It's a common misconception that a house can never have too much insulation. While it's true that many homes in the United States and Canada have inadequate insulation, it is possible to have too much. Installing insulation between ceiling joists is more difficult and expensive than insulating from the attic floor, so it's important to be aware of the diminishing returns of adding more insulation. If your attic already has an insulation rating of R-38, it may not be worth increasing it to R-60.
Investing in additional T-shaped uprights may not be as cost-effective as adding an extra inch of insulation throughout the entire space. Sealing and insulating the attic with spray foam is a great way to keep heat out and prevent moisture from entering. An energy auditor can help you determine if you have too much insulation in your house or if it is simply a poorly insulated attic. When insulating exterior walls from the outside, make sure to do it correctly.
The Building Code's insulation levels weren't determined by great minds pondering the “ideal” amount of insulation, but rather by a balance point where generating heat is better for the environment than buying and installing more insulation.