How to Insulate a Basement Wall on the Outside

When it comes to heating and cooling costs, every little bit helps. Reducing the amount of heat lost through your basement can help you maintain consistent heat in your home through the winter. If you use your basement, this is particularly important. It's also important to keep moisture from building up in the basement, something that insulation and a vapor barrier can help achieve.

Shovel
Waterproofing material
Paint sprayer
Spray foam insulation
Caulk
Tape measure
Foam board insulation
Foam adhesive
Foil tape
Plastic sheeting
Staples and staple gun

Instructions

- 1
  Remove any siding over your basement walls. Save for reinstallation once you are done with insulating.
- 2
  Dig a trench at least 2 feet wide and 2 feet deep with a shovel where the wall meets the ground.
- 3
  Look over the exterior basement walls for cracks, fissures or moisture. If moisture is found, apply exterior waterproofing material with a paint sprayer. These are usually clay or rubber-based and will protect your basement walls. Fill in cracks or fissures with spray foam insulation or caulk.
- 4
  Measure the height and length of the walls. Multiply the measurements to get the square footage.
- 5
  Apply foam board insulation rated for exterior walls to your basement walls. Cut the foam boards to fit with a utility knife and cover enough area for one sheet at a time with an adhesive made for the foam.
- 6
  Tape seams with foil tape. Cover the foam insulation with a vapor barrier such as plastic sheeting. Hold the sheeting in place over the insulation and staple with a staple gun to secure. Alternatively, you can coat the foam with a rubberized waterproofing product compatible with the insulation. Apply with a paint sprayer or brush.
- 7
  Fill in your trench, allowing the soil to slope away from the foundation walls and replace your siding.

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