House Energy Site

air sealing for home comfort

Be aware to air leaks. They can be a lot more than just a cause of lack of comfort; they may also be a cause of moisture, low-quality indoor air and high energy bills.

The home's envelope should be sealedHomes Should be Very Airtight and Super-Insulated

Homes should be airtight.

Older wood-frame homes may lose as much heat through air leakage as they do by heat conduction through their walls and other parts of their envelope.

Homes Do Not Need to "Breathe"

Homes do not need to breatheHomes do not need to "breathe". Popular horror stories about air-tight homes are misplaced.

Air leakage and construction defects are the ultimate causes of moisture problems. Not the fact that homes are airtight...

Air-tight vs. Leaky Homes

Air Sealing vs. Insulation 

best air sealing contractorsCaulks, Foams, Air Barriers, Weatherstrips and Insulation Materials for Energy Improvement

There are four main types of air sealing materials, responding to different needs:

» Caulks - silicone, urethane, latex....- for small gaps and holes;
» Foams for medium-sized openings;
» Air barriers for larger openings;
» Weatherstripping materials to air seal movable parts in doors and windows.

Most standard insulation materials - fiberglass, cellulose... - are not effective at sealing leaks, and many attics, with their dirty insulation, are a good illustration of this point. It shows that insulation is acting as an air-filter, and that it doesn't stop air from flowing.

Types of Air Sealing Materials 
Caulks, Foams and Their Application

Wood Frame Homes: The More Important Air Leaks Are Often in the Attic and BasementAir Leakage Data

In wood frame homes, the more important air leaks are often hidden and go unnoticed; they are in the attic and in the basement.

People are often more aware of small openings and cracks around doors and windows, or fireplaces or chimneys, than of infiltration and energy loss through the attic, crawlspaces and basements...

Attic and Basement Air Leaks 
Attic Air Sealing
Basement Air Sealing

caulkingWindow and Door Caulking

Small leaks around windows and doors can be sealed with acrylic and acrylic-latex caulks; they are easy to apply and to wash up with water. They seal well and are perfect for indoor uses.

See: Window and Door Caulking

weatherstripsWindow and Door Weatherstrips

Weatherstrips vary with the type of windows and doors.

Weatherstripping a casement window or a double-hung window involves different materials and methods... Weatherstrips come in several sizes, shapes and materials: metal, vinyl, plastic, rubber, felt, foam (or a combination of some these materials).

Weatherstripping Windows
Weatherstripping Door Bottom
Weatherstripping Door Sides

Ventilation and fresh airAir Leaks, Ventilation and Fresh Air

Modern energy-efficient homes should not rely on air leaks to get fresh air. The gaps and holes where air leakage occurs are full of pollutants. To get fresh air, in cold climates, in low-energy homes, you need a mechanical ventilation system.

It’s a bad idea to rely on air leakage for ventilation. You will get too much cold air during windy weather, particularly in the winter, when it is not wanted; and too less fresh air, during other periods. And you will have to contend with poor indoor air quality.

Air-tight vs. Leaky Homes

Mechanical Ventilation Systems Guide

Best air sealing and insulation auditsWhere and How to Look for Air Leaks

You can carry out yourself some easy tests to identify air leakage paths.

But, in wood frame homes, you may need a professional energy audit; the best way to find your home’s air leaks is by performing a blower door test.

Tests to Find Air Leaks 
Energy Audit Guide

Moisture controlMoisture Control & Sealing

Airtightness is critical to control home moisture. Ventilation (mainly when done through air leaks) is not of great help...

Air Sealing & Moisture and Energy Efficiency
Moisture Control Guide

economics of air-sealingThe Economics of Air Sealing

Air sealing is one of the best home improvement investments that you can do in wood-frame homes, in cold climates..

Payback periods can be very short and the energy improvements high.

See, for details: Home Air Sealing: Paybacks

See also:
Online Resources on Air Sealing
Super-Insulated Homes
Insulation Guide for Energy Efficiency
Resnet Air Sealing Contractors
New Low-Energy Homes Guide


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Our Video on Air Sealing:





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