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Technical Corner

Above Grade Walls

2x6 framed walls with exterior rigid insulation

For homes heated with electricity, homes in northern Manitoba and for those progressive homeowners who consider payback costs over the life of their new home, adding rigid insulation to the exterior walls, can be a very cost effective option.

In northern Manitoba, the minimum R-value required by the Manitoba Building Code for an exterior wall is R-26 — which necessitates the use of rigid insulation on most new homes built in that area.

rigid insulation graphicBy wrapping your home with exterior rigid insulation, heat loss through the wood framing is significantly reduced (see Effects of Thermal Bridging in Wood Frame Walls) and overall R-values increase anywhere from 20 to 30 per cent. The effect of this improvement is more pronounced in two story homes where the exposed surface area of the walls increases over a single story bungalow design.

Advantages of using exterior rigid insulation on 2x6 wall framing:

  • reduced heat loss and lower energy bills
  • 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

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.

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