Getting an honest insulation quote is tricky with all the different competing materials. Personally I can’t tell you how many jobs I’ve lost to a customer over a two thousand dollar difference when they weren’t getting even close to the same energy efficiency yield, thus costing them well over 10 thousand in heating/cooling costs inside the first ten years alone. This article will hopefully help enlighten some home builders and remodelers to some of the perils of combination systems, and how some contractors use this for personal gain at the customers’ expense.
First thing we see when we get a competing bid is that some contractors like to spray foam the customers’ walls and use fiberglass or blown-in cellulose in the attic. While this may sound like a good idea, it never is and there are a few reasons why. Most of your air intrusion in your conditioned space is actually coming from the bottom plate and the attic itself. When that air circulates in your house, it brings many dust/mold/mildew particles that are housed within the blown-in insulation.
This system is offered because while an R-27 of spray foam will drastically outperform (about 60-90 percent) an R-49 system of blown-in, the contractor will make the customer look at the R-value and think they’re getting a better deal. The contractor then usually inflates the price of blown-in a few thousand dollars so while it’s still cheaper than spray foam, the customer will walk away with an inferior product and the insulation company will be happy with an inflated profit margin. When in reality, any professional should know that if you had to pick between spray foam in your walls or attic, attic is a much better place for the spray foam to deaden the stack (or chimney) effect. It’s just much easier to fool customers with the attic space.