Above Grade Walls

2x4 wood framed wall with rigid exterior insulation

Exterior walls built with 2x4 framing were the typical method of constructing residential homes for many years. The switch to 2x6 wall framing was made not because 2x4s were structurally inadequate but solely to allow for additional room in the wall thickness to install greater insulation values.

R-2000 Homes have been built in Manitoba with 2x4 wall framing, R-12 fiberglass insulation and exterior insulation sheathing and are performing well. HOT2000 computer modeling suggests that these walls slightly outperform standard 2x6 wall construction with R-20 fiberglass insulation. The rigid insulation eliminates the effects Thermal Bridging in the 2x4 wall framing that are common in 2x6 construction.

There are many different types and thicknesses of rigid insulation sheathing boards available in the marketplace. Each has its own advantages in performance and cost. A HOT2000 analysis of your home will help you decide exactly which product is best for your wall design.

Advantages of using 2x4 exterior wall framing with rigid exterior insulation over standard 2x6 construction:

• performance equal to or slightly exceeding 2x6 R-20 construction
• depending on local prices, may be less costly to build
• only minor changes required to standard construction practices
• structural plywood or OSB wall sheathing can be eliminated in favour of diagonal wall bracing
• easier detailing of continuity of the air/vapour barrier at floor headers
• reduced risk of moisture and mould accumulations within the wall
• nail pops and drywall cracks may be reduced as the wood framing is kept warmer