Air Sealing: Materials & Methods for sealing common leaks (Part 2)

In our prior articles on Air Sealing, we covered how to find the leaks inside your house, along with what tools and basic materials required to air seal your house. In this second part of this article, we will be dealing with tips & tricks on how to seal up the air leaks inside your house & some common ones outside.

Before we get started on this, we must warn you; if you feel uncomfortable, do not understand how to complete a task, etc… please call in a professional. We at SLS Construction do not want to see or hear that you have been hurt, injured or burnt down your house. If you come across areas that are moist or show signs of rot, it is time to call in a professional to fix the issue. In some cases you may already have some structural issues or if you cover up an ongoing issue, you could be easily be creating a major problem that could have easily been solved if it was taken care of when it was noticed.


  • If you have leaks that are coming in around the operable door, you need to correct that with the proper weather-stripping. (typically a compressible vinyl strip that slides into a groove located on the door jamb)
  • If you have a leak at the bottom of the door, you may need to adjust or replace the door sweep.
  • Caulk all visible cracks and gaps between non-operable parts of the doors.  Particular areas to watch for are around the door trim & threshold


  • If you have leaks that are coming in around the operable part of the window, you need to correct that with the proper weather-stripping.
  • The latches on the windows are not really meant for security, they are meant to hold the window in place against the weather-stripping.
  • Caulk all visible cracks and gaps between non-operable parts of the doors.  Particular areas to watch for are around the window trim and especially under the windowsill.
  • For older windows that utilize counterbalance weights, they can be retrofitted with Spring-Sash counterbalances allowing those sash boxes to be filled eliminating a major issue in older homes. (In an article later, I will be addressing ways to make these windows basically as energy efficient as the newer ones)

Electrical Outlets

  • If you have aluminum wiring or older style knob & tube wiring, call in a licensed electrician
  • There are three main ways to seal up a air leaks coming in around outlets
    • If you have a wide enough gap around the outlet box, you can use the expanding foam
    • You can install special foam gaskets that go behind the outlet & switch covers
    • You can also use Painters Caulk – run a bead around the inside of the cover where it meets the drywall approx ¼ by 3/16 wide (personally I suggest you use either of the first 2 options, unless you have older style wiring, then I would only consider using this method if you can’t afford to get your house re-wired)
    • If air is coming out from the electrical outlet itself, you can simply insert some child safety plugs to block it.


  • Caulk the top of the baseboard where it meets the wall
  • If you have linoleum or ceramic tile floors – you can caulk where the baseboard  meets the flooring
  • If you have carpet, floating laminate floors, etc… you will need to seal the leaks from underneath
  • Some groups advocating using expandable spray foam or caulking where there is a gap from the drywall to the subfloor – while this can be done before your final flooring is installed, it is not recommended if your flooring is already in place (Especially when you have a ceramic tile, hardwood, or a floating floor installed – you need room for the materials to expand with changes)

Recessed lights and bathroom fans

  • We first recommend installing the proper gasket for these fixture
  • If there is a gap around the fixture & the recessed light is IC rated, we would recommend you use Fire-Block expanding foam if required
  • As a last resort, you can caulk around the inside of the covers from below utilizing a high-temperature flexible caulking.

Depending on the size of the penetration, you can use the appropriate Spray foam or caulking for the following

  • Pipe penetrations under sinks
  • Electrical and gas service entrances
  • Cable TV and phone line penetrations
  • Outdoor water faucets
  • Medicine Cabinets

Bricks, siding, stucco, and foundation

  • If you have a few small cracks you can use an appropriate caulk to fill them
  • If you have large cracks, missing sections of mortar, concrete, etc… it would be best to call in a professional
  • At the bottom of the brick walls & stucco you may notice some holes – do not fill those, those are weep holes which will allow any moisture that gets behind the covering to escape

Mail chutes

  • Unless it is used, I would suggest getting rid of it properly – if it is part of the style of the house, you can still mount a fake cover plate on the outside
  • If it is still used, make sure that it securely closes on the proper weather-stripping


  • Make sure your damper works properly, if not get it repaired  or replaced
  • During the summer months, we would also recommend purchasing and utilizing Chimney Balloon
  • Nicholas Lindenmuth

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