Air Sealing

Reducing the amount of air that leaks in and out of your home is a cost-effective way to reduce heating costs and improve comfort. Some air sealing measures like caulking and weather stripping can be installed as do-it-yourself projects. But many air sealing projects should be installed by a professional after an energy assessment.

Air sealing in atticAir sealing reduces the uncontrolled movement of air between conditioned or heated spaces inside the home and unconditioned, unheated spaces outside. This includes eliminating gaps and cracks in the building envelope, but also the movement of air inside the home in places where you might not expect it such as around the chimney, plumbing penetrations, and recessed lights. Air sealing professionals use a variety of materials to eliminate air leakage pathways including caulk, spray foam, metal flashing, weather stripping, and rigid foam. Some materials are more suitable than others for specific locations or trouble spots. For example, fire-rated caulk and metal flashing are used in high-temperature air sealing situations like around the chimney.

Air sealing can be difficult to visualize, but everyone is familiar with the signs of uncontrolled air leakage like drafty rooms, musty smells traveling from the basement, and ice dams. Spider webs are often indicators of where there is airflow in basements and crawl spaces.

The Department of Energy has a useful cross-section diagram illustrating the most common air leakage spots. Click on the picture to see it in detail.

But the best way to learn where your home might benefit from air sealing is to consult with an energy advisor or air sealing contractor. They’ll use diagnostic equipment like a blower door to assess the relative “leakiness” of your home, locate the leaks with a smoke pencil or a thermal camera, and recommend ways to meet best practices for indoor air quality and ventilation.

Tackling air leakage in these locations and others can significantly reduce energy consumption.

Taking Action

EMvendor_100x100Find a Contractor Click here to find energy advisors and air sealing installation contractors.
EMincentives_100x100Get an Efficiency Maine Incentive — Get a $400 incentive for your air sealing project and $100 more for taking additional prescribed steps to make your home more energy efficient. Take advantage of up to $5,000 in incentives. Click here to find out more.
EMenergyloans_100x100Finance Your Building Envelope Project Click here to find out about Efficiency Maine’s Home Energy Loans for air sealing as well as energy assessments, insulation, heat pumps and more.


Financial Example

$ 850 Average Basic Air Sealing Project
$ 400 incentive from Efficiency Maine
$ 450 net installation cost

$200/yr savings
2.5 year simple payback

$4,000 savings over 20 years.
Note: Actual savings may vary.

Air sealing projects may be bundled with other energy-saving measures, and are frequently paired with insulation. Air sealing and other home performance projects including heating upgrades may be financed with Efficiency Maine Energy Loans at low 4.99% fixed APR.


  1. Comfort – Reduce drafts and cold rooms in the winter and warm rooms in the summer.
  2. Reduced Heating Demand – Minimal air sealing can reduce heating costs in the typical Maine home by 15%, and more aggressive air sealing can reduce heating needs even more. Find out how much air sealing might improve the energy performance of your home with this online calculator.
  3. Durability – Air sealing reduces movement of moisture in the home and helps maintain the integrity of your home.
  4. Low Up-Front Cost – Air sealing is one of the most affordable home performance projects a homeowner can make, and many homeowners recoup their investment within a year.
  5. Incentives and Financing – Air sealing projects are eligible for at least $400 in incentives, and may qualify for more as part of a custom energy saving project. Low-interest financing is available through Efficiency Maine Energy Loans.
  6. Environmental Impact – Reduce the carbon footprint of your home by reducing heating and cooling demand.


  1. Indoor Air Quality – Homes cannot be too tight, but they do need to be healthy and may require a ventilation system. Most Maine homes have more than three times the air flow recommended for good indoor air quality. Some air sealing projects require that building durability or indoor air quality projects be completed in advance of the installation. These projects might range from eliminating moisture intrusion in the basement to adding a heat recovery ventilation system. An energy advisor or air sealing contractor will be able to guide you through these projects. These preliminary projects may be financed through Efficiency Maine loan products. The only way to know how tight or leaky your home may be is to have it tested with a blower door as part of an energy assessment.