Affordable Housing in Developing Regions: A Systematic Review of Materials, Methods and Critical Success Factors with Case Insights

Abstract

Rapid urbanization in developing regions presents a critical challenge to the provision of affordable housing. This systematic review, conducted following the PRISMA 2020 guidelines, analyzed 91 studies (2013–2024) from Scopus and Google Scholar to identify cost-effective materials and innovative techniques suitable for the developing context. Findings reveal that achieving affordability in developing regions requires a holistic approach that integrates material innovation with human capacity building. The analysis of critical success factors (CSFs) in the Rumah Unggul Sistem Panel Instant (RUSPIN) system from Indonesia and the Recycled Plastic Formwork (RPF) system from South Africa exemplifies this integration. Both systems show high potential for scalability and technological transfer using local materials and labor training. The review also highlights that materials commonly used in developed countries (e.g., autoclaved aerated concrete, expanded polystyrene, and light steel gauge framing) face adoption barriers in developing regions due to challenges related to supply chains, industry capacity, and regulatory frameworks. Conversely, locally available materials (e.g., earth, bamboo, and recycled waste) require ongoing research to enhance their availability and structural performance. Ultimately, achieving affordable housing depends on an integrated approach that combines locally sourced materials, innovative construction techniques, and the strategic application of critical success factors.

1. Introduction

1.1. Background

Urbanization is rapidly reshaping the twenty-first century, with the world’s urban population expected to nearly double by 2050. About 2.5 billion additional people—90% from Africa and Asia are expected to move to cities [1]. By 2070, about 58% of world population will be urban; however, without adequate infrastructure, housing, and effective urban planning, this rapid expansion could exacerbate congestion and strain urban systems [1]. In developing regions, high vulnerability to natural disasters further underscores the need for safe, resilient affordable housing.

Given that cities face immense sustainability challenges, there is an urgent need to promote adequate, safe and affordable housing and to upgrade slums and informal settlements in order to build inclusive, resilient and sustainable cities [2]. In developing regions, low-income families struggle to afford housing [3] due to weak urban planning and policies, insufficient subsidies, and rapid urban migration [4,5]. Since 1976, the United Nations [2] has worked to improve adequate standard of living and address the lack of basic services [4], while climate change continues to intensify these risks. In 2016, inadequate sanitation contributed to 829,000 diarrheal deaths, and household air pollution caused 3.8 million fatalities [6,7]. Despite affordable housing being essential for global health, 80% of urban residents still lack adequate housing [8], requiring approximately 96,000 new affordable homes daily to meet demand [9]. Recognizing these challenges, Sustainable Development Goal (SDG) 11 and the World Bank–GFDRR Building Regulation emphasize inclusive and sustainable urban development, shifting the focus from reactive disaster response to proactive risk reduction [10].

Research across urban planning, public health, economics, and housing policy identifies construction costs as the primary barrier to affordable housing delivery in developing countries [11,12,13], Materials and construction labor account for 60–80% of total housing costs, making cost-effective solutions essential for improving accessibility [14,15,16,17]. However, most developing countries face a fundamental dilemma: choosing between expensive imported materials and locally available alternatives that often lack proven safety and durability standards.

While research on this topic is expanding, it remains fragmented, often limited to specific materials, construction techniques, or individual countries, hindering knowledge transfer between regions facing similar challenges. This review addresses these gaps by systematically analyzing cost-effective construction materials and methods across multiple developing countries. Using the Critical Success Factors (CSFs) framework proposed by Moghayedi et al. [18], it examines successful case studies to provide actionable insights based on four key factors: (1) local adaptability, (2) supply chain independence, (3) cost efficiency, and (4) integration with human resource development. The findings aim to identify the core drivers of successful affordable housing implementation in developing countries.

1.2. Related Review

While numerous studies discuss affordable housing construction, few provide comprehensive reviews across multiple developing regions. This gap likely stems from significant variations in structural loading conditions and economic disparities, which complicate direct cross-national comparisons and lead to fragmented research. Recent reviews, as summarized in

Table 1. Recent Reviews of affordable housing policies, construction materials and techniques.

Reference	Year	Focus Area	Geographic Scope
[19]	2013	Earth blocks in social housing	Africa, Asia, Latin America
[20]	2017	Earthen materials and technologies in housing projects	Africa
[21]	2020	Local innovation potentials for concrete materials derived from indigenous materials.	Africa
[18]	2021	SIAH Critical Success Factor Framework	South Africa
[22]	2023	Scientometric analysis of affordable housing construction in developing countries	Developing countries
[23]	2024	Potential of local materials for sustainable constructions	Morocco
[24]	2025	Integrating traditional knowledge with modern construction techniques	India

, have examined affordable housing materials and techniques across regions; however, most focus on specific material types or a single continent or country. Others have developed frameworks, such as the CSFs for South Africa. Nonetheless, this narrow scope fragments knowledge, limiting the cross-regional transfer of successful strategies and hindering a holistic understanding of affordable construction systems.

1.3. Objectives and Research Questions

To overcome fragmented knowledge and address research gap, this review aims to (i) synthesize evidence (2013–2024) on affordable housing materials and methods using a unified classification framework, (ii) map them to performance, cost, and implementation barriers, (iii) identify innovative, successful case studies and their critical success factors, and (iv) provide actionable recommendations for future research. Hence, we address the following key questions:

• Q1: What locally available and innovative materials are used for affordable housing?
• Q2: What innovative construction approaches have been applied in successful affordable housing projects?
• Q3: Are there successful examples of affordable housing projects in developing countries that could inform best practices for materials, construction methods and policy?
• Q4: What are the CSFs for constructing affordable housing in developing countries?

