Home Energy Retrofit Guide: Insulation

A how-to guide for increasing your energy efficiency at home by increasing your insulation.

Looking to make your house more comfortable by increasing the insulation in your home, but don’t know where to start? This guide can help! We’ll be discussing different types of insulation, how insulation is rated, and some key considerations for installing and upgrading the insulation in your home.

What is insulation?

Insulation is a thermal barrier that helps to prevent a building from losing heat during the winter, or becoming too hot during the summer. If you’ve already completed air sealing measures on the building envelope of your home (check our other blog post on this topic), then adding insulation is the next best step to improving your energy efficiency and reducing your monthly utility bill!

Types of insulation

There are a variety of types of insulation that can be used to regulate the flow of heat in or out of your home.

Batt or blanket insulation

The most common form of insulation that comes in thick sheets
Often made of glass fibres or mineral fibres
Easy to install, can be cut to fit most spaces
Should not have any gaps around edges when installing, nor be compressed to fit a space (this will impact insulating ability)

Loose-fill insulation

A good option for filling hard-to-reach areas or uneven spaces
Useful for topping up insulation in attics or enclosed wall cavities
Can be poured or blown into small spaces
Will often settle after installation, which may create a gap at the top of the space you’re trying to fill
Consider hiring a professional contractor to install this kind of insulation using proper techniques
Various materials used for loose-fill insulation includes:
- Cellulose fibre: made from shredded newspaper and is treated for fire-resistance and prevention of fungal growth. This material is good for filling in a space that has wiring or nails, however be aware that it can create a lot of dust when installing! Cellulose fibre can be an environmentally-friendly alternative due to its ability to trap carbon from the atmosphere (GCC, 2023).
- Mineral fibre: this includes mineral wool or rock wool, and is treated with oil to suppress dust. This material is suitable for attic spaces or other inaccessible areas like wood-framed walls, roofs, or floors. Fibres can sometimes irritate your eyes, skin, or airways, so wear protective equipment when handling (GCC, 2023).
- Fibreglass: made using finely-spun glass fibres, and can sometimes be made using recycled glass for added environmental impact (GCC, 2023). Can be used in open horizontal surfaces (like attics), or blown into vertical surfaces (like wall cavities).

Rigid Board Insulation

Are lightweight and easy to cut, although can be difficult to install in irregularly-shaped spaces
Usually more expensive than loose-fill or batt insulation, but has higher insulating value.
Commonly used on exterior walls, as installation on interior walls requires a special fire-resistant covering across the insulation board
Materials used in rigid board insulation includes:
- Expanded polystyrene (EPS): made using plastic beads and steam to create either a high-density or low-density “bead board”.
- Extruded polystyrene (XPS): a board made of foam plastic, with small pockets of air and refrigerant gases. This makes for low permeability of moisture, making this kind of insulating board suitable for walls that are below-grade.
- Mineral fibre: made by compressing mineral fibre insulation with a binder agent to create a semi-rigid insulation board. Suitable as a vertical drainage layer for below-grade exteriors of residential homes.
- Polyurethane: a plastic board with small pockets of refrigerant gases instead of air, and usually has foil on both faces to act as a vapour barrier. Good for smaller spaces that require a higher insulation value, such as basements.
- Polyisocyanurate: a plastic board very similar to polyurethane, however the insulation value for this material drops in colder temperatures, so it should be used in interior insulation.

Spray-foam Insulation

Is a mixture of plastic resin and a catalyst that mixes to create a foam that expands and sets quickly
Can be poured into a cavity, or sprayed onto a building's surface using a spray pump
Important to cover with a fire-resistant material, such as a half-inch inch of drywall
Usually required that the building be vacant for a 24-hour curing period due to fumes from the foam
There are two types of spray foam:
- Closed-cell polyurethane foam: is a high-density foam that is sprayed in 2-inch layers, and can act as a vapour barrier. This type of foam is more expensive, and can only expand up to 35x its initial volume, so is not the best option for enclosed cavities.
- Open-cell polyurethane foam: is a low-density foam that is more spongy, and semi-flexible. This type of foam is more cost effective, and can expand up to 100x its initial volume, so it is a better choice for filling large cavities.

Cementitious Foam Insulation

A chalky-textured foam that is non-combustible and made without plastic
Can be poured into cavities, where it will need time to dry
Best installed by a certified contractor

Reflective bubble foil insulation

A sheet of plastic bubble wrap with a reflective layer of foil attached
Most commonly used in hot environments to reflect solar radiation
Because Canada is a colder climate, this type of insulation may not perform as well

How insulation is rated

Insulation is measured based on how well it can resist the flow of heat. You will see this measurement on insulation materials as an R-value (imperial system) or RSI value (metric system). Essentially, the higher the R-value is, the slower heat will transfer through the material. All homes will have a minimum R-value of insulation installed throughout the home as required by the Ontario Building Code (GNI, 2024). Many energy efficiency rebate and loan programs will require you to increase the R-value of your insulation in various locations throughout your house.

For example, the attic of your home may already have a small amount of insulation with an R-12 value installed, but criteria for the Canada Greener Homes Loan would require an increase in R-value to a maximum of R-50 for your attic insulation.

Some professional insulation contractors will measure insulation as R-value per inch of thickness (R-3.4 to R-3.9 per inch for blown cellulose insulation, for example), until a total R-value is reached based on the depth of insulation (GNI, 2024). The recommended R-value for insulation will change depending on the area of the house you are installing it at. Essentially, choosing insulation with a higher R-value will help improve your overall energy efficiency by reducing the amount of heat leaving or entering your home.

What is embodied carbon?

This is the greenhouse gas (GHG) emissions that are associated with building materials, like insulation. Factors that contribute to the embodied carbon of materials include manufacturing, transportation, installation, and maintenance of the material. You can reduce the carbon footprint of your home by selecting building materials with lower embodied carbon, such as plant-based materials over plastic or mineral-based ones.

Things to consider before installation

Before you install any insulation in your house, be sure to air seal the area to reduce any risk of air leakage! Certain types of insulation have air/vapour barrier qualities, but the effectiveness of any insulation will be reduced if there are persistent gaps in the building envelope that allow for heat to flow in and out. Check out our other blog post of air sealing your home here!

Things to consider during installation

When installing insulation, you’ll want to make sure that you use enough insulating material to fill the entire space evenly. Any gaps in the insulation will allow heat to escape past the insulation – pay attention to corners especially! Also, be mindful of thermal bridging. This happens when heat flows through a structural feature that is connected to both the cold side of the building envelope and the warm side (such as a stud plank within a wall cavity). By covering the thermal bridge area with insulating material (such as a rigid foam board), you’ll ensure the continuity of insulation around the entirety of the house, and reduce the flow of heat in and out of the building.

We are here to help!

Choosing the right insulating material, and making sure it is installed properly, can be complicated. Our Registered Energy Advisors (REAs) at Green Venture are certified by Natural Resources Canada, and can help you decide upon the best insulation options that fit the unique needs of your home through our EnerGuide energy auditing service. Our REAs will help you understand the current energy use of your home, and where you can start making changes to improve your energy efficiency – beyond just upgrading your insulation!

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