Preventing outside elements like air and water finding their way into your house.

To increase comfort and save on your energy bills, it’s necessary to assure that the outside elements like air and water don’t find their way into your house.

The first step to weatherization is testing for air tightness. A professional blower door test works the best. However, you can self test to find major air leaks on a windy day by holding a smoking incense stick in front of and around windows, doors, attic or crawl space hatches, electrical outlets, plumbing penetrations, dropped ceilings, and ceiling fixtures. You will be able to see an air leak if the smoke travels in a straight line instead of a cloud.

If you do find leaks, here are some suggestions for dealing with them:


Improvement Suggestions

Dropped ceilingAir seal ceiling above with canned foam or caulk
Recessed light housingsHave professionally air sealed with high-temperature silicone sealant or replace with properly installed new light can
Attic and crawlspace hatch coversWeatherstrip and caulk around frame perimeter. Add insulation to the hatch.
Foundation sill plate jointsSeal with caulk or foam.
Water and furnace flues, plumbing ventsSeal with expanding foam or caulk. If joint is too large, stuff with fiberglass insulation, and spray foam over the top to seat the surface of the plug.
Duck boots and registersCaulk or foam the joint between the boot and the ceiling, wall, or floor.
Duct chasesHave professionally sealed
Doors and door framesMake sure the doors close properly. Weatherstrip and caulk.
Masonry chimneysSeal sheet metal flashing with a high temperature sealant or chimney cement.
Window framesMake sure they close and latch properly. Weatherstrip and caulk.
Electrical outlets and switchesAdd preformed foam gaskets from hardware store. Insert childproof caps.
Plumbing and utility accessSpray foam insulation at penetrations in floor, crawlspace, and attic.


There are some tasks better left to professionals:

  • If a duct test determines leaking heating ducts, have them professionally sealed.
  • For air leaking through canned lighting fixtures, it’s recommended to replace them with properly installed newer sealed fixtures or have them professionally air sealed with high-temperature silicone sealant.

Keep out the draft in winter

If replacement with newer, more energy-efficient double and triple-paned models is not an option, consider installing storm windows over single-pane windows. Storm windows may effectively double the R-value of a single-pane window and can help reduce drafts, water condensation, and frost formation.

As a less costly and less permanent alternative in the winter, you can use a heavy-duty, clear plastic sheet on a frame or tape clear plastic film to the inside of your window frames. Remember that the plastic must be sealed tightly to the frame to help reduce infiltration. Follow the instructions on the package if it calls for using a hair dryer to shrink the plastic in place.

Install window treatments and keep them drawn to hold in the heat during the winter and keep out the heat on those hot summer days. There are materials available with insulating properties made just for this purpose.

For more suggestions and resources, see Clark Public Utilities’ information on Reducing Home Air Leaks.

Weatherization Assistance

Find out if you qualify for the Weatherization Assistance program, which is free to qualified low-income homeowners and renters, and provides energy efficiency and indoor air quality improvements for single-family, multifamily, and mobile homes.