The methodology is outlined in Section 2. Section 3 presents key findings on construction materials and techniques; Section 4 discusses construction materials for affordable housing; Section 5 explores construction approaches; and Section 6 highlights a notable case study of successful affordable housing projects and their critical success factors. Finally, Section 7 provides concluding remarks and future research recommendations.

2. Methodology

2.1. Review Design and Protocol

We conducted a systematic review following the PRISMA 2020 guidelines to address the research questions defined in Section 1.3 [25]. A PICO (Population, Intervention, Comparator, Outcome) framework, presented in

Table 2. PICO logic for affordable building strategies.

PICO Element	Description
Population	Low-income households in developing countries, particularly in urban informal settlements and rural areas
Intervention	Locally available and alternative construction materials and methods
Comparison	Standard construction practices currently used in developed regions
Outcome	Critical success factor for affordable housing case study implementation

, was used to translate these research questions into eligibility criteria for study selection and data extraction.

2.2. Classification Framework for Analysis

To systematically analyze the literature, this review classifies construction materials and techniques using the framework summarized in Figure 1.

Construction materials are first categorized based on their structural function into load-bearing and non-load-bearing types. Load-bearing materials, such as reinforced concrete, steel, and structural timber, support the building’s weight and transfer loads to the foundation, ensuring structural stability. In contrast, non-load-bearing materials such as earth, polystyrene foam, and glass are primarily used for partitions or exterior walls.

Additionally, construction techniques are classified into dry and wet methods based on their primary joining process. Dry construction involves prefabricating core building components in a factory or on-site with minimal or no use of water, assembling them with bolts, nuts, and other fasteners without mortar or wet binding agents [26]. In contrast, wet construction requires on-site joining of components using materials such as concrete, mortar, plaster, or grout The classification of materials and techniques used across the different case studies is detailed in Appendix A.

2.3. Finding Relevant Studies

A systematic search of literature published between 2013 and 2024 was conducted using two primary academic databases: Scopus and Google Scholar. The search was limited to peer-reviewed journal articles and conference papers published in English within the field of engineering. A structured query with keywords related to affordable housing, construction materials, and construction techniques was employed. The specific search queries and the number of documents retrieved from each database are presented in

Table 3. Search query for research on affordable housing construction.

Search Query	Search Database	Total Number of Studies
(TITLE-ABS-KEY ((low-cost housing) OR (affordable housing) OR (cost efficient housing)) AND ((Material) OR (alternative material) OR (locally available material)) AND ((construction) OR (alternative construction)))	Scopus	1094
TITLE-ABS KEY (((Affordable-Building) OR (Affordable-Housing) OR (Affordable-Dwelling)) AND ((Materials AND case-study) OR (Construction AND case-study) OR (Policy AND case-study) OR (thermal comfort AND case-study)))	Scopus	462
“Affordable housing” AND “material” AND “construction techniques” AND “residential building” AND “housing policy”	Google scholar	246

.

2.4. Study Selection

The study selection process is illustrated in Figure 2. The initial search identified 1802 papers from Scopus and Google Scholar. After applying exclusion criteria, publication year, subject relevance, document type, language, and duplication, the dataset was reduced to 559 articles for screening.

During the screening of titles and abstracts, 456 papers were excluded based on predefined criteria. A significant number were removed because their geographical focus was on developed countries (n = 254). Further exclusions were made for studies whose scope was unrelated to this review’s focus on construction materials and techniques, such as those centered on urban design, spatial standards, or social assistance (n = 71). Additionally, papers addressing sustainable building solutions not directly linked to affordability, for example, those focusing solely on thermal comfort or housing policy were excluded to maintain a clear focus. This phase left 103 papers for a more detailed review.

At this stage, 14 additional papers from the Google Scholar search were incorporated to ensure comprehensive analysis, bringing the total to 117 articles for full-text eligibility assessment. During the full-text review, a further 26 articles were excluded because they focused on non-residential buildings (n = 21) or lacked sufficient methodological clarity and detail (n = 5). This process resulted in a final dataset of 91 studies deemed relevant for comprehensive analysis.

3. Research Trends and Distributions

3.1. Research Trend by Year and Regions

Figure 3a illustrates the annual publication trends during the review period (2013–2024). The increasing number of publications in the latter half of the decade indicates growing academic and practical interest in affordable housing construction across developing regions.

Figure 3b shows the geographical distribution of these studies. Research is predominantly concentrated in Sub-Saharan Africa and Southeast Asia, with a notably high number of publications originating from countries such as India, Indonesia, and Nigeria. Africa accounts for approximately 35% of the studies, while Asia contributes around 65%. This concentration reflects the urgent demand for affordable housing and the rapid pace of urbanization in these regions. In contrast, other areas with significant housing needs, such as Latin America, remain relatively underrepresented in the literature.

3.2. Research Trend by Focus Area and Building Type

Figure 4a categorizes the reviewed studies by research focus. Studies concentrating solely on construction materials account for the largest share (39%), followed by those examining both materials and methods (36%), and studies addressing the integration of various construction techniques (21%).

