Air sealing is the systematic process of finding and sealing air-leakage points to reduce the amount of air that leaks in and out of the building. The technique is generally incorporated in the construction of buildings in countries like the USA, Canada, Russia, etc. to deal with extreme weather conditions.
It is a cost-effective way to improve comfort and indoor air quality while decreasing electricity consumption due to heating and cooling needs. The damages caused due to the moisture and air drafts within a building can be prevented by proper air sealing, hence improving the building's durability.
Air sealing is one of the essential features of an energy-efficient home. Usually, a building is air-sealed during the construction process, before installing the drywall. Air sealing the structure after installation of the drywall is a complicated and expensive process.
This article lists out some fundamental strategies to reduce air leakages and tips to air-seal a building envelope.
Need for Air Sealing Buildings
Though air circulation is essential to keep enclosed spaces free from dust and molds, it is not recommended in extreme climatic conditions. Allowing this extreme cold or hot air to move inside the building brings discomfort to the occupants.
Small air leakages in different areas of the building can add up and give the overall effect of an open window. Usually, this is solved by using heating or cooling appliances that consume high energy.
Air sealing is one of the most cost-effective measures applied to a building to improve its overall comfort level. The sealing of uncontrolled air leaks in the building decreases the dependence on heating or cooling appliances, reducing energy consumption by 10 to 20%. It is applied as a low-cost and efficient way to convert residential buildings to energy-efficient homes.
Air Sealing Strategy
Air can easily leak through an improperly sealed building envelope. Air leakage occurs when air from the outside environment enters indoors, and conditioned air leaves the building uncontrollably through cracks and openings. Air leakage decreases the occupants' comfort by letting in unwanted noise, moisture, and cold drafts. It reduces the indoor air quality by permitting airborne pollutants and dust inside the building envelope.
Air leakage is reduced by following a particular strategy that provides controlled ventilation as per the requirement. Before air sealing the building, the initial steps to be followed are:
- Detect the air leaks in the building
- Properly assess the ventilation needs for indoor air quality
Air sealing can be performed by different strategies like weather stripping, foam insulation, and caulk to tighten and seal the building's thermal envelope. The air sealing strategy aims to keep the conditioned air where it belongs.
A properly air-sealed space allows the cool air to remain indoors during the summer season. During the winter season, the uncomfortable cold air from outside is not allowed to enter the building space.
Best Air Sealing Strategies for Homes
Residential buildings have many spaces from where air can escape out easily. Before applying any air sealing strategy to the building, determine the location of common air leakage paths in the house. Some of the common paths are depicted in Figure-1. The most common air leakage locations and the ways to air-seal them are explained below:
1. Air Sealing Attics
An attic is one of the critical locations of a house that contributes to air leakage. The air in the attics heats up, rises, and escapes outside. Attics have plenty of air spaces for the air to escape, such as space around chimneys, poorly sealed soffits, etc.
Always check whether the attic location is properly sealed and insulated. Spray foam insulation or any other insulation method can be used around the vents, chimney boxes, access panels, attic hatch, and electrical boxes.
2. Air Sealing Openings Around Windows and Doors
Improper sealing of rough openings around the windows and doors would result in drafty windows. Air sealing of windows and door openings can be performed for both new installations and existing works.
Image Courtesy: The Family Handyman
The trim (material used to cover gaps in windows and doors) present around the opening is removed, and the space between the openings and the window's frame can be filled using spray foams or caulk.
3. Air Sealing Leaks Around Pipes
The leaks around the pipes are another common reason for air escaping out from the building. This is easily fixed using spray foam. Spray foam is used to fill the gaps around the pipes and the conduits. The areas around the pipes that are more prone to sweating are sealed using caulk.
4. Air Sealing Leaks around Exhaust and Whole House Fans
The location and the set up for the exhaust fan give rise to two spaces. One is through the case, and the other is through the openings in the fan. The space around the case must be sealed using a metallic tape, and the opening in the fan must be sealed using a spray foam.
The house fans present in the building must not leak air when not in operation. To ensure this, some important measures are undertaken, which are listed below:
- The covers for the house fans must be gasketed.
- The covers of the house fans must be insulated for a value of R10.
- The fan’s frame must be insulated using spray foam or caulk to prevent air leakage.
5. Air Sealing Door and Windows
The air leakage through the existing doors and windows can be prevented using weather stripping. The sealing provided must be sturdy enough to withstand friction, temperature changes, wear, and tear.
Different types of weatherstripping options are employed for different types of windows and doors. Proper installation of weatherstripping can save 20% annually on heating and air conditioning.
FAQs
Air sealing reduces the amount of air that leaks in and out of a building. This is a cost-effective way to improve comfort, indoor air quality, and reduce heating and cooling costs. Air sealing can be performed by different strategies like weather stripping, foam insulation, and caulk to tighten and seal the building's thermal envelope.
Air can leak through a building envelope that is not properly sealed. When air from the outside enters and conditioned air leaves the building uncontrollably through the cracks and openings, it is known as air leakage. Air leakage decreases the comfort of the occupants by allowing unwanted noise, moisture, and cold drafts. It reduces the indoor air quality by permitting airborne pollutants and dust inside the envelope.
The attic is one of the critical locations of a house that contributes to air leakage. The air in the attics heats up, rises, and escapes outside. Attics have plenty of spaces for the air to escape, such as space around chimneys, poorly sealed soffits, etc.
Always check whether the attic location is properly sealed and insulated. Spray foam insulation or any other insulation method can be used around the vents, chimney boxes, access panels, attic hatch, and electrical boxes.
Read More
How to Choose the Best Insulation for Buildings?
Roof Repairs - Guidelines for Repairs of Roof for Damages and Leakages
Sealing of Various Types of Joints in Building Construction(Opens in a new browser tab)