Basics About Sealing

Why Air Sealing Matters

Creating a secure, controllable living environment is the primary function of a building envelope. It is no surprise then that sealing plays such a crucial role in the envelope’s efforts.

Air Leaking

The enemy of comfortable homes. Air leaking is the primary consequence of poor sealing in a home. When all the components of the home envelope aren’t properly constructed together, homeowners are left with cracks and gaps in their building.

The gaps — often difficult to locate without thorough inspection — allow for temperature-controlled indoor air to escape outside. This is the source problem behind drafts and cold spots throughout homes.

Poor sealing is a problem for all seasons. Indoor temperature control is most notably necessary during warm and hot seasons, as heated and cooled air is essential for a comfortable home environment. Even then, the effects of improper sealing are felt across the calendar, allowing for energy escape at any point.

Whether a homeowner or a contractor, it’s important to do as much as possible to prevent and combat air leaking throughout the home.

Inspect The Home

All homeowners should be conscious of air leaking, and the ways they can prevent it. The best long-term remedy is thorough routine inspection.

Conduct A Sealing Inspection

Drafts and cold spots are often the best indicators of air leaks. On select household items — further detailed below — it’s important to keep an eye out for improper installation.

When doors, windows, or vents have loose screws and frames, air leaking is bound to occur. Make sure that each item on your checklist appears tightly installed and does not have any excess room for air to escape through. Both the exterior and the interior of the home need to be assessed.

These areas should be included on all home air sealing checklists:

  • Electrical Outlets
  • Door/Window Frames
  • Fireplaces
  • Attic Hatches/Drop-Down Doors
  • Faucets, Sinks, Plumbing
  • Recessed Lighting

  • Exhaust/Circulation Vents
  • Soffits
  • Flues and Chaseways
  • Cable/Phone Line Openings In Walls
  • Joists
  • Air Conditioners

Home Pressurization Test

One of the most effective ways a homeowner can check their home’s air sealing without investing too much time is through a home pressurization test.

Here are the basic steps to conduct this test:

  1. Close all doors, windows, vents, skylights, fireplace flumes, and any other primary fenestrations
  2. Turn OFF heating and cooling systems within the house (air conditioners, fans, etc.)
  3. Turn ON all exhaust fans in the house
  4. Test the home for air leaks using either:
    • lighted incense/candle
    • a wet hand (run your hand under a water faucet)
  5. Move your testing object of choice around all suspect leak locations in the house. If there is a leak, you will be able to see the incense/candle smoke drift toward the opening, or you will feel your wet hand get colder as it is exposed to cool air.

Note: This test involves a fair bit more of a time investment but is a good and thorough way to prove any suspicions surrounding specific locations.


Caulking is an excellent sealing material used to remedy small gaps and breaks in a home envelope. Available at nearly all hardware stores, caulking comes specialized for the material it is binding with. Be sure to acquire the specific kind of caulk that is required for your task.


Weatherstrips are an easily accessible solution to air leaks around common household fenestrations, like windows and doorways. The strips are applied to the open gaps between the wall and the window or door, and halt all air from seeping in or out of the location.


Proper insulation is key for good air sealing. Poorly installed installation in walls, attics, and ceilings is a common reason for air leaking to occur within a home. Check out our section on insulation for more details on this critical component in a building envelope.