Air Infiltration

Your home can have over a kilometre of cracks in it! They are located anytime you have different building materials coming together. If it’s a new home under construction, there are a number of things you need to check:

New Homes:

• Check around windows and doors
• Use a good silicone caulk to seal cracks. Latex caulking can be painted.
• Ensure that doors have weather stripping to make sure that it’s filling the gap at the bottom and around the rest of the door.
• Check your fireplace to ensure the damper is closed when you’re not burning wood in it, so you don’t have a lot of heated or air-conditioned air going right up your chimney.
• Check wall switches and outlets. You may need gaskets under the plates or even want to plug in plastic inserts that a lot of people use for child protection.
• Check for cracks where different types of building materials come together.
• Check protrusions of the building envelope surfaces e.g. walls, roof, ceilings, where ducts, pipes, chimneys are located. Homes with naturally drafted combustion appliances may allow air leakage from these holes to cause back drafting of the appliance.
• Check the bottom of walls where they meet the floor, and the first floor / foundation wall joints at the sill plates.
• Cracks larger than one-quarter inch should be filled first with something like foam insulation before caulking.

Air Infiltration Tests:

• Blower Door Test — If you’ve checked the above and your house still feels like drafts are present or you have unusually high heating / cooling bills, consider having a blower door test done to check for excessive leaks.
• Infrared Test — You can also have an infrared test done if you think your walls may be lacking insulation. It’s a great way to pinpoint leaks, but it is pretty expensive.

Is your Home Too Airtight?

• Some homes are being built so airtight that getting enough fresh air in the home can become a concern.
• If you have oil or wood burning heaters that draw air from inside the home to burn, making sure you have enough fresh air coming into the home is very important.
• If you just get the feeling once in a while that a room is getting too stuffy, open a window for a few minutes once or twice a day.
• All homes must have some minimum amount of air exchange in order provide oxygen for people and appliances, to control humidity, eliminate odours, etc. Although some homes experience problems due to insufficient air exchange, often homes leak more than necessary most of the time. Mechanical ventilation such as exhaust fans or heat recovery ventilators (HRV) are good method of controlling air exchange.
• Older houses tend to leak the most air and it is not unusual for all the air in the home to be replaced every hour. One general rule of thumb is to have a minimum air exchange rate of about a third of the home’s per hour. Some very energy efficient houses are being built with leakage rates as low as 0.05 air changes per hour, using controlled mechanical ventilation to ensure the health and comfort of the occupant.

Benefits of Reducing Air Infiltration:

• Reduce energy use.
• Improve comfort, health, and building durability.
• In winter, less cold, outdoor air would replace heated air, reducing drafts and cold areas.
• In summer, more hot, humid air would be kept out of the house.
• Pollen, dust, and possible radon entry can be reduced.
• Reduced moisture levels in walls and attics decreases the chances of structural damage resulting
• Possible downsizing of heating / cooling equipment when replaced.

Other Concerns With Tightening Up Your House:

• Moisture is produced by a number of sources in the home including cooking, bathing, and, plants. When a home is tightened, the humidity almost always increases. Controlling all sources of moisture can be critical in a tight home to prevent condensation on windows, walls, etc.
• Proper drafting of combustion appliances is critical for health and safety reasons. Drafting can be greatly affected by the tightness of your home. Tests can be performed to determine if back drafting occurs in your home.