Figure 4b illustrates the types of housing projects examined. Detached houses represent the predominant type, comprising 41% of the studies, while multi-story collective housing and semi-detached houses account for 15% and 8%, respectively. This distribution indicates research focus on individual housing units, likely because large-scale, high-rise housing demands advanced structural performance and typically relies on conventional materials and methods used in developed countries. Consequently, opportunities for developing context-specific innovations are more prevalent in low-rise housing, explaining its stronger representation in the affordable housing literature of developing regions.

3.3. Distribution of Studies by Materials and Construction Method

Figure 5a illustrates the distribution of the reviewed studies based on the classification framework detailed in Section 2.2. Regarding construction materials, non-load-bearing materials are the most frequently studied, representing 52% of the literature. In comparison, load-bearing materials, such as concrete and steel are examined in 14 studies (35%).

In terms of construction methods, wet construction dominates the literature (Figure 5b), with significantly more studies than dry construction. This preference may be linked to its historical prevalence, local material availability, and well-established traditional practices in developing regions. The relatively limited research on dry construction highlights an area with strong potential for further investigation, particularly given its advantages in speed and standardization for large-scale projects.

4. Construction Materials for Affordable Housing

Construction projects require various resources, with materials accounting for 30% to over 50% of total costs [27,28,29,30,31], significantly influencing construction techniques, labor expenses, and project duration. This section discusses the key cost-effective materials identified in the reviewed literature, categorized by structural function, as defined in Section 2.2 into load-bearing and non-load-bearing types. The analysis focuses on their characteristics, advantages, and the challenges associated with their application in developing regions.

4.1. Load Bearing Materials

Load-bearing materials are essential for ensuring the structural integrity of buildings. Known for their durability and versatility, they are widely used in both structural and decorative applications [32].

4.1.1. Concrete and Its Supplementary Materials (SCMs)

Concrete is one of the most widely used load-bearing materials globally. While the cost of fine aggregates (sand) and coarse aggregates varies by source and country, the high cost and carbon emissions associated with cement pose sustainability and affordability challenges [33]. This has driven interest in developing countries toward more cost-effective and environmentally friendly alternatives for cement, aggregates, and reinforcement. The African continent, for instance, possesses a wide range of locally available raw materials and techniques that can reduce reliance on cementitious materials and promote low-carbon construction through vernacular building methods [34].

In developing countries, supplementary cementitious materials derived from agricultural, industrial, and construction byproducts offer cost-effective substitutes. These materials not only reduce CO₂ emissions [35] but also lower construction costs while utilizing waste [36]. Fly ash, a byproduct of coal combustion, is abundant in countries such as India and South Africa yet remains underutilized. When properly processed, it can replace fired clay bricks [37,38] or partially substitute cement in concrete [39]. Fly ash can also be incorporated into sand-lime or cement mixtures to produce bricks with compressive strengths ranging from 40 to 80 kg/cm² (approximately 4–8 MPa) [40].

Gypsum, a byproduct of the power and fertilizer industries, is another low-cost material commonly used in cement production. Glass Fiber Reinforced Gypsum (GFRG) panels have been successfully applied in walls and slabs for affordable housing in several countries [41,42]. Rice husk ash (RHA), a waste product from rice milling, an industry prevalent in many developing regions has high pozzolanic properties and can replace 10–20% of cement in concrete mixes [43,44,45]. Other agricultural and industrial ashes, including corn cob ash (CCA), corn husk ash, corn stalk ash, sawdust ash (SDA), wood ash, coconut shell ash, palm oil fuel ash (POFA), sugarcane bagasse ash (SCBA), and neem seed husk ash (NSHA), have also shown potential as partial cement replacements [46].

Coarse aggregates constitute 70–80% of concrete volume, and their cost and availability significantly influence overall construction expenses. In many developing regions, partial replacement with locally sourced, low-cost alternatives such as coconut shells, periwinkles, palm kernel shells, and construction and demolition (C&D) waste offers a promising pathway for cost-effective and sustainable housing, benefiting low-income families [47]. In India, concrete mixed with 50% C&D waste achieved a compressive strength of 29.8 MPa at a lower cost, with C&D waste panels proving the most economical compared to conventional concrete and brick walls, with a cost ratio of Rs. 1022:840:750, respectively [48]. Ogundipe et al. (2021) suggested that up to 15% replacement of granite with palm waste shells (PWS) or palm kernel shells (PKS) is suitable for non-load-bearing components, and up to 5% for load-bearing structures, without compromising structural integrity [49].

4.1.2. Steel and Its Supplementary Materials (SCMs)

Steel represents another key category of load-bearing materials in contemporary building construction, valued for its structural strength and performance. The types of steel used in construction are generally categorized by their forming processes into hot-rolled steel, fabricated steel, cold-formed steel, and cast steel [50].

In developed countries, steel is widely used for its strength and efficiency. However, in many developing regions, particularly across Africa and parts of Southeast Asia, its use remains limited due to high production costs and a shortage of skilled labor. Although several African countries possess substantial iron ore resources, the absence of domestic steel processing facilities necessitates reliance on costly imports [29].

