Another benefit of using spray foam insulation in your home is reducing the stack effect that occurs naturally. Stack effect is essentially like a vacuum, when the heat rises in your home it pulls the air and the moisture in your home with it and is typically lost through your ceiling fixtures and interior walls which are areas that are not protected by plastic vapour barrier. When this happens that moisture can get trapped in your attic and cause mold issues and ice damning. When this process happens there is an equal amount of air being drawn in typically through your basement rim joists and windows thus creating the vacuum effect. One way of stopping stack effect is by removing the old insulation in your attic, applying a layer of spray foam insulation to create the air seal and vapour barrier and re-applying new blown cellulose insulation on top of the spray foam insulation and also by spray foam insulating the basement.