Can You Put Insulation on the Outside of the Mud Sill?

Importance

• The Environmental Protection Agency at EPA.gov advises that placing insulation on exterior walls will keep the wall's temperature and moisture content steady throughout the year. Insulation also slows down heat transfer through your walls, allowing the temperature inside your home to remain comfortable. Insulation is most efficient when moisture controls are in place and all air leaks are sealed.

Placement

• The EPA recommends placing insulation between the top of the foundation wall and the mud sill and between the mud sill and the rim joist of your home. Also place insulation between the rim joist and subfloor. You can add insulation to interior walls as well. Many types of insulation have membranes or coatings that act as a vapor barrier, keeping moisture from damaging your home.

Moisture Control

• To get the most benefit from your insulation, you must keep moisture from seeping into your home through foundation walls. Seal any gaps with caulk or foam board insulation panels. Be sure the lot your home is built on is graded in a way that directs water away from your home. Improper grading can allow surface water in your yard to run into your home and cause moisture damage and mold growth. Keep all downspouts and gutters free from debris, and be sure your downspouts carry water at least 3 feet from your home.

Air Sealing

• When outdoor air seeps into your home, the insulation placed on the outside of the mud sill is less effective. According to the United States Department of Energy, sealing air leaks reduces energy costs, improves the durability of your home and creates a healthier living environment. Seal any cracks in your foundation with caulk to keep your home as efficient as possible.