In contrast, countries such as China and India have developed domestic steel industries that meet both local and regional demand [51], enabling the adoption of Light Gauge Steel Framing (LGSF) systems in urban development, disaster relief, and prefabricated housing projects [52]. Despite its technical and environmental advantages, LGSF adoption in developing regions is constrained by limited technical capacity, inadequate skilled labor, weak regulations, and cultural barriers. The Indonesian case study highlights its advantages, including faster, cost-effective, and sustainable construction [52,53]. This indicates that with improved accessibility and local adaptation, LGSF could become a scalable solution to housing shortages in developing countries.

Fibers from renewable plants are often used as supplementary reinforcement materials in concrete, valued for their eco-friendliness, strength, sustainability, and cost-effectiveness in construction [54]. Hemp, a prime example, is employed in high-quality insulation materials and offers advantages such as high tensile strength, thermal resistance, and cost reduction of up to 20% [39]. It is also used in the production of hempcrete [50]. Its performance can be improved by adding fly ash, aluminum, or lime powder, replacing 50% of the aggregate with construction waste, and incorporating 0.1% fiber by cement weight [39]. However, in flood-prone areas, applications of hempcrete require adaptations such as elevated plinths and waterproof coatings [55].

Furthermore, Textile Reinforced Concrete (TRC) combines synthetic and natural fibers with fine-grained mortar to provide a durable, lightweight, and corrosion-resistant alternative to conventional reinforced concrete [56]. Similarly, materials such as steel wire mesh, bamboo, old car tire strips, polypropylene (PP) mesh, cotton canvas sheets, and glass fiber-reinforced plastic strips are used as reinforcements, particularly to strengthen unreinforced masonry. Their application generally involves the use of cement or adhesives to ensure effective bonding and structural enhancement [57].

Bamboo is a highly renewable and locally available material in many developing regions. Its tensile strength—estimated at 50–75% that of steel [58]—along with its lightweight, flexibility, durability, and cost-effectiveness, makes it particularly suitable for affordable housing applications [32], including in areas prone to earthquakes [55], tsunamis [28], and floods [24]. It can also serve as a substitute for reinforcement in concrete [59]. For instance, Dalbiso and Addissie and Barbhuiya et al. demonstrated bamboo’s suitability in beehive-shaped Sidama houses in Ethiopia [60] and Assam-type houses in India [55], respectively. These characteristics make bamboo adaptable to various construction methods discussed in Section 5. However, challenges to bamboo adoption in developing countries include limited awareness and the need for improved treatment techniques to enhance durability [55].

4.2. Non-Load-Bearing Materials

Non-load-bearing materials are construction elements that do not support structural loads beyond their own weight but play essential roles in partitioning spaces and enclosing buildings. Traditionally, materials such as wood, gypsum board, bricks, and lightweight concrete have served this purpose. In recent years, however, there has been growing interest in developing new materials and finding innovative applications for traditional ones to enhance cost efficiency and environmental performance.

4.2.1. Earth Based Materials

Earthen materials—including soil, stones, rocks, and timber [61]—are commonly used for walls, floors, and small retaining structures. They are valued for their thermal insulation, local availability, and low environmental impact and have long been among the most cost-effective building materials, particularly in regions such as Africa, Asia, and Latin America. Their natural origin, accessibility, and minimal processing contribute to affordability, eco-friendliness, and superior thermal comfort [20], while maintaining the minimum functional and safety standards required for a building’s intended use [62]. However, due to their sensitivity to water and relatively low strength [63], additional strengthening or reinforcement is necessary for these structures to resist earthquakes, minor landslides, and other natural hazards [28].

Recent advancements in earthen materials across many developing countries include compressed earth blocks (CEB), compressed stabilized earth blocks (CSEB), interlocking stabilized soil blocks (ISSB) [19,64], and earth/sandbag technologies [30,65]. However, their successful adoption and structural performance depend on proper soil selection, production methods, and skilled labor [31]. Despite their advantages, these materials remain underutilized in social housing—often due to regulatory, logistical, or perception-based barriers—even though they offer versatile finishes and provide cooler interiors than conventional cement block structures [16].

Karshif, a natural stone composed of salt, clay, and sand found along the shores of salt lakes, is primarily used in parts of North Africa and the Middle East, particularly in Egypt’s Siwa Oasis. It is valued for its environmental, social, and economic sustainability. However, its weak structural strength and vulnerability to rainfall significantly limit its long-term durability. To overcome these challenges, Mohamed F.A. proposed combining Karshif with modern materials such as reinforced concrete structural elements to enhance its resilience while preserving the oasis’s unique architectural character [66].

4.2.2. Lightweight Panel Materials

Lightweight panels such as Expanded Polystyrene (EPS), Autoclaved Aerated Concrete (AAC), and sandwich panels are ideal for walls, partitions, roofing, and prefabricated structures. They offer fast installation, reduced structural load, and improved energy efficiency. EPS, composed of 98% air and 2% polystyrene, is extremely lightweight yet provides good insulation; when combined with concrete, it becomes more durable and resistant to flooding and cyclic loading, making it suitable for flood-prone areas. Its lightweight nature also reduces the building’s dead load, thereby lowering overall construction costs [67]. EPS can further serve as a lightweight aggregate in concrete mixes, partially or fully replacing traditional aggregates [68].

Similarly, AAC is a lightweight concrete composed of silica sand, cement, lime, fly ash, gypsum, aluminum powder paste, water, and an expansion agent [69,70]. Although both EPS and AAC are widely used in developed countries, their adoption in developing regions remains limited due to high costs, weak regulatory enforcement, and limited local production capacity [71]. Recent studies [68,71] emphasize the need for greater awareness and education to promote the safer and broader adoption of these technologies.

