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Desired Outcome:
Desired Outcome:
Air and thermal boundaries will be aligned, and all accessible penetrations in the basements or crawl spaces, between the outside, will be permanently sealed to prevent air and moisture penetration. This section applies to closed basements and crawl spaces in which the thermal boundary of the home is the foundation walls rather than the sub-floor.
Air and thermal boundaries will be aligned, and all accessible penetrations in the basements or crawl spaces, between the outside, will be permanently sealed to prevent air and moisture penetration. This section applies to closed basements and crawl spaces in which the thermal boundary of the home is the foundation walls rather than the sub-floor.
Before
Before
Unsealed basement wall & sill
After
After
Sealed basement wall & sill
Steps
Steps
- Remove existing insulation
Remove all insulation from sill box area.
Remove or adjust wall insulation to allow access to cracks, joints and penetrations
2. Surface Prep
2. Surface Prep
Sweep or vacuum all surfaces where sealants will be applied to remove dust and debris and allow for maximum adhesion
3. Seal penetrations
3. Seal penetrations
Penetrations will be sealed with safe, durable, effective materials.
Sealant must be compatible with their intended surfaces, allow for differential expansion and contraction between dissimilar materials, and meet any applicable building codes.
4. Pest exclusion
4. Pest exclusion
If penetration is greater than ¼ inches, caulking, steel wool, or other pest-proof material will be used to fill the penetration before sealing to prevent pest entry
5. Air seal at floor
5. Air seal at floor
Air seal the joint between the basement floor and the basement wall wherever accessible using a flexible masonry sealant such as Sikaflex™.
6. Air seal walls
6. Air seal walls
Air seal joints, cracks, and penetrations in basement or crawl walls using a flexible masonry sealant for vertical surfaces.
7. Seal Gaps in masonry foundations
7. Seal Gaps in masonry foundations
Use mortar or vertical masonry sealant to seal cracks and gaps in brick, stone or rubble foundations.
Gaps can be sealed on either the interior or exterior side of foundation.
DO NOT cover up weep holes or brick veneer vents.
8. Seal off vents & access points
8. Seal off vents & access points
Vent openings and access points leading to the exterior will be permanently closed and sealed to prevent air and moisture penetration.
Secure rigid air-tight materials over openings, and use mastic, caulks, or foam to complete air sealing.
Materials that will be exposed to the exterior must be durable materials. Foam plastics cannot be exposed to the exterior or UV rays.
8a. Complete air sealing
8a. Complete air sealing
Use mastic, caulk or foam to complete air sealing.
9. Air seal sill box
9. Air seal sill box
Air seal Joints, cracks, and penetrations in Sill box area using caulk, mastic, 1-part foam, or 2-part foam.
10. Air seal around windows
10. Air seal around windows
Seal gap between window and basement wall using acrylic or silicone caulk
11. Air seal crawl space access
11. Air seal crawl space access
Follow the steps in Attic Access to seal the Crawl Space access
12. Reinstall existing insulation
12. Reinstall existing insulation
Reinstall any insulation that was removed or adjusted prior to air sealing unless work order calls for installation of new insulation
13. Photograph work
13. Photograph work
Take photos of all work that is not easily accessible or that will be covered
14. Worst Case Draft Test
14. Worst Case Draft Test
Conduct a Worst Case Draft Test to verify Category I, II and III appliances are venting safely before leaving home for the day.
Testing shall be recorded using the WAP Worst Case Draft Test from.
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