Home Energy Retrofit Guide: Air Sealing and the Building Envelope

A chill is in the air, is last place you want to feel a cold draft is in your house. That’s why ensuring that the building envelope of your home is sealed correctly is so important – not only for your personal comfort during the winter months but also for the good of your wallet.

What’s so important about air sealing?

Hot air leaking from your home means you’ll be cranking the heat more frequently, contributing to higher utility bills (and a greater carbon footprint).

However, in order to adequately address the problem of heat loss and increase the energy efficiency of a home, understanding the structure (more specifically, the building envelope) of your house is critical.

What constitutes the building envelope?

The building envelope includes the windows, doors, roofs, walls, foundation and insulation. These pieces all create a physical divide between the conditioned internal area of a building, from the unconditioned outer environment. Keep these key areas in mind when addressing air loss in your home, as the building envelope plays a monumental role in increasing your energy efficiency.

What you can do to prevent cold air from entering your home?

There are plenty of areas where air leakage is common in residential buildings. The image below shows some of the most frequent spots that you may find a draft present.

You can address air leakage in your home both through Do-It-Yourself (DIY) methods, or by contracting professional air sealing services to help you. In the section below, we will highlight some key areas of the home where air leaks are found, and some practical tips for addressing them.

Attic Hatch

Before beginning air sealing measures, ensure that the hatch itself is insulated. It should be more than just a piece of plywood that covers the opening to your attic! Next, you’ll need to purchase some basic materials for air sealing – a caulking gun, sealant, and some weatherstripping. Using the caulking gun, you’ll want to place a line of sealant along the edge of the entirety of the ceiling drywall that is cut open for the hatch. 

Then, place the weatherstripping material along the cracks between the attic hatch and your ceiling. You may also want to purchase some hook latches to secure the attic hatch (and weatherstripping) flush against the ceiling.

Plumbing Stack

The plumbing stack is the central pipe that vents out through your attic to the roof. It is used to regulate air pressure inside your pipes to keep water flowing smoothly throughout the plumbing of your house. It is also a very common area for air leaks.

To seal this area, you’re going to need to purchase either a plastic polyethylene sheet or a rubber pipe collar to go around the plumbing stack.

If using a rubber or neoprene collar, you’ll need to cut the pipe and then slide the collar to the bottom of the pipe so it sits flush with the floor of the attic. Using a caulking gun, apply sealant underneath the flaps and along all the edges to seal the collar to the pipe and the floor.

If using a plastic polyethylene sheet, wrap the plastic around the pipe until it overlaps with itself and use sealant to connect the two sides together.

Then, apply sealant to the area where the plastic sheet touches the floor – you can staple the plastic to the floor for added security. You’ll also need to purchase a metal pipe clamp to go around both the pipe and polyethylene sheet, above where you sealed the two edges together.

If you’d like to hear more about air sealing the plumbing stack (and other common areas), check out our virtual webinar with green building expert, Dave Braden, on our Green Venture YouTube channel.

Electrical Outlets

One commonly overlooked area where small drafts exist are the electrical outlets in your house.

Before performing any air sealing measures to electrical outlets, ensure that the power to that area is switched off on your circuit breaker.

To seal your outlets, you’ll need to purchase a package of foam gaskets that can be placed between the outlet faceplate and the exposed electrical outlet (you’ll need a screwdriver to unscrew the faceplate). You can also prevent any excess drafts by purchasing some plastic child-safety plugs to go into outlets that you rarely use. 

If you are undergoing a home renovation and have access to the wiring that connects to the outlet, you can purchase a plastic casing made for air sealing electrical outlets from a hardware store. Simply stick the wires for the outlet through the plastic casing, and then use a caulking gun and sealant around the opening that the wires came through.

You’ll also want to use the sealant to connect the plastic box to the polyethylene vapour barrier surrounding the rest of the wall that the outlet is on.

Windows and Doors

Another key area where drafts are most likely to be found is around windows and doors that lack proper air sealing. To address this issue, you can use a variety of air sealing materials that can be found at hardware stores, and are often inexpensive.

Weatherstripping material is the most commonly used to create a seal between the frame and the window or door. Compression strips are one type of weatherstripping material, typically made of foam, rubber, or vinyl, and come with an adhesive backing. Use compression strips to add a better seal to a window closure, or in the crack between a door and the hinges.

You may also want to use a caulking gun to add a line of sealant to the compression strip to keep it secure, and you can staple it to the frame as well. If you notice a persistent draft, you may have larger gaps behind the trim around your windows or doors. You can remove the trim yourself and seal any large cracks between the frame by purchasing a foam backer rod and placing it in the gap, then adding sealant over top. 

To stop drafts from coming in underneath a door, you can attach a door sweep (typically made of silicone, rubber, vinyl, or brush material) to the bottom of your door. Keep in mind that it will need to be replaced periodically. Additionally, Installing a metal threshold strip to the floor will also create a greater seal in combination with the door sweep.

Contracting Professional Services

If you decide that the DIY methods listed above are not in your purview, or that there are areas of your home that are too complex to seal using DIY methods, you may want to enlist the help of professional air sealing services. This type of service may also be described as “draft-proofing” or  “weatherization”. There are a variety of companies and contractors that specialize in this area, feel free to check out the resources we’ve compiled below to help you in your search for a contractor. 

Hiring A Contractor – Green Venture’s Website

Contractor Information for Homeowners – Green Communities Canada

We also maintain and continually update a list of local contractors, email us at [email protected] to request a copy. 

Having a hard time finding those pesky leaks? 

Green Venture offers home airtightness assessments -- contact us to learn more!

The Building Envelope in a Deep Energy Retrofit (DER)

Addressing gaps in the building envelope through significant air sealing measures is one of the ways that you can participate in a Deep Energy Retrofit (DER). A DER focuses on the structural and operational aspects of a building in order to make large improvements in energy performance. 

When paired with major air sealing, improving the building envelope by increasing insulation levels in all areas of the house and ensuring adequate ventilation will reduce your average energy use at home by 30-50%.

Green Venture is here to help!

With our EnerGuide energy auditing service, our Registered Energy Auditors (REAs) can provide you with a comprehensive home assessment so you can better understand where your current energy use stands, and how to start making improvements for a more comfortable and energy-efficient home. 

To book an energy audit with us, please send an email to [email protected] or call 905-540-8787.

Sources and Further Reading: 

Natural Resources Canada (2024). “Keeping The Heat In - Section 4: Comprehensive air leakage control in your home”. https://natural-resources.canada.ca/energy-efficiency/homes/make-your-home-more-energy-efficient/keeping-the-heat/section-4-comprehensive-air-leakage-control-your-home/15635 

Green Venture Hamilton, “Energy Efficient Houses: A Guide to Small Changes for a Big Impact”. https://youtu.be/kriEI9-2HNY?feature=shared