Discover how much air leaks are costing you and how much you'll save with professional air sealing and weatherization.
Air sealing (also called weatherization) stops conditioned air from escaping through cracks, gaps, and holes in your home's envelope. Here's what you need to know:
Air sealing typically reduces heating/cooling costs by 10-20% ($150-400/year for average homes). It's the highest ROI home improvement with payback in 1-3 years. Some utility companies offer free or subsidized air sealing programs.
Eliminate cold drafts in winter and hot spots in summer. More consistent temperatures throughout your home mean fewer "cold rooms" and less need to crank the thermostat. Your HVAC system cycles less frequently, extending its lifespan.
Air leaks let in pollen, dust, humidity, and outdoor pollutants. Proper air sealing + controlled ventilation (like ERV/HRV systems) means cleaner indoor air. Less allergen infiltration = healthier home, especially for asthma/allergy sufferers.
Air leaks allow moisture infiltration, causing mold and rot in walls/attics. They also provide entry points for insects and rodents. Sealed homes are drier and pest-free. This is especially important in humid climates.
Air sealing should be done BEFORE insulation or HVAC upgrades. Why? Adding insulation to a leaky attic is like putting a sweater on with no shirt - air still escapes. Seal first, then insulate for maximum efficiency.
Professional air sealing costs $500-1,500 for most homes. This includes a blower door test ($200-400), materials ($100-300), and labor ($200-800). Larger or older homes with more leaks cost more. Many utility companies offer rebates or subsidized programs that reduce costs by 50-100%.
You can DIY obvious leaks (weatherstripping doors, caulking windows) for $100-200. However, professional air sealing is more effective because: (1) blower door tests find hidden leaks in attics/crawlspaces, (2) pros have spray foam equipment for hard-to-reach areas, (3) they ensure proper ventilation to avoid moisture issues. DIY first, then hire a pro for attic/basement.
A blower door test depressurizes your home to measure air leakage. A large fan fits in an exterior door frame, creating negative pressure. The contractor uses an infrared camera or smoke pencil to find where air is leaking in. Results are measured in ACH50 (air changes per hour at 50 pascals). Target: <3 ACH50 for modern homes, <7 for older homes.
Yes, but it's rare in older homes. Very tight homes (<1.5 ACH50) need mechanical ventilation (ERV or HRV system, $1,500-3,000) to bring in fresh air. Most homes, especially pre-2000 construction, are nowhere near this tight. Your contractor will ensure adequate ventilation. Combustion appliances (gas furnaces, water heaters) require special attention.
Always air seal first, then insulate. Air leaks carry 2-5x more heat than conduction through insulation. Adding insulation to a leaky attic wastes money and reduces effectiveness by 30-40%. Proper sequence: (1) Air seal attic floor, (2) Air seal rim joists, (3) Add/upgrade insulation, (4) Consider other upgrades.
Priority order: (1) Attic floor penetrations - recessed lights, plumbing vents, wiring holes, (2) Rim joists - where floor meets foundation, (3) Ductwork - seal all joints with mastic, (4) Windows/doors - weatherstripping and caulk, (5) Electrical outlets - foam gaskets behind cover plates.
Professional air sealing takes 1-2 days for most homes. Day 1: Blower door test + obvious leaks. Day 2: Attic and hard-to-reach areas. DIY projects (weatherstripping, caulking) can be done in a weekend. The work is messy (attic insulation everywhere!) but non-disruptive - you can stay in the home during work.
See how air sealing ranks against solar, heat pumps, insulation, and 18 other energy upgrades.
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