Mould Growth Risk for Internal Retrofit Insulation of Heritage-Protected Timber Plank Frame Walls
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe manuscript investigates the hygro-thermal consequences of adding interior insulation to heritage-protected Norwegian timber plank-frame walls. After laboratory determination of historic building-paper vapour resistance and WUFI 1-D simulations under coastal (Kristiansund) and inland (Hamar) climates, the authors conclude that (i) a 50 mm mineral-wool layer behind a polyethylene (PE) vapour barrier is generally safe, (ii) 100 mm may be safe when two exterior layers of highly permeable paper are present, and (iii) moisture-adaptive vapour barriers (MAVB) yield unacceptable mould risk in all tested scenarios. Energy-efficiency gains of 57–72 % are reported, while mould risk remains the primary constraint.
Major indications
- The study’s novelty and scope should be clarified. Open the introduction with a short, explicit comparison to earlier Norwegian retrofit research, showing exactly what knowledge gap this paper closes and why heritage practitioners should care.
- Please, strengthen the justification of key simulation assumptions. Explain why a sealed cavity (n = 0 h⁻¹) and a 70 % initial RH were chosen, and try to add a brief sensitivity check to show how mould-risk rankings shift if those values vary—readers need to trust that “safe” remains safe under plausible real-world conditions.
- I suggest to translate energy gains into actionable numbers. For example, it is possible to convert the reported U-value reductions into annual kWh m⁻² savings for a standard Norwegian climate; this lets practitioners balance moisture risk against concrete efficiency benefits instead of abstract percentages.
Minor comments
- Typos: “stucture” → “structure” (line 519) ; double spaces in several tables.
- Line 299 mixes “smart vapour barrier” and MAVB; define MAVB once and use consistently.
- Some in-text [ ? ] placeholders remain (e.g. 280-282). Replace with full citations.
- Revise Abstract sentence “One traditional Norwegian construction method, which was common …” for brevity.
Some typos are present in the text which are needed to be addressed
Author Response
Please see response given in attached file.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsManuscript ID: heritage-3710684
Title: Mould growth risk for internal retrofit insulation of heritage-protected timber plank frame walls
This study focuses on hygrothermal issues in traditional Norwegian timber-framed walls that are considered to have heritage value and potential for official designation. The authors effectively present the necessity of investigating hygrothermal performance under the assumption that such buildings are subject to legal constraints. To enhance the manuscript's clarity and value for Heritage readers, the following revisions are recommended;
- Figure 1 shows a typical timber-framed wall, but its link to heritage buildings is unclear. Please explain how it relates to traditional Norwegian heritage structures.
- To avoid confusion for readers, all references must be clearly cited. Please revise the instances where citations are marked with a “?”.
- In line 142, the term “windproof building paper” is used, while “building papers” appears in line 145. If these refer to the same material, the terminology should be unified for consistency and clarity.
- Page 5, “Exterior paper” and “Interior paper” are mentioned. Do these refer to the outer and inner papers in Figure 6? Please clarify their meaning in the text.
- In Table 2, I3, I4, and I5 differ only by manufacturing year, and their thickness values in Table 3 are similar. However, the noticeable variation in sd values raises the question of whether there are differences in material composition. This point should be discussed in the manuscript.
- Cases 1–21 are introduced for the first time in the Results section. The rationale behind defining these cases, as well as the differences among them, should be clearly described in Section 2: Materials and Methods.
After confirming the major revision opinion, please revise the paper including the above information.
Author Response
Please see response given in attached file
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThis study mainly aims to explore the hygrothermal challenges of retrofitting internal insulation on heritage-worthy timber plank frame walls, by addressing 3 questions. it is an add valued research help to control vapor transmission into buildings, as energy efficiency focused activity.
The main comments are
-methodology, particularly for calculation of sd value need to be more clear.
-please identify WUFI (line 12) and sd value (line 14).
-limes 76, 104, 128 (?) what do you mean, (i.e. nonidentified reference or what).
-section of fungi growth is opaque for me, as fungi can grow under 50% RH%, however above 80% the fungal taxa only may be changed to more tertiary fungal colonizers. Please more details and interpretation on this point.
-Is there any change of sd value with changeable temperature and RH% , as similar of real environment, please take this point in account during discussion.
-conclusion should be reformulated to the main results in the study.
Comments on the Quality of English LanguageNo -comment
Author Response
Please see response given in attached file
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsSuggested comments have been correctly implemented in the revised manuscript.
Reviewer 2 Report
Comments and Suggestions for AuthorsManuscript ID: heritage-3710684
Title: Mould growth risk for internal retrofit insulation of heritage-protected timber plank frame walls
I have submitted six revision comments for publication in Heritage. I have confirmed that all comments have been reflected in the revised manuscript shared via email. I hereby submit my opinion on the acceptance of the paper to this journal.
