Risk of Moisture in Diffusionally Open Roofs with Cross-Laminated Timber for Northern Coastal Climates
Abstract
:1. Introduction
2. Materials and Methods
2.1. Model in WUFI®Plus
2.2. Bounduary Conditions and Assumptions
2.2.1. External Climate
2.2.2. Internal Climate
2.2.3. Initial Moisture Content in Wooden Elements
2.2.4. Air Change Rate
2.2.5. Substrate Class for Mold Growth Prediction
3. Results and Discussion
3.1. Impact of Initial Moisture Content
3.2. Impact of Increase in Air Change Rate in Ventilated Cavities
3.3. Risk of Condensation
3.4. Mold Growth
3.5. Model Accuracy
4. Conclusions
- No risk of CLT layer moisture was noted (for any calculation variants).
- In the case of OSB for the two coldest climates at low ACH and at internal RH over 50% moisture content exceeded critical values. According to the authors, for rooms with a relative humidity exceeding 50%, the use of diffusionally open structures is not advisable. Nevertheless, it is possible to use more moisture-resistant OSB4 instead of OSB3 or to increase the area of inlet openings for ventilated spaces, so that in all weather conditions the ACH exceeds 15 h−1 (this solution requires calculations as to whether it is possible to increase the ventilated space for structural reasons). As a last resort, the partition can be sealed with a vapor barrier.
- Increasing the ACH above 15 h−1 caused the MC to fall below the critical value. Further increase in ACH (up to 40 h−1) caused a further decrease in recorded MC values. Above 40 h−1 no more changes were noted.
- It is critical to control the moisture content of wood delivered to the construction site and to avoid its moisture during construction. Increasing the initial moisture content of wooden elements to the maximum permissible for coastal climates resulted in a significant increase in MC above the permissible values.
- For subpolar/subarctic climates with an initial moisture content of wooden construction elements of 10%, the predicted mold growth exceeds 100 mm · year−1. This indicates necessity of additional criteria or further investigations are needed for assessing acceptability. MI = 1.5–2.25 allows to state that there is a moderate risk of mold growth. Increasing the initial MC for these climates may result in an increased risk of mold growth above an acceptable value (>300 mm · year−1).
Author Contributions
Funding
Conflicts of Interest
References
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Indoor Air Relative Humidity Scenarios | Climates | |||
---|---|---|---|---|
Greenland | Iceland | Scotland | Norway | |
(A) | (B) | (C) | (D) | |
Free floating (I) | AI | BI | CI | DI |
RHmin = 40% (II) | AII | BII | CII | DII |
RHmin = 50% (III) | AIII | BIII | CIII | DIII |
RHmin = 60% (IV) | AIV | BIV | CIV | DIV |
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Sadłowska-Sałęga, A.; Wąs, K. Risk of Moisture in Diffusionally Open Roofs with Cross-Laminated Timber for Northern Coastal Climates. Buildings 2020, 10, 10. https://doi.org/10.3390/buildings10010010
Sadłowska-Sałęga A, Wąs K. Risk of Moisture in Diffusionally Open Roofs with Cross-Laminated Timber for Northern Coastal Climates. Buildings. 2020; 10(1):10. https://doi.org/10.3390/buildings10010010
Chicago/Turabian StyleSadłowska-Sałęga, Agnieszka, and Krzysztof Wąs. 2020. "Risk of Moisture in Diffusionally Open Roofs with Cross-Laminated Timber for Northern Coastal Climates" Buildings 10, no. 1: 10. https://doi.org/10.3390/buildings10010010
APA StyleSadłowska-Sałęga, A., & Wąs, K. (2020). Risk of Moisture in Diffusionally Open Roofs with Cross-Laminated Timber for Northern Coastal Climates. Buildings, 10(1), 10. https://doi.org/10.3390/buildings10010010