This is the last segment in our series on common issues with exterior wall cladding.
Sometimes we find a large number of patched holes on exterior wall surfaces. If these are in a uniform pattern, they often indicate insulation blown into the wall. This insulation can include cellulose and controversial materials such as urea formaldehyde foam insulation. Adding insulation to a wall is a bit more difficult than adding it to an attic because, in a wall, the insulation is hidden between the interior and exterior wall coverings. Removing the wall covering to insulate the wall cavity just isn’t cost effective. It’s cheaper and easier to create small penetrations in the wall so that the insulation can be blown in.
Adding insulation through building exteriors is a retrofit to reduce energy costs and improve house comfort. This approach is usually taken when no interior renovations are planned but insulation improvements are considered a priority.
Adding insulation from the outside creates a number of holes in the exterior siding that may not be well patched. In some cases, the patches are very visible. In other cases, they are patched so well they are completely invisible. Poor patches may be water entry points. Insulation in old walls can reduce temperatures in wall assemblies and result in condensation problems where none had existed before. The insulation makes the wall cavity colder. Since insulation is often added without providing an air/vapor barrier, there is a higher risk of the warm, moist air that leaks through the walls condensing within the wall system.