6.40	11/32	1.77	2
	40A-5	6.50	11.48	1.77	2
	40B	6.40	11.61	1.81	2
	40C	6.55	10.01	1.53	2
≥50 m2 < 60 m2	50A-1	6.90	10.17	1.47	2
	50A-2	6.87	11.67	1.70	2
	50A-3	6.93	10.41	1.50	2
	50A-4	6.91	10.55	1.53	2
	50A-5	6.91	11.99	1.74	2
	50B-1	7.00	11.81	1.69	2
	50B-2	7.00	11.73	1.68	2
	50B-3	6.94	11.83	1.70	2
	50C	9.90	10.33	1.04	3
	50D	8.70	10.56	1.21	3
	50E	8.30	11.74	1.41	2
	50F	8.00	9.54	1.19	2

, the average width-to-depth ratio is approximately 2.2 for both types, confirming that the slender one-bay configuration is still maintained.

In the 30 m² range, floor plans can be broadly classified into two types according to the bay structure, with Type 30A further subdivided based on balcony configuration (Figure 7). Type 30A consists of a combined bedroom–living room, a secondary bedroom, a kitchen–dining area, a bathroom, and a balcony, with Type 30A-1 representing the most typical one-bay configuration. Types 30A-2, 30A-3, and 30A-4 are variations involving additional or modified balcony configurations, often achieved by utilizing dead-end corridor spaces in end units. In contrast, Type 30B adopts a two-bay structure, in which the bedroom and living room are separated, and the bedroom is positioned along the façade, resulting in an expanded balcony. In addition, a laundry space is introduced near the entrance, and the kitchen–dining area is designed as an independent space, indicating a further strengthening of spatial differentiation. As shown in Table 12, the combined bedroom–living room area in Type 30A ranges from 12.9 m² to 15.4 m² (35.2–38.6%), while the kitchen–dining area ranges from 11.4 m² to 11.6 m² (28.6–31.5%). In contrast, in Type 30B, the living room occupies approximately 9.2 m² (24.4%), and the two bedrooms together account for about 12.9 m² (31.9%), indicating a reduction in individual room size but an increase in spatial separation and independence. Balcony areas also increase from an average of 8.3 m² in Type 30A-1 to 10.7 m² and 12.3 m² in Types 30A-3 and 30A-4, respectively. As indicated in Table 13, the width-to-depth ratio decreases from 2.15–2.35 in Type 30A to 1.31 in Type 30B, suggesting a transition toward more compact and square-like layouts.

In the 40 m² range, all floor plans adopt a two-bay structure and consist of a living room, two bedrooms, a kitchen–dining area, a bathroom, and a balcony (Figure 7). A front–rear zoning structure is consistently maintained, with the living room and main bedroom located at the front and the kitchen–dining area and secondary bedroom positioned at the rear. The 40A series maintains a basic layout while introducing variations through additional or modified balcony configurations. Type 40B, located in tower-type residential blocks, features balconies on both the front and rear sides due to differences in entrance placement compared to corridor-type buildings. Type 40C modifies the kitchen–dining layout based on its location as an end unit and places the balcony on the front side. As shown in Table 12, the average living room area in the 40A type is approximately 8.5 m² (18.3%), while Types 40B and 40C have slightly larger areas of 9.8 m² (20.9%) and 9.6 m² (20.5%), respectively. The kitchen–dining area in Type 40A averages 15.3 m² (32.9%), whereas Types 40B and 40C measure 14.2 m² (30.3%) and 12.8 m² (27.3%), respectively. Balcony areas are also larger in Types 40B and 40C (19.1 m² and 14.1 m²) compared to Type 40A (11.9 m²), indicating an expansion of external space. As indicated in Table 13, the width-to-depth ratio ranges from 1.54 to 1.81, suggesting a shift toward more balanced plan proportions compared to earlier periods.

