One of the dramatic failings in our building envelope is the thermal control layer. I have written before about the thermal layer and its place in the building envelope control layers, (Click here to learn about the Water, Air, Vapour & Thermal layers).
Despite thermal insulation being at the forefront of peoples minds when it comes to energy efficiency, we do a particularly bad job of implementing this component.
Would it surprise you to learn that not all of your walls are insulated? I’m not talking about thermal bridging through the frame or the thermal weakness of windows, I’m talking about substantial areas of the wall that are just NOT insulated.
These uninsulated wall areas are:
- External corners
- Intersection of internal wall to external wall.
- Header lintels over windows & external doors.
I have provided images indicating the location of these areas. In total, for the illustrated house, we have 8 square meters of potentially uninsulated wall area due to these external pockets and lintel locations. That’s 8% of the wall area.
So why does this happen? In the case of external wall pockets (1 & 2 highlighted in yellow) the sequence of events is for the wall wrap to be installed to make the building weather tight before insulation is installed. The external pockets are therefore covered prior to the insulation contractor turning up, rendering them inaccessible. There are ways to overcome this problem, the simplest way being to instruct the builder to insulated the pockets at the time of installing the wall wrap.
What about the header lintels? These are generally not insulated because the lintel encroaches into the wall cavity rendering the insulation batts too thick to fit. ( 3 highlighted in pink on the floor plan). In this case the batt just needs to be split to fit in the available space.
LESSON: Don’t assume that the entire wall area is going to be insulated. Before you begin your build, have a talk to the builder about ensuring that these neglected areas of wall are attended to.