Consortium for Moisture Management for Exterior Wall Systems

Uncontrolled moisture accumulation in the building envelope reduces the structural integrity of its components through mechanical, chemical and biological degradation. Damage induced by moisture includes rotting of wood studs and other components, efflorescence and spalling of masonry systems, and rusting of wall fasteners. Also, excessive moisture in the envelope may affect the health of occupants directly and through the potential for breeding harmful organisms. From the user's point of view, buildings become "unfit-for-use" whether it is due to questionable structural integrity of the envelope or due to unhealthy indoor environment. In addition, moisture can also adversely affect non-health and safety performance factors such as the effectiveness of thermal insulation and aesthetic appearance.

NRC-IRC's unique Dynamic Wall Testing Facility (DWTF)

Effective moisture control in the building envelope is essential if acceptable service life is to be achieved for the built environment. Effective moisture control implies both minimizing moisture entry into the system, and maximizing the exit of moisture which does enter, so that no component in the system stays 'too wet' for 'too long'. But what is "too wet" and "too long"?  The project was planned  to answer these difficult questions

Objective

The objective of this project was to develop guidelines for moisture management strategies for wall systems to meet user requirements of long-term performance and durability for the wide range of climate zones across North America.

Scope

This project is about defining the ability of certain wall systems to manage moisture sources, including construction moisture, humid indoor and outdoor air, precipitation, and indoor human activities. Moisture may enter in many ways, including vapor diffusion, air movement, rain penetration, and seepage. The envelope design strategy must address all such processes, and must control moisture accumulation throughout the annual climatic cycle, over many years of service life. The focus will be on wood-frame buildings of 4 storeys or less, exposed to a range of outdoor climates found in North America (heating, cooling and mixed) starting with the warm and humid climate. Rain penetration control strategies was based on the rain-screen principle.

Activities

The research approach is three fold: field characterization of assemblies, laboratory experimentation on materials and components and mathematical modeling for prediction of long-term performance under many sets of conditions.

The project was broken down into the following eight tasks:

The final activity was to produce design guidelines on moisture management strategies. This was accomplished through the integration of all available information from the literature, experimental evaluation and modeling. This was a joint effort of the partners and NRC-IRC researchers. Research results within each task were documented and shared with the partners of the consortium. Technical research papers were presented at conferences and published in journals for public knowledge.

NRC-IRC Partners

• Canada Mortgage and Housing Corporation
• Canadian Fiberboard Manufacturers Association
• Canadian Plastics Industry Association
• Canadian Wood Council
• Dupont
• EIMA (External Insulation Manufacturers Association)
• Forintek Canada Corporation
• Fortifiber Corporation
• Louisiana-Pacific Corporation
• Marriott International
• Masonry Canada

Publications

An Integrated methodology to develop moisture management strategies for exterior wall systems
Kumaran, M.K.; Mukhopadhyaya, P.; Cornick, S.M.; Lacasse, M.A.; Rousseau, M.Z.; Maref, W.; Nofal, M.; Quirt, J.D.; Dalgliesh, W.A. 9th Canadian Conference on Building Science and Technology (Vancouver, B.C. 2003-02-27) pp. 45-62. 2003-02-01

Report from Task 2 of MEWS Project - Description of 17 Large Scale Wall Specimens Built for Water Entry Investigation in IRC Dynamic Wall Testing Facility
Bomberg, M.T.; Rousseau, M.Z.; Desmarais, G.; Nicholls, M.; Lacasse, M.A.
Research Report, NRC Institute for Research in Construction, 111,
pp. 141. 2002-10-01

Summary Report From Task 3 of MEWS Project at the Institute for Research in Construction - Hygrothermal Properties of Several Building Materials
Kumaran, M.K.; Lackey, J.C.; Normandin, N.; van Reenen, D.; Tariku, F. Research Report, NRC Institute for Research in Construction, 110, pp. 73. 2002-10-01

Report from Task 4 of MEWS Project - Task 4-Environmental Conditions Final Report
Cornick, S.M.; Dalgliesh, W.A.; Said, M.N.; Djebbar, R.; Tariku, F.; Kumaran, M.K.
Research Report, NRC Institute for Research in Construction, 113, pp. 110. 2002-10-01

Report from Task 6 of MEWS Project : Experimental Assessment of Water Penetration and Entry into Wood-Frame Wall Specimens - Final Report
Lacasse, M.A.; O'Connor, T.; Nunes, S.C.; Beaulieu, P.
Research Report, NRC Institute for Research in Construction, 133,
pp. 1 v. (various pagings) 2003-02-01

Benchmarking of IRC's Advanced Hygrothermal Model - hygIRC Using Mid- and Large-Scale Experiments
Maref, W.; Lacasse, M.A.; Booth, D.G. Research Report, NRC Institute for Research in Construction, 126, pp. 38. 2002-12-01

Final Report from Task 7 of MEWS Project at the Institute for Research in Construction : Long-Term Performance: Predict the Moisture Management Performance of Wall Systems as a Function of Climate, Material Properties, etc. Through Mathematical Modelling
Mukhopadhyaya, P.; Kumaran, M.K.; Tariku, F.; van Reenen, D. Research Report, NRC Institute for Research in Construction, 132, pp. 390. 2003-02-01

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
Beaulieu, P.; Bomberg, M.T.; Cornick, S.M.; Dalgliesh, W.A.; Desmarais, G.; Djebbar, R.; Kumaran, M.K.; Lacasse, M.A.; Lackey, J.C.; Maref, W.; Mukhopadhyaya, P.; Nofal, M.; Normandin, N.; Nicholls, M.; O'Connor, T.; Quirt, J.D.; Rousseau, M.Z.; Said, M.N.; Swinton, M.C.; Tariku, F.; van Reenen, D.
Research Report, NRC Institute for Research in Construction, 118, pp. 1 v. (various pagings) 2002-11-01

IRC studies on the control of rain penetration in exterior wood-frame walls
Lacasse, M.A. Solplan Review, (114) pp. 14-15. 2004-01-01

Executive Summary of Research Contributions Related to Moisture Management of Exterior Wall Systems (MEWS) - Modeling, Experiments, and Benchmarking
Maref, W Lacasse, M.A. Booth, D.G. Research Report, NRC Institute for Research in Construction, 127 pp. 15. 2002-12-01

Researchers study effects of climate and design on wetting and drying of walls
Rousseau, M.Z.
Construction Innovation, 8 (2), pp. 8-9. 2003-06-19 Construction Innovation, 7 (3) pp. 6. 2002-09-01

MEWS consortium methodology now available for use
Construction Innovation, 7 (2), pp. 1, 8. 2002-06-01

Application of hygrothermal modeling tool to assess moisture response of exterior walls
Mukhopadhyaya, P.; Kumaran, M.K.; Tariku, F.; Van Reenen, D.
Journal of Architectural Engineering, 12, (4), pp. 178-186. 2006-12-01

MEWS project produces long-term moisture response indicator
Mukhopadhyaya, P.
Construction Innovation, 8 (1), pp. 6-7. 2003-03-01

Results of IRC water penetration study will help industry tailor wall assemblies to climate
Lacasse, M.A.

Related Information

Institutes:

• NRC Institute for Research in Construction