4.2.3. Recycled Plastic Materials

Recycled materials are increasingly used in walls, paving, infill, and other non-load-bearing structures to promote sustainability. For instance, plastic and beer bottles, traditionally regarded as waste, possess structural properties and dimensions suitable for construction applications [72]. In developing countries, polyethylene terephthalate (PET) bottles are widely used as substitutes for conventional concrete or adobe walls [73].

These repurposed materials can be utilized in various forms, including bottle-brick masonry, PET bottle panels, Polli Bricks [73], and sand-filled plastic bottle clay panels [74]. Additionally, plastic has been applied in roof insulation, foundation reinforcement [75], and plastic bricks [76].

Integrating such waste materials into construction helps conserve natural resources, reduce environmental waste, and lower costs for sustainable, affordable housing [75,76]. However, the non-biodegradable nature of plastic poses ongoing environmental challenges [75], underscoring the need for proper implementation and long-term management.

5. Construction Approaches for Affordable Housing

The adoption of efficient construction techniques is essential for addressing affordable housing challenges, as they directly influence project duration, costs, and structural resilience [77]. Low-cost housing frequently faces issues such as poor workmanship, underscoring the need for solutions that incorporate durable framing, proper connections, and high-performance materials [55,78]. This section examines how the properties of the materials discussed in Section 4 align with specific wet construction methods illustrated in Figure 6 and dry construction methods illustrated in Figure 7, are commonly used in developing countries, highlighting the crucial relationship between material selection and construction technique.

5.1. Wet Construction

5.1.1. Masonry Construction

Masonry construction involves stacking and binding materials such as bricks, stones, or concrete blocks with mortar. In developing countries, cost-effective local techniques like Compressed Stabilized Earth Blocks (CSEBs) [79] can reduce expenses significantly, with an average cost of about $15,000 compared to $35,000 for conventional housing [64]. Similarly, the Rat-Trap Bond masonry technique [27] offers 10–15% savings in labor costs, 25% savings in material costs, and provides an esthetically appealing finish [82].

However, most masonry buildings in developing regions are not designed to carry significant structural loads or withstand natural disasters. Weak wall materials and the absence of proper engineering design often make them unsafe in seismic zones [83]. Nevertheless, their resilience can be enhanced through stabilization, repair, strengthening, and seismic retrofitting measures [57,84,85].

5.1.2. Cast-Situ Construction

Cast-in situ concrete construction involves mixing, casting, and molding concrete directly on-site into formwork for walls, floors, or columns, where it cures and hardens in its final position. In developing countries, this method is advantageous due to its cost-effectiveness and reliance on local labor; however, quality control and technology transfer remain major challenges.

The tunnel form system, a box-shaped steel formwork used to cast reinforced concrete (RCC) walls and slabs monolithically within 24 h, shares similarities with the RPF system, which employs reusable plastic formwork—capable of up to 50 reuses [86]. Despite high initial investment costs, these systems are economical for large-scale, multi-story housing projects in countries such as India, South Africa, Nigeria, Egypt, and Indonesia. Nevertheless, studies in India have identified challenges including limited technology transfer, inadequate worker training, high costs, and restricted access to advanced machinery [87].

Flat slab systems, supported directly by columns without beams, are increasingly used in urban areas of developing countries such as India, Nigeria, Kenya, Egypt, and Indonesia, following their success in developed nations. This technology can reduce costs by up to 19.9% [88,89]. Similarly, 3D printing construction technology accelerates building processes, reduces labor costs, and minimizes waste [55]. It shows great promise for low-cost, sustainable housing and rapid disaster recovery in developing countries that utilize local, low-carbon materials [55,63]. However, widespread adoption remains constrained by high equipment costs, material durability issues, regulatory gaps, and inadequate infrastructure [63].

5.2. Dry Construction

Precast concrete construction, or prefabricated construction, involves manufacturing standardized structural components in a factory and assembling them on-site [90]. These systems are highly efficient in resisting rotations, displacements, and distortions due to their rigid beam–column connections [91]. Widely used in both developed and some developing countries, precast panels are valued for their speed, quality, and cost efficiency. Although adoption in developing regions remains limited due to high initial setup costs and technical challenges, they are applied in shear walls, modular homes, and roofing systems [92,93,94,95], offering adaptability for affordable and disaster-resilient housing [96].

Bamboo strips, when cut, treated, and woven into a mesh before being embedded in cement mortar, can form a 50 mm thick wall panel that is 56% lighter and 40% cheaper than traditional brick walls while offering superior earthquake resistance [97]. This technique is common in Indonesia, India, Ethiopia, Kenya, and Nigeria due to bamboo’s local availability, affordability, and suitability for sustainable construction. Strength can be improved through house smoking [60] and modern chemical or natural curing treatments [58,98], while durability is enhanced using alternative jointing methods such as ropes, nuts, and bolts [98].

Interlocking construction methods use dry-jointed connections between components, eliminating the need for mortar or adhesives while achieving structural integrity through geometric interlocking. For example, Interlocking Stabilized Soil Blocks (ISSBs), discussed in Section 4.2.1. can reduce construction costs by up to 40%. This system has been implemented across Africa, Asia, and Mexico, often with reinforced frames and elements for added stability [99], though additional design considerations are required in seismic regions [19]. Variants include coconut fiber–reinforced concrete interlocking blocks [100] and designs incorporating date palm midrib components [79]. Reinforcing ICSEB columns can increase strength by 23% for single walls (125 mm) and 58% for double walls (250 mm), with greater wall thickness further enhancing load-bearing capacity [101]. These advancements enable the construction of earthquake- and storm-resistant ISSB structures in developing countries.

