Professional energy auditors consistently find air leakage in predictable locations. Understanding these common problem areas helps DIY air sealers focus effort where impact is greatest and techniques are most proven.
Attic Air Leakage Hot Spots
Recessed Lighting Fixtures:
Older recessed lights create significant air leakage through gaps around fixtures and through the fixtures themselves. Non-IC rated fixtures cannot have insulation in direct contact, creating thermal bypass areas.
Sealing Techniques:
- Install airtight IC-rated LED retrofit kits in existing fixtures
- Build sealed boxes around non-IC fixtures using drywall and caulk
- Fill gaps around fixture housing with fire-rated sealant
- Never place insulation directly against non-IC fixtures
Electrical and Plumbing Penetrations:
Holes cut for wiring and plumbing are often oversized, creating gaps around pipes and cables passing through framing members.
Sealing Approaches:
- Use expanding foam around smaller penetrations (under 2")
- Install rubber grommets or boots around pipes and conduit
- Fill large openings with rigid foam pieces sealed with expanding foam
- Apply fire-rated sealants around electrical penetrations per code requirements
Attic Access Openings:
Pull-down stairs and access hatches typically lack adequate weatherstripping and often warp over time, creating significant gaps.
Improvement Methods:
- Install high-quality weatherstripping around entire perimeter
- Add spring-loaded mechanisms ensuring tight closure
- Build insulated covers for pull-down stairs
- Consider upgrading to insulated, gasketed access systems
Basement and Foundation Air Leaks
Rim Joist Areas:
The connection between floor systems and foundation walls creates numerous air leakage opportunities through gaps in framing and around utility penetrations.
Comprehensive Sealing:
- Install rigid foam insulation cut to fit tightly between joists
- Seal foam edges with expanding foam or caulk
- Fill utility penetrations with appropriate sealants
- Address any gaps in sill plate connections
Foundation Penetrations:
Utilities entering homes through foundation walls often have oversized holes with minimal sealing around pipes, conduits, and service lines.
Professional Techniques:
- Remove old, deteriorated sealing materials
- Size openings appropriately for utilities
- Install rubber boots or grommets for movement accommodation
- Apply high-quality sealants suitable for foundation conditions
Door and Window Air Leakage
Door Frame Issues:
Doors experience significant air leakage around frames, especially at thresholds and along hinge and latch sides where weatherstripping wears or becomes misaligned.
Comprehensive Door Sealing:
- Install high-quality weatherstripping appropriate for door type
- Adjust door alignment to ensure proper weatherstripping contact
- Install or upgrade door sweeps at thresholds
- Seal gaps between door frames and rough openings
Window Air Leakage:
Windows develop air leaks through weatherstripping deterioration, sash misalignment, and gaps between window frames and wall framing.
Window Sealing Strategy:
- Replace worn weatherstripping with appropriate materials
- Adjust sash alignment for proper seal contact
- Caulk gaps between window frames and interior trim
- Consider storm windows for additional air sealing and insulation