In the 50 m² range, floor plan diversity becomes most pronounced, with typologies classified according to the number of bedrooms and bay structure (Figure 7). Types 50A and 50B adopt a two-bay structure and consist of a living room, two bedrooms, a kitchen–dining area, a bathroom, and a balcony, while Type 50C adopts a three-bay configuration, placing both bedrooms along the façade. Types 50D, 50E, and 50F include three bedrooms and are designed with either two-bay or three-bay configurations. Notably, Type 50F integrates the living room and kitchen–dining area into a single space, representing a departure from conventional layouts. As shown in Table 12, in 51 m² units (Types 50A–50D), the living room area varies significantly from 9.9 m² (19.1%) to 19.9 m² (38.8%), while the kitchen–dining area ranges from 8.2 m² (16.0%) to 17.0 m² (32.8%). This indicates that spatial allocation varies considerably depending on the layout type, even within the same unit size. Balcony areas also show wide variation, ranging from 10.2 m² to 24.7 m², reflecting increased diversity in the use of external space. As indicated in Table 13, the width-to-depth ratio ranges from 1.04 to 1.74, with an average of approximately 1.49, indicating an overall trend toward more square-like plan proportions. In particular, Type 50C, with a ratio of 1.04, exhibits a nearly square configuration enabled by the three-bay structure.

Overall, public rental housing floor plans in the 2010s are characterized by diversification of typologies, increased complexity in spatial composition, and the widespread adoption of two-bay and three-bay configurations. Compared to earlier periods, these changes reflect a further strengthening of spatial differentiation and a closer alignment with diverse living patterns. These characteristics are clearly illustrated in Figure 8, where the diversification of layouts is evident, including the emergence of three-bay configurations and more complex spatial arrangements reflecting diverse household needs.

4.2. Comparison of Floor Plan Change Characteristics by Size of Public Rental Housing

In the 1990s, when permanent rental housing began to be constructed in Korea, public rental housing units ranged from a minimum of 26 m² to a maximum of 49 m². However, after the National Rental Housing Supply Policy was introduced in 1998, the maximum unit size increased, and public rental housing constructed in the 2000s reached up to 59 m².

Examining the unit sizes by period, the 20 m² range consisted only of 26 m² units until the 2000s. However, after 2010, various unit sizes were introduced within this range, including 21 m², 24 m², 26 m², and 29 m². In the 30 m² range, units smaller than 35 m² accounted for approximately 60% of the total in the 1990s. After 2000, however, only units of 36 m² or larger were planned. The 40 m² range shows a different pattern across periods. In the 1990s, units were mainly planned at approximately 41 m² and 49 m², while in the 2000s, several sizes ranging from 45 to 47 m² were supplied. In contrast, in the 2010s, only units of approximately 46 m² were planned. The 50 m² range, which began to be supplied in the 2000s, consisted mainly of two sizes, 51 m² and 59 m², both in the 2000s and the 2010s. Therefore, the overall unit size within this range did not change significantly over time.

These results indicate that since the 2010s, the smallest housing units in the 20 m² range have become more diversified in size, whereas units larger than 40 m² have tended to concentrate on a limited number of standardized sizes rather than diversifying in area. Based on the analysis of floor plan changes by period and unit size, several characteristics were identified. Regarding the classification of floor plan types by construction period, the 1990s floor plans were categorized mainly according to bay structure or the location of the kitchen–dining space. After 2000, however, the floor plan types were first classified by bay structure and then further subdivided according to balcony configuration.

The floor plan structure of the 20 m² range remained a one-bay configuration across all periods, but changes occurred in the spatial composition of the units. In the 2000s, however, the previous configuration of a small bedroom and kitchen–dining space was replaced by a one-room layout in which these spaces were integrated into a single space. This type of layout also continued in 2010, although additional variations were introduced through changes in balcony configuration. In addition, in the 2010s, a new floor plan type was introduced that modified the balcony configuration of the 20A type from the 1990s. Although all units in the 20 m² range maintained a one-bay structure, the frontage width increased after 2000 compared with the 1990s. In particular, in the one-room layouts of the 2000s, the width-to-depth ratio decreased to approximately 2.07, indicating that the frontage facing the exterior became wider. These characteristics can be observed in Figure 9.

