Adding insulation to existing exterior walls has the potential to create moisture related problems as moisture from indoor gets into moderately leaky building envelopes. A test was designed to investigate the behaviour of exterior walls with and without added insulation and having different leakage characteristics.

Nine wall assemblies, included within a full-scale test hut, were subjected consecutively to winter and late spring weather conditions. All specimens had glass fiber batt insulation between the studs. In three of the specimens, extruded polystyrene board were added on the cold side of the assembly, and in two specimens insulation was added on the warm side. These three compositions were studied with various air leakage paths: a long path, a concentrated path, and a uniformly distributed exfiltration path.

Moisture content in the fiberboard sheathing and wood studs measured throughout the test are compared to demonstrate the influence of location of insulation and geometry of air leakage. The results show that walls having the same R-value but a different composition do not necessarily behave the same way. Depending on the position of the added insulation and its properties, the sensitivity to air leakage will vary. It is also shown that air leakage should be taken into account before increasing the thermal resistance of existing exterior walls.

• insulation
• rain penetration, water intrusion

1. Building Physics: 3rd International Conference in Building Physics
2. Building pressurisation can affect possibility of mould growth
3. Comparaison de m¨¦thodes de mesure de flux de chaleur pour sp¨¦cimens de grandes et moyennes dimensions
4. Experimental setup for the study of air leakage patterns
5. Final Report from Task 8 of MEWS Project (T8-03) - Hygrothermal Response of Exterior Wall Systems to Climate Loading: Methodology and Interpretation of Results for Stucco, EIFS, Masonry and Siding Clad Wood-Frame Walls
6. Impact of added insulation on air leakage patterns
7. Impact of added insulation on the hygrothermal performance of leaky exterior wall assemblies
8. Impact of air leakage pattern on reinsulated walls
9. Mapping of air leakage in exterior wall assemblies
10. Report from Task 2 of MEWS Project - Description of 17 Large Sale Wall Specimens Built for Water Entry Investigation in IRC Dynamic Wall Testing Facility
11. Report from Task 8 of MEWS Project - MEWS Methodology for Developing Moisture Management Strategies - Application to Stucco Clad Wood-Frame Walls in North America
12. Study of the reduced impact of thermal bridges in two sprayed-applied polyurethane wall assemblies  

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. Rainwater runoff from building facades: A review
16. Rapport Final Projet Site Internet - L'enveloppe du batiment et l'efficacit¨¦ ¨¦nerg¨¦tique
17. Review and framework for large-scale laboratory studies on wetting and drying of building envelopes
18. Study of the reduced impact of thermal bridges in two sprayed-applied polyurethane wall assemblies
19. Testing of flat roofs insulated with cellulose fiber
20. The impact of sorption history and hysteresis on moisture pattern in a wood-framed building envelope
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  

1. A limit state design (LSD) approach for comparing relative drying performance of wood-frame envelope systems with full-scale lab, A roadmap towards intelligent net zero- and positive-energy buildings,
2. A new test method to determine the relative drying capacity of building envelope panels of various configurations
3. A new testing method to evaluate the relative drying performance of different building envelope systems using water trays
4. A quantitative study for the measurement of driving rain exposure in the Montr¨¦al region
5. A review of research activities in energy efficiency in buildings in Canada
6. Airtightness testing and air flow modeling of two and three-unit multifamily buildings
7. Airtightness testing of two- and three-unit buildings with a single fan
8. Approach for the simulation of wetting due to rain infiltration for building envelope testing
9. Approach for urban driving rain index by using climatological data recorded at suburban meteorological station
10. Behavior of wall assemblies with different wood sheathings wetted by simulated rain penetration
11. Building Physics: 3rd International Conference in Building Physics
12. Building pressurisation can affect possibility of mould growth
13. Cavity pressure in rain screen walls
14. Comparaison de m¨¦thodes de mesure de flux de chaleur pour sp¨¦cimens de grandes et moyennes dimensions
15. Continuous folded plate structures under uniform load
16. Creative case adaptation for building engineering design
17. Design and construction of an environmental chamber facility
18. Design Methodology of Solar Neighborhoods
19. Development of experimental procedure to evaluate potential movement of mold spores from wall cavity to indoor environment
20. Development of HAM tool for building envelope analysis
21. Effect of capillarity on rainwater penetration in the building envelope
22. Environmental chamber for investigation of building envelope performance
23. Essai sur les toits plats isol¨¦s ¨¤ la fibre de cellulose
24. Evaluation of radiance's genBSDF capability to assess solar bidirectional properties of complex fenestration systems
25. Experimental evaluation of potential transport of mold spores from moldy studs in full-size wall assemblies
26. Experimental setup for the study of air leakage patterns
27. Experimental study of temperature distributions across two curtain wall systems
28. Folded sandwich plate structures
29. Identification and transport investigation of microbial volatile organic compounds in full-scale stud cavities
30. IFC-based framework for evaluating total performance of building envelopes
31. Impact of added insulation on air leakage patterns
32. Impact of air leakage pattern on reinsulated walls
33. In-cavity evaporation allowance--A drying capacity indicator for wood-frame wall system
34. Influence of air space on multi-layered material water vapor permeability measurement
35. Influence of facade geometry on weathering
36. Integrated analysis of whole building heat, air and moisture transfer
37. Interzonal air and moisture transport through large horizontal openings in a full-scale two-story test hut: Part 1 - Experimental study
38. Interzonal air and moisture transport through large horizontal openings in a full-scale two-story test-hut: Part 2- CFD study
39. Large scale testing of two flat roof assemblies insulated with cellulose
40. Mapping of air leakage in exterior wall assemblies
41. Measuring air leakage characteristics with flexible double air chambers
42. Measuring air leakage of full-scale curtain wall sections using a non-rigid air-chamber method
43. Methods for the assessment of moisture content of envelope assemblies
44. Modeling of moisture behavior of wood planks in nonvented flat roofs
45. Modelling of indoor air humidity: the dynamic behaviour within an enclosure
46. Moisture buffering capacities of five North American building materials
47. Nonlinear elastic analysis of panelized shear sandwich walls
48. Numerical investigation of the influence of room factors on HAM transport in a full-scale experimental room
49. Performance evaluation protocol for full-scale wood-frame building envelopes
50. Potential of rain screen walls to prevent rain penetration: pressurized cavity principle
51. Quantitative driving rain exposure on a vertical wall at various Canadian cities
52. Rapport Final Projet Site Internet - L'enveloppe du batiment et l'efficacit¨¦ ¨¦nerg¨¦tique
53. Review and framework for large-scale laboratory studies on wetting and drying of building envelopes
54. Study of the reduced impact of thermal bridges in two sprayed-applied polyurethane wall assemblies
55. Study on thermal performance of curtain walls using infrared thermography
56. Test method to measure the relative capacity of wall panels to evacuate moisture from their stud cavity
57. Testing of flat roofs insulated with cellulose fiber
58. The dynamic modelling of air humidity behaviour in a multi-zone space
59. Transfer of heat, moisture and air through metal curtain walls
60. Transient model for coupled heat, air and moisture transfer through multilayered porous media
61. Use of an environmental chamber to investigate large-scale envelope specimen hygrothermal performance