Materials and Equipment
- Expanding spray foam
- Caulk and caulk gun
- Old clothes
- Box cutters
- Safety glasses, gloves and dust mask/protective face mask
Tips and Safety Considerations
- Gather all your tools and supplies before you begin to minimize trips into and out of your basement or crawlspace.
- Be sure that the work area is well lit. Use a drop light for most of the space if necessary and keep a flashlight or headlight handy.
- During cold weather, try to pick a temperate day and wear warm clothes.
Addressing Indoor Air Quality
Sealing the home can trap indoor air pollutants such as carbon monoxide, radon and volatile organic compounds (VOCs) and create unsafe conditions. Properly addressing this may require additional ventilation fans to maintain safe air quality in your home and repairs to reduce or eliminate the sources of indoor air pollutants. Here are some things to consider before starting your home sealing project:
If you are in a high radon area, consider contacting a contractor to conduct a radon test and install radon mitigation systems before sealing your home. Find out more at EPA's Consumer Guide to Radon Reduction.
If you have an appliance that uses oil or gas, consider hiring a Home Performance Contractor to test those appliances to ensure they are properly drafting combustion gasses before and after sealing your home. Sealing in some cases can cause naturally venting combustion appliances to backdraft gases back into your home, creating unsafe conditions.
Sealing your home can trap indoor air pollutants. To properly address this may require additional mechanical ventilation to maintain safe air quality in your home.
For more information on safe ventilation methods, visit EPA's Indoor Air Quality for Homes Page.
Sealing Your Basement or Crawlspace
Look for common locations of air leaks in basements and crawlspaces:
- Between rim joists and under the sill plate
- Around windows
- At wiring holes
- Around plumbing pipes
- Around the door to crawlspace, if attached to outside of house
- Around foundation at the sill plate, if not sealed properly
Step 1. Seal any gaps or cracks in basement wall, ceiling or floor. It is best to seal up the top and bottom of the inside of the rim joist cavity. This is especially important at areas such as bay windows that hang off the foundation. Use caulk for any gaps or cracks ¼ inch or less and spray foam for anything larger. It is also very important to seal any holes for wires, pipes or other service areas that may lead to other floors of your home.
Step 2. Cut insulation and insert accordingly. Insert and secure all insulation between holes in rim joists. If using batts, cut the insulation to fit and place against the rim joist. If using rigid foam insulation, foam around the edges to hold the insulation in place. After installing the rigid foam insulation or fitting batts into rim joists, seal any remaining holes and cracks to make your basement airtight.