Floor plans in the 30 m² range were designed with either one-bay or two-bay structures, although the proportion of each type varied by period. In the 1990s, when the supply of housing units in the 30 m² range was the highest, the 30A type was the only one-bay floor plan and accounted for about 90% of the floor plan types in this size range. In the 2000s and 2010s, one-bay structures continued to account for the majority of public rental housing units in the 30 m² range, representing approximately 83% and 93.6% of the supply, respectively. Within the one-bay structure, the arrangement and composition of spaces remained largely unchanged across periods. However, in the 2000s and 2010s, the 30A type from the 1990s was further subdivided into three to four variations through changes in balcony configuration. In the 1990s, the 30C type with a two-bay structure arranged the combined living and sleeping space and the bedroom on the front side of the unit, while the kitchen–dining space was planned as a space with clear territoriality. This spatial configuration continued to appear in later periods. In contrast, in the two-bay structures of the 2000s and 2010s, the bedroom and living room were clearly separated, and an additional bedroom was arranged on the front side of the unit. As a result, a new floor plan type emerged that included a main bedroom along with a kitchen–dining space. In terms of floor plan proportions, the one-bay structure showed little variation over time. However, the width-to-depth ratio of the two-bay structure decreased from 1.85 in the 1990s to 1.40 in the 2000s and 1.31 in the 2010s. This indicates that the frontage width of the living room and bedroom facing the south gradually increased. These characteristics can be observed in Figure 10.

In the 40 m² range, both one-bay and two-bay structures were planned in the 1990s, whereas only two-bay structures were developed after the 2000s. In the 1990s, the floor plans commonly included a combined living and sleeping space, whereas after the 2000s, the bedroom and living room were separated and planned as independent spaces. In particular, in the 1990s, the 40A type, which arranged the bedroom and living space in a one-bay structure, accounted for approximately 58% of the total supply and represented the most typical floor plan type in this size range. After the 2000s, however, all floor plans adopted a two-bay structure consisting of an independent living room and two bedrooms. In addition, in both the 2000s and 2010s, the 40A-1 type was further subdivided into four to five variations depending on changes in balcony configuration or the addition of balconies. The results show that both the number and the area of balconies increased over time. The width-to-depth ratio of the two-bay structure was 1.51 in the 1990s, 1.59 in the 2000s, and 1.64 in the 2010s, which is higher than that of the two-bay floor plans in the 30 m² range. These characteristics can be observed in Figure 11.

The 50 m² floor plans, which began to be supplied in the 2000s, were designed with both two-bay and three-bay structures. However, in both periods, the two-bay structure accounted for more than 95% of the total supply. In terms of spatial composition, both the two-bay and three-bay structures consisted of independent living rooms and bedrooms. In both the 2000s and the 2010s, the arrangement of major spaces according to the bay structure showed similar characteristics. In each period, the 50A-1 type represents the most basic floor plan and is subdivided according to balcony configuration and entrance location. In particular, in the 50 m² range, various floor plan types emerged in addition to the subdivision of types through changes in balcony configuration. In corridor-type residential buildings, the entrance was generally located along the rear corridor. However, in staircase-type residential buildings, the entrance position changed, which appears to have contributed to greater diversification of floor plan types. For example, in the 50C type of the 2000s, the kitchen was placed between the bedrooms, and a balcony was connected to the side. In addition, in the 50F type of the 2010s, the living room and kitchen–dining space were planned as a single integrated space. This configuration is notable considering that the unit size is 59 m², which is the largest among public rental housing units. The width-to-depth ratio of the two-bay structure increased slightly from 1.51 in the 2000s to 1.56 in the 2010s. In contrast, the three-bay structure showed a decrease from 1.20 in the 2000s to 1.13 in the 2010s, indicating different trends over time. In particular, the 50E type in the 2010s shows a ratio of 1.04, indicating a floor plan shape close to a square. This trend reflects a planning intention to strengthen the south-facing arrangement of major spaces. It also suggests that sunlight and views have become increasingly important considerations in the floor plan design of public rental housing. These characteristics can be observed in Figure 12.