Sandbag technology, shown in Figure 7a, uses sand-filled polypropylene or burlap bags reinforced with barbed wire or mesh and sometimes coated with plaster or lime to form eco-friendly, disaster-resistant walls suitable for low-cost housing. Despite its economic and environmental benefits, including fire and earthquake resistance, social acceptance remains limited in both developed and developing countries [65].

Furthermore, panel construction methods such as Glass Fiber Reinforced Gypsum (GFRG) (Figure 7b), also known as “Rapid Wall” (RW) [81], and Expanded Polystyrene (EPS) panels [68,102], represent hybrid construction techniques that combine precast elements with cast-in situ processes such as concrete, shotcrete, joint grouting, or plastering. These panels are widely used in developed countries due to their flexibility, fire resistance, and water-resistant properties. However, their adoption in developing countries is often constrained by economic limitations, restricted access to manufacturing technology, regulatory challenges, and limited awareness. Despite these barriers, they are increasingly being used in India for pilot residential projects [41].

6. Successful Implementation

6.1. RUSPIN Construction Method

While precast concrete systems are widely recognized in developed countries for their efficiency, shorter construction times, and cost advantages, their large-scale implementation in developing regions for affordable housing has historically faced significant challenges. These obstacles primarily arise from technical complexities, high initial investment in heavy machinery, and a shortage of skilled operators, as discussed in Section 5.

RUSPIN (Rumah Unggul Sistem Panel Instant), an innovative dry-joint precast concrete modular construction system developed by Indonesia’s Ministry of Public Works and Housing (PUPR), directly addresses these constraints through a comprehensive approach tailored to the specific conditions of developing countries [103]. As shown in Figure 8, RUSPIN has demonstrated remarkable success in reducing construction time and costs while enhancing structural resilience, particularly in disaster-prone areas. This system exemplifies the practical application of precast concrete (discussed in Section 4.1) through dry construction and modular approaches (outlined in Section 5.2).

6.2. Reusable Polymer Formwork (RPF) Construction System

The Reusable Polymer Formwork (RPF), also known as the MOLADI construction system, is an innovative building technology developed in South Africa to address key challenges related to affordability, durability, sustainability, skill shortages, and limited resources and funding in developing countries [104]. The system employs a removable, reusable, recyclable, and lightweight formwork mold filled with an approved aerated mortar to form the wall structure of a house [105]. The aerated mortar, comprising graded river sand, cement, water, and a chemical additive called ‘RPF Chem’, produces a high-quality, monolithic wall that typically requires no plastering [86,104].

The primary objective of the RPF system is to minimize construction waste and reduce construction time using monolithic plastic formwork panels, which can be reused up to 50 times, enhancing both efficiency and cost-effectiveness. Although originally developed in South Africa, the system has been adopted in more than 26 countries, including 16 developing nations, for various affordable housing projects ranging from single-unit homes to mass and multi-story constructions, as illustrated in Figure 9. Moreover, the system offers earthquake resistance, making it suitable for disaster-resilient housing [104]. This system exemplifies the practical application of masonry and wet construction methods discussed in Section 5.1.

6.3. Critical Success Factors of RUSPIN and RPF Construction System

Critical Success Factors (CSFs) are defined as key priorities or performance elements essential for achieving overall project success [108]. In the context of Sustainable Innovative Affordable Housing (SI-AH), CSFs represent the factors that significantly influence the effective design, construction, and operation of housing units [18]. Both the RUSPIN and RPF construction systems owe their success to strategies such as local adaptability, supply chain independence, cost efficiency, and integration with human resource development. Although their technological approaches differ, their core philosophies are remarkably similar. Recognizing these CSFs is particularly crucial for ensuring the transferability and replication of successful affordable housing models across other developing regions. A comparative analysis of the RUSPIN (Indonesia) and RPF (South Africa) construction systems is presented in

Table 4. Comparative analysis of RUSPIN method and RPF construction systems.

Feature	RUSPIN System (Rumah Unggul Sistem Panel Instant)	RPF System
Origin	Indonesia	South Africa
Main developer	Government Initiative	Private developer
Design Initiatives	Developed to address local constraints using lightweight, human-portable panels that do not require heavy machinery for transport or assembly	Designed to integrate with readily available local materials, reducing transportation costs and environmental impact
Core Technology	Two types of standardized precast concrete panels and wall infill	Reusable plastic formwork for monolithic concrete structure
Primary Material	Concrete, reinforcement	Cement mortar, reinforcement.
Joining Method	Bolt–nut connection for prefabricated panels (dry construction)	In situ cast (wet construction)
Labor and training Requirement	Requires skilled labor, though training needs are minimal	Requires unskilled or semi-skilled labor with limited training
Cost per unit house	Approx. USD 2454.94 for a 36 m2 unit	Approx. USD 6037 for a 40 m2 unit
Construction Time	1–3 weeks per unit	Around 1 week per unit
Key Advantage	Portable panels, rapid installation, cost-effectiveness, and earthquake resilience	High construction speed, cost-effectiveness, durability, and earthquake resistance
Portability	Panels are human-portable and manually transportable	Lightweight formwork easily transported to remote areas
Scalability potential	Currently implemented in Indonesia with strong potential for adoption in other developing regions	Used for decades and adopted in multiple developing countries across Asia, Africa and Latin America

.

