What Is Air Sealing?
Air sealing means closing every gap, crack, and unintended opening in your home's building envelope — the barrier between conditioned interior space and the outside. In Connecticut's older housing stock, these gaps are often equivalent to leaving a window open year-round.
DOE research shows that air infiltration accounts for 25–40% of heating and cooling costs in a typical home. Air sealing — before adding insulation — is almost always the highest-ROI energy upgrade available.
Air Sealing vs. Just Adding Insulation
Many CT homeowners add insulation to an un-sealed attic or basement and are disappointed by the results. Here's why: insulation slows conducted heat. It does nothing to stop air moving through gaps. Air carries far more heat than conduction — a single 1-square-inch gap in an attic can carry as much heat as a square foot of uninsulated wall.
The right sequence is always: air seal first, then insulate.
Key Areas to Air Seal in a Connecticut Home
Attic Floor Bypasses
Top plates, plumbing chases, electrical wiring, chimney gaps, recessed light cans — all are major bypass routes into the attic. Spray foam seals all of these permanently.
Attic air sealing guide →Rim Joist
The single highest-ROI air sealing project. The rim joist area is typically full of gaps between the sill plate and foundation. 2 inches of closed cell spray foam seals it completely.
Rim joist guide →Basement Sill Plate
The junction between the foundation wall and the framing above is a major air leak in most older CT homes. Spray foam seals this junction as part of basement insulation.
Electrical & Plumbing Penetrations
Every pipe and wire that passes through a wall or ceiling plate is a potential air bypass. Spray foam seals these during any insulation project.
Why Spray Foam Is the Best Air Sealing Material
While caulk and weatherstripping have their place, spray foam is the superior air sealing material for structural bypasses because:
- It expands to fill irregular gaps that caulk can't reach
- It adheres to wood, concrete, metal, and plastic
- It provides R-value along with air sealing
- It's permanent — no re-application needed
- It can be applied in tight, hard-to-reach spaces
Air Sealing Cost and Savings in CT
| Project | Average CT Cost | Est. Annual Savings |
|---|---|---|
| Attic air sealing only | $600 – $1,500 | $200 – $500 |
| Rim joist sealing (spray foam) | $800 – $1,800 | $200 – $600 |
| Whole-home air sealing | $1,500 – $4,000 | $400 – $1,000 |
Frequently Asked Questions
How do I know if my home has air leaks?
Signs include: drafts near electrical outlets on exterior walls, cold floors above an uninsulated crawl space, rooms that are hard to heat or cool, high energy bills, and dust streaks near ceiling/wall junctions. A blower door test (offered by CT energy auditors) quantifies leakage precisely.
Does air sealing cause indoor air quality problems?
A very tight home requires controlled ventilation (typically an HRV or ERV). EcoFoam will advise on ventilation requirements when air sealing significantly tightens your home. Most older CT homes are far from tight enough to need mechanical ventilation.