4.3. Review of Legal and Institutional Frameworks Related to Floor Plans

The legal and institutional frameworks related to the floor plans of public rental housing in Korea include the Building Act, the Housing Act, the district unit plan implementation guidelines, and the housing construction standards of the Korea Land and Housing Corporation (LH). This section examines the major regulations that have influenced the planning of public rental housing floor plans.

The Regulations on Housing Construction Standards, enacted in 1991, provide detailed provisions related to housing construction under the Housing Act. At the time of enactment, Article 3 (Dimensions and Standard Sizes) required that, for housing units with an area of 50 m² or less, the living room and bedrooms should have minimum dimensions of at least 2.4 m on each side. However, these dimensional requirements were removed in the 1997 revision and have not been applied since then. Article 10 of the same regulation also required the length of an apartment building to be less than 120 m, but this provision was deleted in 1996. These two regulations, which are now abolished, were found to have been widely applied in the planning of public rental housing during the 1990s.

Within the Building Act, provisions directly related to floor plans include regulations concerning balconies and windows. According to the relevant laws, balconies are additional spaces installed outside the external wall of a building and are not included in the exclusive floor area. Due to Korea’s climate conditions, it was common for residents to illegally enclose balconies by installing windows and removing the external wall doors in order to expand interior space. As a result, balcony expansion was legalized through a revision of the Enforcement Decree of the Building Act in December 2005. After this revision, apartment floor plans began to incorporate balcony expansion into the design, which allowed greater flexibility in the arrangement of kitchens, dining spaces, and bedrooms. According to Article 52 of the Enforcement Decree of the Building Act, windows must be installed with an area of at least one-tenth of the floor area for daylighting and one-twentieth for ventilation in living rooms. These regulations appear to have constrained floor plan design by fixing the living room as a primary space facing the south and the balcony.

Although the specific provisions vary across development districts, the district unit plan implementation guidelines commonly include regulations related to the length of residential buildings and the arrangement of building heights. Before the 1990s, most apartment buildings in Korea were planned in linear flat forms [9]. In order to avoid monotonous urban landscapes resulting from long flat-type buildings, district unit plans imposed restrictions on the maximum length of apartment buildings. However, these regulations were applied differently to rental apartments and privately sold apartments. For example, in the Byeolnae District of Namyangju analyzed in this study, the maximum building length was limited to less than 100 m for buildings up to 10 floors and less than 80 m for buildings between 11 and 15 floors. This limit was approximately 20 m longer than the standard applied to privately sold apartments. In most district unit plans from the 1990s to the 2010s, the building length limit for residential buildings between 11 and 15 floors was generally set at less than 80 m. A review of district unit plan implementation guidelines confirmed that all case study sites were planned within the 80 m limit, except for the Hwaseong Dongtan 1 District, where the building length was restricted to less than 70 m for buildings between 11 and 15 floors. Because public rental housing units are typically small and often adopt one-bay structures, most buildings were planned as corridor-type slab buildings. Consequently, slab-type residential buildings with repetitive unit layouts have been the dominant building form for public rental housing over the past 30 years, resulting in relatively similar floor plan patterns. However, in the 2010s, district unit plans introduced designated high-rise zones, where building forms were required to respond to the permitted building height. In these zones, tower-type residential buildings began to appear, and this change in building form contributed to greater diversity in floor plan types. Furthermore, tower-type buildings allowed variations in balcony configurations depending on the location of the housing unit within the building, which also contributed to the diversification of floor plans. These characteristics can be observed in Figure 13.

