ENBIX Wall Library - Business as Usual - Tier 1 2x6 Exterior

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This assembly is one of the most common methods of constructing residential buildings in Canada at the time of this report. AEF requested that a “Business as Usual” assembly be developed to display a code requirement level of construction. GBTAC staff, with assistance from AEF, developed the design for this assembly utilizing feedback from the residential building and construction professionals. The wall assembly, from exterior to interior, contains:

Exterior Cladding
WRB, vapour open
Structural sheathing
2x6 stud wall @ 24” O.C. with fibreglass batt cavity insulation
Airtight 6 mil polyethylene sheet vapour barrier
1⁄2” gypsum board
Interior finish

Construction of this assembly mockup was very straightforward and easy to complete. This being a very common assembly, most home builders and trades people will have constructed or worked with this assembly before.
The air control layer for this assembly is the 6-mil poly VB. Maintaining a continuous air control layer was achieved with this membrane along with the following materials:

Compressed acoustical sealant at joints and openings of the VB and under the wall bottom plates.
Airtight electrical boxes with gasket seals at the face.
Expanding spray foam insulation and tape around mechanical penetrations.
Foam backer rod and caulking at the windows.

Assembly Advantages

Easy to build and common across Canada.
Materials were easily accessible at most hardware or building supply stores.
Materials selected were more affordable compared to other high-performance materials in the other assemblies.
Construction did not require specialized professionals outside the norm to design or build.
The VB being the air control layer on the interior of the assembly means that installers have a flat floor and an interior environment for the installation of this layer.

Assembly Disadvantages

Airtightness detailing was challenging as the air control layer is on the interior of the wall resulting in breaks in the continuity at floor, partition, electrical boxes, and mechanical junctions that needed to be detailed.
Acoustical sealant as the air seal can be very messy and if not installed with care, can get on and damage certain finishes.
If acoustical sealant is not properly installed and compressed then the
effectiveness of it can be greatly reduced.
Once the walls are lifted, it was not possible to see if the air control layer is continuous under the wall plate to the floor sheathing, unless a membrane is installed under the plate extending to the interior.
There is a considerable amount of structural wood thermal bridges in this
construction method. This causes heat loss, resulting in higher energy use.

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