Best Practices for Insulating Slabs & Footings
By Stephen Magneron, CPHC, Advanced Housing Specialist
Insulation under the slab is one of the most overlooked strategies in most homes built today. Not only does it help create a warm, dry, comfortable basement, but it will also save on heating bills.
Slabs can be from 10% to 30% of the heat loss surface area of a home, with townhomes on the lower end to sprawling bungalows on the higher end. Admittedly, the heat loss is less than that of the roof or the above grade walls that experience higher temperature difference between the indoors and outdoors. However, the ground’s constant temperature is around 10oC in the Ottawa area. Imagine if the temperature outside was 10oC all year round, 24/7, and your house was uninsulated. You would be either very uncomfortable or paying 24/7 to keep the indoor temperature at a cozy 20oC. It truly makes little sense that we’ve been upgrading all our other thermal assemblies yet commonly leave such a large portion of our building envelope completely uninsulated!