The rim joist is an area often overlooked when it comes to home insulation, and it is also a huge source of energy loss. When the rim joist lacks proper insulation and air sealing, heat is lost by conductive transfer to the outside, and cold air infiltrates the basement through joints and other gaps drilled on the sill plate for plumbing, electricity and fuel lines. Our team used polyurethane expanding foam to stop air leaks in the rim joists.