Home Tightening

Energy Myth: It is dangerous to tighten up a house too much.

Fact: It is almost impossible to make a house too tight. Reducing air leakage in an existing home is easy and cost effective. If the air in the house is too "stuffy" then increase ventilation (something that you can control)-don't depend on uncontrollable air leakage.

Home Series Booklet: Home Tightening (PDF)

Quick Tips

  • Tightening your home can cut energy waste and save you up to 40% each year on heating and cooling costs. Inspect you home for air leaks. On a cold, windy day, turn on all exhaust fans and the clothes dryer to draw air out of the house so that outside air will be pulled in. Then place your hands (or tissue paper or thin plastic) around windows, doors, electrical outlets and switch plates to check for air leakage. Note where leakage is taking place and prioritize from the big leaks to the smaller ones. Take special care to look at the high and low air leaks. See pages 2 and 3 of Home Tightening and pages 8 and 9 of Energy Savers.
  • Plug the big leaks now. Large leaks are often tucked away in unlikely spots around chimney pipe openings, recessed lights, wiring and pipes. When added up, these leaks could easily be the size of an opened window. It does not take any special equipment to plug a large leakage area. Temporarily plug a large air leak with anything handy. Later, when materials become available, replace the temporary fix with a more permanent one. See page 30 of Home Energy Projects.
  • Close and seal the fireplace damper. Make sure that the chimney is sealed as air-tight as possible when not in use. This can be done with a "plug" of foam or even cardboard. Ensure that nobody lights a fire after this is done. See page 6 of Home Tightening.
  • If it is winter and you have a room air conditioner, remove it or seal it up for the winter.

Doors and Hatches to the attic:

  • Weatherstrip the edges of the attic hatch and insulate the backside of the door with two or more inches thick of foam insulation. Fold down stairs can be covered with a lightweight box made of rigid insulation. See page 4 of Home Tightening.

Windows and Doors:

  • Caulk around windows and exterior door frames. See page 8 of Home Tightening.
  • The places where doors and windows close into their frames can be sealed with weather stripping. Strips of felt, rubber, metal or plastic and be purchased that fill the spaces between the frame and the doors and windows, and compress when you shut them. See page 11 of Home Tightening.
  • If you have windows and other places that you will want to be able to open up again in the summertime and they are not air tight, use rope caulk. This is a gray, putty-like material that is easy to work with, remains flexible, and can be removed with the weather turns warm. See page 7 of Home Tightening.
  • Use caulking to seal medium to small air leaks. Seal the leaks that are high (ceiling, attic hatch) and low (holes in the floor and around the sill plate.) See page 7 of Home Tightening for a description of common caulking materials and their uses.
  • Follow "The Air Leak Checklist" on pages 4, 5 and 6 of Home Tightening. This is a comprehensive list of the areas to check and how to seal each one of them.
  • Use filler materials such as foam and sponge rubber to fill large cracks-then cover this material with caulk. This reduces the cost of the caulking. See page 7 of Home Tightening.
  • Replace worn-out weatherstripping around exterior doors. See pages 10, 11 and 12 of Home Tightening for an explanation of the variety of materials for this purpose.
  • Windows can account for 10 to 25% of your heating load. For existing homes with single pane windows, add storm windows. For replacement windows or for new construction see pages 18 and 19 of Energy Savers and pages 15 through 18 of Home Tightening. Excellent information on the energy features of all types of windows can be found at the Efficient Windows Collaborative link below under "Other Links and Resources."


  • Duct leakage may account for 10-20% of a home's total air leakage. Have air leaks professionally sealed with mastic (a non-toxic paste) and wrap metal ducts with two inches of insulation to reduce thermal loses. See page 17 of Home Insulation.
  • In homes with forced air heat there may be large cracks or gaps that need to be sealed where the ducts pass through the ceilings, floors and walls. See page 4 of Home Tightening.


  • If you never use your fireplace, plug and seal the chimney flue. See page 6 and 12 of Home Tightening and pages 31 and 32 of Home Energy Projects.
  • Keep your fireplace damper closed unless a fire is going. Keeping the damper open is like keeping a 48-inch window wide-open during the winter. Note: a fireplace is an inefficient heating system because it will rapidly draw heated air up the chimney when in use and when not in use, a poorly sealed damper is like having a hole in the ceiling. To improve efficiency of wood combustion, consider installing a wood-burning insert that pulls combustion air from outside. See page 12 of Home Tightening.


  • Keep your home investment by maintaining the condition of the roof and exterior paint. Cracked or peeling paint allows moisture to build up which may eventually give rise to air leaks. Also inspect your roof for leaks. A typical roof lasts 15 years. If yours is older, it might be ready to be replaced.
  • If a fireplace is being used then: check the seal of the flue damper, install tight-fitting glass doors, caulk around the fireplace and hearth, and use cast-iron firebacks. See pages 12 and 13 of Home Tightening.
  • Exterior doors get a lot of use and a professional might be needed to properly install weatherstripping and a door sweep or threshold. A good solid-core door is heavy and a professional can properly install it so that it will provide years of service. See pages 14 and 15 of Home Tightening.
  • Storm windows or, better yet, replacement windows will not only help reduce air leakage they will lower heating and cooling costs. See pages 15, 16 and 17 of Home Tightening. Check out the Efficient Windows Collaborative link below under "Other Links and Resources."
  • A few businesses provide a specialized air leakage test using what is called a "blower door." This is a very accurate and fast way to determine where air leakage is occurring. See page 3 of Home Tightening.