Finally, the architectural design guidelines, unit design guidelines, and development design competition guidelines of the Korea Land and Housing Corporation (LH), which has been responsible for constructing most public rental housing in Korea, provide detailed standards for unit design. These guidelines specify minimum dimensions for various spatial elements, ranging from storage furniture such as shoe cabinets to the minimum size of each room. For example, according to the Unit Design Guidelines (Draft), the minimum width of the main bedroom must be at least 3 m, and the minimum balcony expansion width must be at least 2.4 m. In the case of development design competition guidelines, the minimum width of the living room is required to be at least 3.6 m, while that of the main bedroom must be at least 3.3 m. In addition, the design standards present recommended bathroom dimensions according to housing size, and kitchen layouts such as linear or L-shaped configurations are specified depending on the housing area. The minimum effective width of a balcony is generally required to be at least 1 m. However, the spaces eligible for balcony expansion differ according to housing size. For example, in 51 m² units, balcony expansion is typically allowed only for the living room, whereas in 59 m² units, both the living room and secondary bedroom may be expanded.

Overall, the floor plans of public rental housing in Korea appear to have been shaped through a staged process according to these legal and institutional frameworks. Among these regulations, the arrangement of living rooms in relation to daylighting has been the most fundamental requirement influencing floor plan design across all periods. The minimum dimensional requirements and building length restrictions under the Housing Act in the 1990s functioned as limiting factors in floor plan composition. In contrast, the legalization of balcony expansion in 2005 provided an important opportunity for diversification in floor plan design. Although the building length restrictions in district unit plans remained largely unchanged over the past 30 years, the introduction of high-rise zones after the 2000s encouraged changes in building form. This change, combined with the expansion of balconies, contributed to the diversification of floor plans. Furthermore, the architectural design guidelines of the Korea Land and Housing Corporation established detailed standards for minimum room sizes and balcony expansion ranges according to housing size. These guidelines functioned as more practical regulatory tools influencing floor plan design than general legal regulations. Therefore, the floor plans of public rental housing in Korea have been shaped primarily by institutional standards and guidelines established by public authorities rather than by autonomous design changes driven by market demand.

5. Discussion

This study addresses three research questions: (1) how floor plan types of public rental housing have evolved over time; (2) what key characteristics can be identified according to housing size; and (3) how legal and institutional frameworks have influenced these changes. Accordingly, this section discusses the findings in relation to these research questions.

5.1. Temporal Evolution of Floor Plan Types

The floor plans of public rental housing in Korean new towns exhibit clear transformations over time.

In the 1990s, public rental housing floor plans were predominantly characterized by one-bay configurations, particularly in units around 30 m², arranged within linear slab-type building forms. These layouts were developed under policy-driven mass housing supply programs, such as the “Two Million Housing Units Plan,” and were shaped by regulatory constraints, including dimensional standards and building length limits. Cost efficiency and large-scale production were also critical considerations. This tendency is consistent with previous studies indicating that standardized floor plans are repeatedly applied in mass housing production [27,28], reflecting broader patterns of standardization and repetitive design.

These characteristics are evident in the dominance of combined living–sleeping spaces and the use of the kitchen–dining area as a connecting zone within the unit, forming a typical one-bay configuration. Notably, the fact that approximately 50% of the units were 30 m² one-bay types suggests that standardized layouts became the fundamental unit of early public rental housing design. While this ensured efficiency and repeatability, it also limited flexibility and diversity in spatial configuration.

In the 2000s, floor plan transformations became more pronounced. The legalization of balcony extensions marked a critical turning point, as balconies were reinterpreted as expandable interior spaces. This led to the gradual introduction of two-bay and three-bay configurations, accompanied by changes in spatial organization and width-to-depth ratios. This can be interpreted as a shift toward more clearly differentiating the spatial domains and functions according to housing size through the use of expandable balcony spaces, which is consistent with the increasing functional differentiation of residential space [29]. While small units (around 20 m²) were simplified into studio-type layouts, units larger than 30 m² began to separate living and sleeping areas. This reflects an effort to establish clearer spatial zoning by utilizing expandable balcony spaces.