6.3.1. Local Adaptability of the Construction Methods

The RUSPIN and RPF systems achieve success by adapting to the local constraints of developing regions. Although they employ different technologies, both utilize locally available materials such as concrete and eliminate the need for heavy machinery. RUSPIN components can be manufactured by local small-scale enterprises and are specifically designed as Panel 1 and Panel 2, which can be manually transported and assembled (see Figure 8a) [109]. This decentralized production approach significantly reduces transportation costs while promoting local economic activity and job creation.

In contrast, the success of the RPF system lies in its seamless integration with local conditions and materials. Its lightweight components can be easily transported to remote and rural areas [104]. The resulting structures are robust and resilient to environmental factors such as earthquakes, enhancing the system’s adaptability in regions prone to natural disasters.

6.3.2. Supply Chain Independence

The RUSPIN and RPF systems address supply chain challenges by prioritizing self-reliance and minimizing external dependencies. RUSPIN employs decentralized production, reducing reliance on complex international supply chains and enhancing resilience against market fluctuations. Similarly, RPF minimizes dependence on bricks, blocks, or timber by using plastic formwork that can be reused up to 50 times [86]. This supply chain independence enhances cost efficiency and reduces vulnerability to disruptions, price fluctuations, and shortages of imported building materials, common challenges in many developing countries.

6.3.3. Cost Efficiency of the Construction Method

The RUSPIN and RPF systems achieve cost efficiency through speed and material optimization. The RUSPIN system can be assembled within 1–3 weeks, with panel installation completed in a single 8 h workday. The total construction cost for a RUSPIN house is approximately 40 million IDR (USD 2454.94), comprising 22 million IDR for structural panels and 18 million IDR for architectural finishes. On average, the cost per square meter ranges from 2 to 3 million IDR, depending on customization and project scale. Considering that the average annual minimum wage in Central Java province in 2023 was about 26.4 million IDR, the cost of a single RUSPIN house is roughly 1.5 times the annual income of a minimum wage worker.

Similarly, the RPF system achieves cost reduction by amortizing the initial investment in its reusable plastic formwork over multiple projects, cutting material waste and labor costs by up to 35%. A 40 m² housing unit can be completed within one week at an estimated cost of USD 6037, though expenses may vary based on local factors such as labor rates, soil conditions, and project scale [86].

6.3.4. Integration with Human Resource Development

The RUSPIN and RPF systems excel in human resource development and job creation by transforming housing projects into opportunities for community empowerment. The RUSPIN construction method incorporates a comprehensive training program for workers, building local technical capacity, addressing skilled labor shortages, and ensuring consistent construction quality. Similarly, the RPF system simplifies the construction process, enabling unskilled workers to be trained in just two days by a single foreman [86,104]. Once trained, local laborers, contractors, or developers can operate as independent distributors of the RPF technology, receiving ongoing technical and sales support that fosters localized growth and knowledge transfer in developing regions.

6.4. Evolution and Regulatory Compliance of RUSPIN and RPF Construction Systems

The widespread implementation of the RUSPIN method and RPF system has been the result of over two decades of continuous development, refinement, and credibility-building through numerous housing projects. Both systems have evolved significantly, gaining recognition and trust to support large-scale adoption.

The RUSPIN system originated from its predecessor, RISHA (Rumah Instan Sederhana Sehat), a three-panel modular system that was refined into the current two-panel integrated RUSPIN model. Sustained commitment from stakeholders has enabled ongoing improvement and adaptation. A notable case study is the slum upgrading project in Uteunkot Village, Lhokseumawe City, Aceh Province, Indonesia [110], where the government provided prefabricated structural and non-structural components while encouraging homeowner and community participation in planning, implementation, and maintenance, reducing initial costs and promoting customization. The RUSPIN system complies with Indonesian Government Regulation No. 16/2021 and has undergone seismic resistance testing, confirming its suitability for disaster- and earthquake-prone regions [110].

The RPF system, developed in South Africa by Hennie Botes, initially faced skepticism but gained credibility after extensive testing and certification by the South African Bureau of Standards (SABS), Agrément South Africa, and the National Home Builders Registration Council (NHBRC). It received the 2006 Housing Innovation Award from the NHBRC and ABSA Bank. Since then, the system has expanded through partnerships with property developers and government-subsidized housing schemes for mass housing across Asia, Africa, and Latin America [104].

Both RUSPIN and RPF exemplify how long-term development, regulatory compliance, and strategic partnerships can drive trust, scalability, and sustained impact in affordable housing delivery.

6.5. Implications and Future Potential of RUSPIN and RPF Construction System

The RUSPIN and RPF systems represent a shift from reliance on imported foreign technologies toward localized and integrated construction approaches. RUSPIN’s focus on local material use, human-centered assembly, and integrated training makes it particularly suitable for environments with limited access to heavy machinery or imported components, effectively bridging traditional building practices with modern structural requirements. Although its standardized panel shapes may restrict architectural flexibility and initial material costs can be high without scaled local production, RUSPIN’s proven practicality and socio-economic benefits demonstrate its potential as a sustainable and scalable affordable housing solution across diverse developing regions.

