In the framing of a building, a rim joist is the final joist that caps the end of the row. These components support your floors and ceilings. A rim joist makes up the end of the box that comprises the floor system.
In the basement, the rim joist is often an overlooked area when it comes to heat loss. Evidence of air gaps can often be embodied by spider webs, critter droppings, green vines growing in the foundation or opened tops of block walls. Any cold air blowing into the basement pushes the home’s heated air out.
In the past, fiberglass batting worked well as rim joist insulations. Now, a two-part urethane spray foam not only insulates better, but also seals all cracks and crevices. This material will even address the tops of cinder block walls!