Walls and Roofs

Walls and roofs are composed of many components that each serve a specific function, and work to protect from the elements, provide insulation and retain either the heat or coolness of a home. In fact walls, can account for about 20% of heat loss in homes. The external factors that affect your the longevity roof and walls include its external surroundings, sun exposure, and general weather conditions.



It’s important to understand the components of your exterior wall. These include:

  1. Exterior Cladding

  2. Drainage Planes

  3. Air Barrier Systems

  4. Vapor Retarders

  5. Insulating Elements

  6. Structural Elements

Image obtained from: Wix images

Thermal siding can bridge the gap between the façade and the wall to ensure there are no air pockets that increase thermal gradient for heat loss


Find the right type of retrofit that fits your budgets, performance and  energy needs.


Minor retrofits are small changes that you can make to your home, including leak and gap sealing and installation of the storm door.

A major retrofit takes on a more holistic approach that is higher in costs such as use of automatic doors or glazing doors.

Deep retrofits is more extensive and costly such as adding insulation to walls.

When working on a wall and roof retrofit it is important to always use a certified building specialist or contractor to maintain the structural integrity of your building envelope.

Wall Assembly.png

Elements of an exterior wall.

Image obtained from: WBDG - Whole Building Design Guide, click on image for reference

Wall Assembly

Exterior Cladding: This is your primary line of defense against the natural elements. Generally, in Ontario homes this is brick. It serves as a protective ‘skin’ to the interior and structural components of your home.

Drainage Planes:  It is also known as the WRB (water resistant barrier). There is usually a cavity between this and the exterior cladding. This controls penetrating rainwater by directing it down and away from the home. They are of water repellant material and most commonly, house wrap or building paper. Since the purpose is to repel water, drainage planes can come in many other ways such layering rigid insulation that is water resistant.

Air Barrier and Vapor Retarder:  The air barrier is designed to resist movement of air across the assembly. It is important to note that an effective barrier is to be continuous across the envelope (from roof to wall to foundation). Air retarders resist or slow down the rate of airflow across but cannot alone, act as the air barrier. The vapor retarder act as a second line of defense against moisture by limiting the flow of vapour water across the assembly.

Insulating Elements: The insulating element regulates heat loss and gain. There are many different options for insulation here such as blown-in insulation, rolls and batts, rigid foam insulation, etc.

Structural Elements: These are elements that work to resist load whether it be horizontal loads like wind or vertical loads like dead loads from your home itself.

Remember, these are the basics and that these elements need to work cohesively as an assembly to have an effective wall. Roofs and walls share very similar assemblies. When looking at roofs, the main focus will mostly be on roofing type. These include your traditional asphalt roofing, fibreglass asphalt roofing, wood shingles, metal, and slate roofs.


Images obtained from: Wix images

A lot of housing stock is decades, even centuries old. Building retrofits bring these older homes up to date with modern construction while maintaining diversity of housing in our community


1. Keeping The Heat In - Chapter 7: Insulating Walls (nrcan.gc.ca) Canada NR. Government of Canada [Internet]. Natural Resources Canada. / Gouvernement du Canada; 2016. Available from: https://www.nrcan.gc.ca/energy-efficiency/energy-efficiency-homes/how-can-i-make-my-home-more-ener/keeping-heat/keeping-heat-chapter-7-insulating-walls/15641

2. Components of a Good Roof System: Smart Roofing - Toronto, Etobicoke, Mississauga, GTA [Internet]. Smart Roofing Inc. 2020. Available from: https://www.smartroofing.ca/roof-system-articles/components-of-a-good-roof-system/

3. Wall Systems | WBDG - Whole Building Design Guide Lemieux DJ. Wall Systems   [Internet]. WBDG. 2016. Available from: https://www.wbdg.org/guides-specifications/building-envelope-design-guide/wall-systems

4. Understanding Drainage Planes | Building Science Corp BSD-105: Understanding Drainage Planes [Internet]. Building Science Corporation. 2006. Available from: https://www.buildingscience.com/documents/digests/bsd-105-understanding-drainage-planes

5. Insulation: Choosing the Best Fit for Your Home - Efficiency Nova Scotia (efficiencyns.ca) Insulation: Choosing the Best Fit for Your Home [Internet]. Efficiency Nova Scotia. 2020. Available from: https://www.efficiencyns.ca/tools-resources/tip/choosing-home-insulation/

6. 5 Roofing Options for a New Home in Ontario - Royal Homes 5 Roofing Options for a New Home in Ontario [Internet]. Royal Homes. 2018. Available from: https://www.royalhomes.com/tip/5-roofing-options-for-a-new-home-in-ontario/