Similarly, while the RPF system has been adopted in several countries, its future potential lies in its continued ability to produce durable, resilient homes using local materials and unskilled labor. The simplicity of its reusable formwork also positions it well for integration with emerging technologies, such as 3D-printed formwork and embedded sensors, to further enhance sustainability, quality, and construction efficiency.

6.6. Scalability and Technological Transfer of RUSPIN and RPF Method

The RUSPIN and RPF construction systems exemplify a shared commitment to scalability and technology transfer, though each pursues this goal through distinct approaches. RUSPIN’s scalability, while currently more localized, is grounded in its inherent adaptability. To achieve broader adoption, future efforts should focus on systematically exploring how the system can be customized for different contexts, considering variations in material availability (beyond concrete), labor skill levels, and structural requirements (such as those in non-seismic zones). The scalability of the RUSPIN model also depends on tailoring training programs to local labor markets and effectively navigating diverse regulatory frameworks.

In contrast, the scalability of the RPF system is propelled by its established international footprint, with distribution networks in over 26 countries and strategic collaborations with governments and developers. Its strength lies in its robustness, rapid construction capability, cost efficiency, and emphasis on local skill transfer, making it highly adaptable to a range of environments. To further advance its scalability, the RPF system would benefit from increased professional visibility through targeted media engagement, participation in conferences, and expanded academic and industry research to promote wider adoption.

7. Conclusions

7.1. Key Findings

This review systematically explored various cost-effective materials and innovative construction techniques for affordable housing in developing countries, addressing the research objectives outlined in Section 1.3. The analysis, including the RUSPIN and RPF case studies and critical success factors, underscores that affordability depends not only on selecting low-cost materials or advanced technologies but also on integrating local labor skills, available machinery, and training programs for local workers.

From our synthesis, wet construction, especially cast-in situ methods, suits developing countries with abundant low-cost labor but faces challenges of weak standards, long timelines, and high costs. Dry methods like sandbag and ISSB offer faster, low-skill, and sustainable options but struggle with limited urban acceptance and standards. Advanced systems such as precast concrete require higher investment, skilled labor, and policy support for broader adoption. Furthermore, carbon emissions were found to vary depending on the construction context and performance differences between wet and dry construction systems. Notably, these emissions can be significantly mitigated using supplementary cementitious materials (SCMs).

The RUSPIN and RPF case studies exemplify this crucial paradigm shift, demonstrating how modular monolithic plastic formwork, locally sourced materials, and community participation can overcome technical and financial barriers while enhancing seismic resilience. Integrating structural safety and disaster resilience within affordable housing not only safeguards communities but also minimizes the long-term environmental footprint associated with repeated reconstruction after natural disasters.

7.2. Contributions to Literature

This review makes a significant contribution to the existing literature by providing a structured, multi-country analysis that moves beyond a single-nation focus, offering a universal framework for affordable housing. Its broad scope enables the identification of significant, non-obvious insights that narrower studies cannot achieve. By applying the Critical Success Factors (CSFs) framework as an integrative bridge linking technical soundness to real-world application, its key contribution lies in the uniquely synthesized Materials–Methods–CSFs structure, which provides practical guidance for affordable housing implementation and demonstrates how non-technical factors, such as labor training, shape real-world scalability in developing regions.

7.3. Future Research Directions

• Material and technology Innovation

For construction materials commonly used in developed countries and gaining traction in some developing regions future research should identify bottlenecks hindering their broader adoption. This includes analyzing supply chain efficiencies, the structure of local construction industries, and regulatory frameworks. Conversely, for locally available materials and those derived from the secondary utilization of waste, continuous research is essential to optimize their application across diverse regional context, strengthen supply mechanisms, and improve structural reliability to ensure long-term durability and safety, including comprehensive lifecycle environmental impact assessments.

Future research should further investigate the long-term socio-economic impacts of these integrated approaches, assess their scalability across diverse climatic and cultural contexts, and explore how emerging digital technologies can be adapted to align with the unique constraints and opportunities in developing countries. A key consideration is understanding the socio-cultural acceptance and preferences related to innovative construction techniques to support their broader adoption. This includes prioritizing research and development into disaster-resilient designs and construction methods that minimize the need for costly and carbon-intensive reconstruction.

• Policy Implications

The structural strengthening and safety strategies synthesized in this review provide a technical foundation that construction professionals, policymakers, and governments can use to embed best practices into risk reduction and resilience-building efforts. This aligns with the Sendai Framework (2015–2030) and the World Bank–GFDRR Building Regulation for Resilience Programme. For policymakers, the identification of affordable yet highly resilient construction methods should inform future building code revisions. Priority should be given to developing accessible guidelines and training programs that translate complex technical findings into practical, on-the-ground building instructions, ensuring that new, safe construction methods are not only permitted but also correctly implemented by local builders.

• Recycled Materials for Insulation Applications

Although this review excluded studies focusing on thermal comfort, acoustic performance, and related insulation applications, it acknowledges the growing potential of textile waste and other recycled materials for producing thermal and acoustic insulation panels in affordable housing. Future research should examine the feasibility, cost-effectiveness, and sustainability of such materials in developing-country contexts, considering their availability, manufacturing processes, and compatibility with local construction practices. A dedicated investigation into these aspects would complement the findings of this review and expand the range of innovative solutions for affordable and sustainable housing.