In the 2010s, these trends intensified, resulting in greater diversity and complexity in floor plan typologies. With the development of second-generation new towns and the establishment of the Korea Land and Housing Corporation (LH) through institutional integration, housing design standards were reorganized and unified. This led to more systematic and detailed design criteria, while also accommodating a wider range of housing demands. As a result, two-bay configurations became standardized, and three-bay layouts were increasingly adopted, contributing to greater diversity and complexity in spatial arrangements.

Overall, public rental housing floor plans have evolved progressively from standardized one-bay layouts in the 1990s, to differentiated configurations in the 2000s, and to diversified and complex arrangements in the 2010s.

5.2. Characteristics of Floor Plan Design by Housing Size

The characteristics of public rental housing floor plans vary significantly according to housing size.

Small units (around 20 m²) tend to maintain integrated spatial configurations, evolving into studio-type layouts after the 2000s. This reflects a continued emphasis on maximizing spatial efficiency within limited floor areas.

Units around 30 m² exhibit the most significant transformation. While they were initially characterized by integrated living–sleeping spaces in the 1990s, they gradually evolved toward spatial separation, including distinct living rooms, bedrooms, and independent kitchen–dining areas. The introduction of two-bay configurations played a key role in improving spatial balance and organization.

Units around 40 m² represent a transitional stage in floor plan development. At this scale, two-bay configurations become standardized, and the separation between living spaces and bedrooms, as well as the independent organization of kitchen–dining areas, becomes firmly established. In addition, front–rear spatial zoning emerges, leading to clearer functional differentiation. This stage can be interpreted as the structural consolidation of spatial separation that began in smaller units. At the same time, decreasing width-to-depth ratios indicate a shift toward more balanced spatial proportions, forming the basis for the diversification observed in larger units.

Larger units (50 m² and above) demonstrate a significant increase in spatial diversity. With the addition of more bedrooms, floor plan configurations become more complex. In particular, the introduction of three-bay layouts allows for expanded use of front-facing space, and spatial allocation varies considerably depending on the plan type, even within the same unit size. This reflects an increasing responsiveness to diverse household types and lifestyles.

Overall, public rental housing floor plans evolve from integrated to separated and eventually to complex configurations as housing size increases. This finding is consistent with previous studies suggesting that spatial differentiation in residential layouts is closely associated with housing size [18,30].

5.3. Institutional Influences on Floor Plan Design

Unlike private housing, public rental housing floor plans are fundamentally shaped within the framework of policies and institutional regulations.

In the 1990s, standardized layouts emerged under mass housing supply policies and regulatory systems defined by the Building Act and Housing Act, emphasizing efficiency and economic feasibility.

In the 2000s, institutional changes such as the legalization of balcony extensions directly influenced spatial configurations, facilitating greater functional differentiation.

In the 2010s, following institutional integration, housing design standards were reorganized, leading to a coexistence of standardization and diversification. This reflects a structural condition in which deregulated legal frameworks coexist with more detailed design guidelines, resulting in increasingly complex spatial configurations.

These changes can be interpreted through the lens of path dependency [31,32]. Rather than being entirely replaced, early standardized one-bay layouts were gradually transformed and adapted over time. This indicates that public rental housing floor plans are not merely design outcomes but are institutionalized spatial forms shaped and reproduced through regulatory frameworks. Moreover, this demonstrates that floor plan design in public rental housing operates as a dynamic system continuously influenced by institutional conditions. Furthermore, these findings suggest the need for more flexible floor plan strategies to respond to changing demographic structures and diverse lifestyles. In future public rental housing design, it will be important to move beyond standardized, criteria-driven approaches and adopt adaptable and flexible design strategies that can better reflect user needs.

