Sealing Air Leaks: Low-Cost Way to Improve HVAC Efficiency

Air leaks let conditioned air escape and unconditioned air in. Sealing them is cheap and effective.

Common Leak Locations

Attic - Around plumbing and electrical penetrations - Attic hatch or pull-down stairs - Recessed lights - Duct connections

Walls - Electrical outlets and switches - Window and door frames - Where walls meet foundation or attic

Basement/Crawlspace - Rim joist area - Utility penetrations - Foundation cracks

Finding Leaks

DIY Methods - Feel for drafts on windy days - Hold incense near suspected areas—smoke reveals air movement - Look for dirty insulation (indicates air movement)

Professional Testing A blower door test measures overall leakage and helps locate specific problem areas.

Sealing Materials

Caulk Best for: - Gaps up to 1/4 inch - Stationary joints - Around windows and doors

Weatherstripping Best for: - Movable components - Doors and operable windows - Attic hatches

Expanding Foam Best for: - Larger gaps - Irregular shapes - Around pipes and wires

Foam Board Best for: - Large openings - Behind kneewalls - Covering attic hatches

DIY Air Sealing Project

Start in the Attic The biggest impact with least disruption.

**Steps:** 1. Create a safe working platform 2. Seal around all penetrations (pipes, wires, ducts) 3. Seal the attic hatch 4. Address recessed lighting (if present)

Then Move to Basement/Crawlspace Seal the rim joist area and any penetrations.

Finally, Living Space - Add outlet gaskets - Caulk window and door trim - Apply weatherstripping

Expected Results

Typical air sealing reduces energy use by 5-15%. Combined with insulation improvements, savings can reach 20-30%.

When to Hire Help

Consider professional help for: - Comprehensive whole-house sealing - Hard-to-reach areas - Homes with significant leakage