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Vapour diffusion and condensation control in high-performance buildings

Vapour diffusion and condensation control in high-performance buildings
Fall 2016 SABMag ConEd Article
GBCI: 0920010637

The article helps the reader to understand the correct selection and placement of vapour permeable and impermeable materials within the assemblies to increase durability, and improve the thermal and health performance of building envelopes by keeping the wall system dry throughout the service life of the building.

The article talks the reader through common wall construction assemblies such as stud cavity insulated walls, split insulated walls and highly insulated walls. It also teaches the reader the causes of and science behind vapour diffusion and condensation accumulation in walls.

Learning Outcomes
1. Understand the principles of vapour diffusion, and why this is an important factor to consider in wall assemblies.
2. Understand the proper and improper ways to address vapour diffusion in wall assemblies, particularly in cold climates.
3. Differentiate the various wall assembly construction methodologies and the benefits or impacts the assembly could have on condensation accumulation within various locations of the assemblies.
4. Understand all environmental factors both interior and exterior of the building that can impact vapour diffusion, air leakage and condensation accumulation through building envelopes.

All articles offered by SABMag are GBCI approved. To qualify for continuing education learning hours, practitioners must first read the technical article below, and then proceed to complete the short quiz at the end. You must receive 80% on the quiz to record the activity as part of your continuing education. An email will be sent to you and will act as your certificate of completion once you have successfully completed the requirements.

In order to obtain your CEU Certificate of Completion for this course (1h CE):

STEP 1 : Read the article Vapour diffusion and condensation control in high-performance buildings (PDF format)

STEP 2 : Take the quiz and get a minimum of 8 out of 10 correct answers to receive your Certificate of Completion.

Quiz by: Lorne Ricketts

This quiz was sponsored by METL SPAN CANADA


In which wall type is condensation accumulation due to air leakage of less concern?


In a split-insulated wall assembly, wall durability is increased and air leakage related condensation risk is reduced because the sheathing temperature is:


Vapour diffusion is the passage of vapour molecules through materials as a result of:


Latex paints, plywood, OSB and some foam plastic insulations are considered:


Vapour diffusion should be completely eliminated across a building envelope assembly.


What can potentially cause the most water to deposit in an assembly in a short amount of time?


Fungal growth can occur in wall assemblies if the Relative Humidity is not kept below:


For a material to be considered a “vapour barrier” it needs a US perm rating, or permeance value, of ___ or less.


When using vapour impermeable insulation outside the exterior sheathing, a vapour barrier is still needed on the interior, on the warm side of the insulation to stop vapour diffusion from interior to exterior.


The insulation materials mineral wool and fiberglass are considered:

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