5.4. Contributions and Implications

This study makes several academic and practical contributions compared to previous research on public rental housing.

First, it provides a comprehensive longitudinal analysis of floor plan evolution over approximately three decades, rather than focusing on a single period or case. This allows for an integrated understanding of the transformation from standardized one-bay layouts to diversified two- and three-bay configurations.

Second, by examining floor plan characteristics in relation to housing size, this study identifies a structural progression from integrated to separated and ultimately to complex spatial configurations. This contributes to generalizing patterns that have previously only been discussed in isolated case studies.

Third, this study interprets floor plan design within the context of policy and institutional frameworks, demonstrating that spatial configurations are not merely architectural outcomes but are shaped by regulatory systems. In particular, it highlights the role of institutional factors such as balcony extension policies, design standards, and public housing guidelines in shaping spatial organization.

Fourth, by applying the concept of path dependency, this study explains how existing floor plan types are not entirely replaced but are gradually transformed and reproduced over time, offering a useful theoretical framework for understanding public housing design.

Finally, unlike previous studies that have focused on individual cases or specific periods, this research provides an integrated explanation of the long-term structural transformation of public rental housing floor plans, thereby offering a clearer understanding of their evolution and underlying mechanisms.

5.5. Limitations and Future Research

This study focuses on analyzing the relationship between floor plan design and legal and institutional factors in public rental housing; therefore, user experiences and social and behavioral aspects were not included within the scope of the analysis. In addition, the case samples are limited to specific periods and new towns, which poses a limitation in terms of regional scope. Future research should aim to incorporate user behavior and residential experiences to provide a more comprehensive and integrated analysis. Furthermore, as this study primarily focuses on institutional and spatial transformations, future research could consider broader perspectives, including sustainability, evolving socio-cultural dynamics, and comparative analyses in international contexts. Such extensions would provide a more comprehensive understanding of public rental housing design in response to changing societal conditions.

6. Conclusions

This study examined the characteristics of changes in the floor plans of public rental housing in Korean new towns by analyzing floor plan elements according to construction period and unit size, as well as the related legal and institutional frameworks that influenced the planning process. Through this analysis, it was confirmed that the evolution of public rental housing floor plans has been shaped not only by design improvements but also by policy objectives and institutional frameworks.

In the 1990s, elongated floor plans with a one-bay structure centered on the combined living and sleeping space were commonly developed under dimensional regulations and building length restrictions. In the 2000s, following the legalization of balcony expansion, floor plan types adopting two-bay and three-bay structures began to diversify. In the 2010s, floor plan types became further subdivided according to district unit plan regulations and detailed design guidelines of public institutions, and they diversified as the unit size increased.

Overall, legal regulations such as the Building Act, the Housing Act, and the architectural design guidelines of public institutions have played a key role in shaping the fundamental configuration of floor plans by defining the arrangement of the living room, the minimum dimensions of rooms, and the range of balcony expansion. As a result, the floor plans of public rental housing in Korea have been structured largely by institutional standards and supply policies rather than evolving naturally through market demand, as seen in privately sold apartments.

Over the past 30 years, public rental housing in Korea, similar to many other Asian countries, has been supplied through large-scale development projects in new towns. While this supply approach has provided affordable housing opportunities for low-income households, it has also raised continuous debates regarding the quality of residential environments. Therefore, to achieve meaningful improvements in the quality of public rental housing floor plan design, it is necessary to enhance the flexibility of internal design guidelines and establish planning standards that can respond adaptively to diverse housing types and changing lifestyles. Furthermore, it is essential to achieve a balance between legal and institutional standards and design autonomy, and to shift toward design frameworks that more actively reflect user needs. This suggests that public rental housing should be understood not merely as a means of supply, but as a living environment that must consider residents’ lifestyles and the quality of residential space.