Above Grade Wals

Double wall construction

These expanded wall systems were developed to accommodate very high levels of insulation, to ensure that the air/vapour barrier would not be penetrated by electrical or plumbing systems and to eliminate the thermal bridging effect of the wood framing.

Double wall framing consists of a load bearing interior wall and a lighter framed exterior wall that supports the exterior finishes. The thickness of the assembly can be expanded to adjust for higher insulation values. Because of its higher insulation values, very often the location of the air/vapour barrier can pushed back into the wall assembly from the more typical installation on the room side of the insulation. This allows for electrical wiring and receptacle boxes to be installed completely on the interior side of the air/vapour barrier and avoids all the normal associated air sealing activities of those penetrations.

The general use of this type of wall system is not as common as it once was in Manitoba due to its potential for higher material and labour costs and the multitude of other high performance wall systems available.

A number of R-2000 double wall homes continue to be successfully built in Manitoba. Their energy performance is exceptional, with electrical heating consumption, in some cases, coming close to the electric hot water tank energy consumption.

In addition to standard double wall framing, a system made popular by one Manitoba Licensed R-2000 Builder is that of the truss wall design. The trusses for the wall are premanufactured in the builder's shop and brought to site to be assembled in a similar fashion to single wall wood framing.

Advantages of double wall construction:

• smaller dimensional lumber can be used
• allows for a wide range of higher insulation values
• thermal bridging is eliminated through the wood framing
• easy to maintain a good air/vapour barrier