DIY Air Sealing

Sometimes I get so frustrated by the things I can’t control that I need to channel my energy towards things I can do something about.

I’ve had air sealing on the list for the last few weeks (ever since I audited my home as a part of my energy advisor training). A few weeks ago I tackled it. I want everyone to know that you don’t always have to spend thousands of dollars to reduce your home’s emissions. Up to 40% of home’s heating is lost to air leaks. Air Sealing is something you can (and should) do right now.

First a few words of caution - you should always wear protective equipment. A mask and gloves are advised, especially when working with spray foam. 

Second - Do your research and take the time to understand how air, heat and moisture flow through your home before you start running around and sealing up every nook and cranny. If you seal things without understanding how your home works you may, at worst, create problems with moisture and airflow and at best may spend a lot of time and money without really moving the needle on your air leakage. When in doubt ask a professional!

An excellent resource is one from Natural Resources Canada called ‘Keeping the Heat In’. If you don’t have time to read it all, just read the section on air leakage. 

Why do small cracks cause a lot of heat loss? Two things need to be present for heat to be lost through air leakage. First, there needs to be cracks or spots where air can leak out. This may be obvious but it’s helpful to think about why they exist and where they may have come from. Most newer homes have an air barrier, for the wall portion of our homes this is most often house wrap. For it to be effective it needs to be continuous. Think of it similar to those stylish fanny pack windbreakers we all owned in the 80s. 

When someone installs new pot lights in the ceilings, or gets a new air conditioner installed, these are more holes in our home’s K-Way Wind Breaker (or air barrier for the more technical folks reading this). If the installer doesn’t take time to seal this penetration properly, it may be a likely culprit for air leakage. 

I mentioned that two things need to be present for heat loss by air leakage. The second is a pressure difference. Our homes are naturally depressurized relative to the outside. Wind blowing on one side will naturally depressurize a home. Anytime we run an exhaust fan we are depressurizing our home (think of it like drinking from a plastic bottle without pausing to let air go into the bottle). The most common cause of depressurization comes in the winter. Hot air is lighter and so will rise and when it does it finds nice little leaks for it to flow through (like through those pot lights in the ceiling of our top floor). Then to make up for the air that was lost, cold outdoor air will come in through the basement, mix with the indoor air and the cycle continues.

Your home may be a good candidate for DIY Air Sealing if:

• You’ve had an energy audit and received a list of air leakage locations from the auditor.

• You’ve done your research and understand the stack effect

• You consider yourself somewhat handy

Common Sources for Air Leakage Source: Keeping the Heat In, NRCan

Okay now that the science lesson is done, onto the fun part. Doing the work! First, head to your local hardware store. Pick up a few cans of spray foam, some indoor/outdoor caulk (think about where you’ll be using it and what colour you’d like), some foam gaskets for your outlets and weather stripping for those drafty doors.

Start outdoors and examine all the spots where something goes from the outdoors to indoors - an exhaust fan, the internet cable, your power, exhaust from your furnace, to name a few. Check how well sealed they are and top up if necessary.

Then head indoors. If you have an attic, you’ll want to start there and first look at your hatch. Does it have weather stripping and a latch? Then into your attic we go! For every pot light and other penetration into the attic, check how well sealed they are. Spray foam works well in attics because no one will see it and it does an excellent job. A word of advice on spray foam - if it gets on your clothes or anywhere you don’t want it to go, don’t try and wipe it up. It’ll only make things worse. Wait until it dries and then it’ll crack off (although for clothes you’ll never be able to get all of it off). Gloves are also a really good idea when using spray foam.

Then head to your basement. If your basement is unfinished, seal up the spot where your basement wall meets your main floor subfloor (these are your headers and they are often a culprit for intake air). Sometimes, you might find it helps to shove some insulation between the headers first and then seal around the insulation to both hold it in place and to make sure you don’t end up using an entire $20 can of spray foam on one little area.

Last, tackle any doors or windows that you know are leaky with weather stripping and caulk as relevant.

Good luck and if you’ve had an audit done, you may now qualify for the air sealing rebate currently on offer from Enbridge (you need to do two things on your home to qualify).

I’m always happy to provide 10 minutes of free advice or support to anyone who is interested in air sealing so please don’t hesitate to contact me at sgrant@goldfinchenergy.ca.