ABSTRACT

Moisture present in envelope assemblies can accumulate within hygroscopic materials such as wood and cellulose insulation. The amount of moisture adsorbed by the material is dependent on the relative humidity of air to which it is exposed or to the availability of water. These relationships are available under the form of sorption curves. It is known that wood does not retain the same quantity of moisture content when exposed to the same relative humidity of the ambient air, whether wood is getting drier or wetter. This phenomenon, called hysteresis between the adsorption and desorption curves, is rarely considered during modeling or experimental studies of the building envelope. Because of hysteresis, the prior conditions of moisture exposure of wood have an impact on its performance under the next set of conditions. Therefore, the sorption history of wood should be taken into account in the assessment of the moisture performance of envelope assemblies. This paper reviews the concepts mentioned above and then presents experimental data that exhibit the impact of different sorption histories on the moisture pattern of wood members in assemblies exposed to the same conditions. It is shown that the final moisture content depends on the sorption history.

• HAM: theory and modelling : hysteresis in sorption isotherm
• wood frame houses and walls, wood structure

1. Approach for the simulation of wetting due to rain infiltration for building envelope testing
2. Behavior of wall assemblies with different wood sheathings wetted by simulated rain penetration
3. Comparaison de m¨¦thodes de mesure de flux de chaleur pour sp¨¦cimens de grandes et moyennes dimensions
4. Essai sur les toits plats isol¨¦s ¨¤ la fibre de cellulose
5. Experimental setup for the study of air leakage patterns
6. Hygroscopic behavior of paper and books
7. Impact of added insulation on air leakage patterns
8. Impact of air leakage pattern on reinsulated walls
9. Large scale testing of two flat roof assemblies insulated with cellulose
10. Mapping of air leakage in exterior wall assemblies
11. Methodology and Application of Simulated Wind-Driven Rain Infiltration in Building Envelope Experimental Testing
12. Methods for the assessment of moisture content of envelope assemblies
13. Modeling of moisture behavior of wood planks in nonvented flat roofs
14. Moisture occurrence in roof assemblies containing moisture storing insulation and its impact on the durability of building envelope
15. Moisture performance of leaky exterior walls with added insulation
16. Rainwater runoff from building facades: A review
17. Rapport Final Projet Site Internet - L'enveloppe du batiment et l'efficacit¨¦ ¨¦nerg¨¦tique
18. Review and framework for large-scale laboratory studies on wetting and drying of building envelopes
19. Study of the reduced impact of thermal bridges in two sprayed-applied polyurethane wall assemblies
20. Testing of flat roofs insulated with cellulose fiber
21. The need for an integrated computer-based tool to support building envelope design
22. Use of an environmental chamber to investigate large-scale envelope specimen hygrothermal performance