Air Sealing Estimator

Air leaks are the invisible reason your home is drafty and your energy bills are higher than they should be. Answer a few questions and find out what sealing your home could do.

Why air leakage matters more than most people realize: Insulation slows heat — but air carries heat. In a typical older home, uncontrolled air leakage accounts for 25–40% of heating and cooling costs. You can have great insulation and still lose a significant amount of energy through gaps and bypasses that insulation alone can't fix.

Tell Us About Your Home

Older homes are typically much leakier.
Pick the closest match to your location.
Your yearly spending on gas, oil, or electric heat.
Your yearly spending on air conditioning.

Check every symptom that applies to your home:

Your Estimated Home Leakiness

— Est. Energy Lost to Air Leaks
— Estimated Annual Leakage Cost
— Potential Annual Savings
— Bill Reduction Potential

🌡️ What This Means for Your Comfort

Where to Seal First (Biggest Impact):

1

Attic floor penetrations — gaps around light fixtures, plumbing stacks, wiring, and wall top plates. Often responsible for 30–40% of total air leakage.

2

Rim joists — the band of wood where your floor framing meets the foundation. A major source of cold air infiltration in winter.

3

Penetrations in exterior walls — around pipes, electrical boxes, recessed lights, and HVAC connections.

4

Door and window weatherstripping — check compression seals on doors and the gap between window frames and rough openings.

5

Fireplace damper and chase — open flues and leaky dampers can be major sources of heat loss in winter.

Honest context:

The Building Science Behind Air Sealing

Air moves through buildings because of pressure differences — driven by wind, the stack effect (warm air rising in winter), and your HVAC system. Every gap and crack is a pathway. Unlike a window or door you can close, most air leaks are hidden inside walls, in the attic, and at the foundation.

The stack effect is particularly powerful in winter: warm air rises and escapes through the upper half of the house, pulling cold air in through the lower half. This is why you often feel drafts near the floor and why the attic is the highest-priority place to air seal — it's where warm air exits.

The building science principle is "build tight, ventilate right." Sealing uncontrolled leaks doesn't mean the house can't breathe — it means replacing random, unfiltered infiltration with controlled, intentional ventilation that you manage.

Common Questions About Air Sealing

What are the most important places to air seal?

The biggest gains come from the attic floor (around light fixtures, plumbing, and wall top plates), the rim joist at the foundation, and gaps around penetrations in exterior walls. These often account for more than half of a home's total air leakage.

Should I air seal before or after adding insulation?

Always air seal first — especially in the attic. Adding insulation on top of air leaks traps moisture and significantly reduces the insulation's real-world performance. Sealing attic bypasses before blowing in insulation is standard practice in any quality weatherization job.

Can a house be sealed too tight?

Very few existing homes are anywhere near too tight. The standard guidance is "build tight, ventilate right" — seal the uncontrolled leaks, then add controlled ventilation if needed. Most older homes would require extraordinary levels of air sealing before mechanical ventilation became necessary.

Is air sealing something I can do myself?

Some of it, yes. Weatherstripping doors, caulking around window frames, and sealing visible gaps in accessible areas are DIY-friendly tasks. Attic air sealing (around bypasses, top plates, and penetrations) takes more skill and the right materials — spray foam and caulk — but is manageable with proper preparation. Rim joist insulation and air sealing is also a good DIY project.

← Back to All Tools