blow-in attic insulation toronto

How Much Attic Insulation is Recommended in Ontario

The effectiveness of insulation is measured in relation to its thermal resistance which is a way of saying how much conductive heat flow the product stops from going through it. This measurement is described as R-Value. Generally speaking, a higher R-value means better insulating properties. The recommended R-value for attic insulation in Ontario is between R-50 and R-60.

R-Values of Common Types of Insulation

The two distinct types of attic insulation are loose-fill material (also commonly known as blown in insulation) and batting. The R-Value of the insulation for every inch of thickness depends on the type of insulation. As a general guide from the Department of Energy, the R-Values for the most common types of insulation per inch are;

Loose-fill Cellulose 3.1 – 3.8
Loose-fill Fiberglass 2.2 – 2.9
Loose-fill Stone Wool 2.2 – 3.3
Fiberglass Batting 2.9 – 3.8
Stone Wool Batting 3.3 – 4.2
Polyurethane Foam 5.6 – 8.0
Cementiotious Foam 2.0 – 3.9

These values are a rough guide as the true R-Value of the insulation depends on more factors than the indicated R-Value as explored in detail below.

Recommended R Value for Attic Insulation Canada 

The recommended R value for insulation of attics in Canada depends on the area, as it is a value that changes a lot from area to area. The province, the city and the area greatly influence the difference in R Value for the insulation of an attic. It must be considered, then, that the minimum thermal resistance of the attic, or any other area of the house, is a requirement that must be respected by law (National Bulding Code or the building codes of the different provincies)

Here is a precise list of the R-Values ​​necessary for the insulation of roofs in Canada, with related types of better insulation. The R Value is increasing, so the higher it is, the more thermally insulated your home will be.

British Columbia:

  • Zone 4 and Zone 5: R-Value recommended from R40 to R60, with Batt or Blown Insulation.
  • Zone 6 and Zone 7A:R-Value recommended from R50 to R60, with Batt or Blown Insulation.


  • R-Value recommended from R31 to R60, with Batt or Blown Insulation.


  • Zone 7A and Zone 7B: R-Value recommended from R50 to R60, with Batt or Blown Insulation.


  • Zone 7A and Zone 7B: R-Value recommended from R50 to R60, with Batt or Blown Insulation.


  • Zone 1 and Zone 2: R-Value recommended from R60 to R80.


  • Zone 1: R-Value recommendend from R41 to R60, with Batt or Blown Insulation.
  • Zone 2: R-Value recommendend from R51 to R60, with Batt or Blown Insulation.

Atlantic Canada:

  • Zone 5 and Zone 6: R-Value recommendend from R50 to R60, with Batt or Blown Insulation.
  • Zone 7A: R-Value recommendend is R60, with Batt or Blown Insulation.

 Attic Insulation R Value Ontario  

Now, let’s go deeper into the R-Value in Ontario, which you must take into account if you want to insulate a roof (but also the rest of your home). The first thing to know is that the areas of Ontario are the ones where you will need the highest R Value to be able to optimally insulate your attic.

Always keep in mind, when you go to carry out this type of insulation work, that you must carry out the work according to Ontario Building Code. The Ontario Building Code, in fact, is the legislative reference for Ontario also in terms of insulation, both in terms of limits and in terms of safety.

Here is a list of R values to insulate an attic in Ontario.

Ontario Zone 1 and Ontario Zone 2

The level of R Value required for insulation and the type of insulation recommended for the two areas of Ontario are the same. There are internal changes, due to the presence or absence of the attic.

In the event that your ceiling has an attic, the insulation must be greater:

  • Good Insulation: R-60, with Batt or Blown Insulation
  • Better Insulation: R-70, with Batt or Blown Insulation
  • Best Insulation: R-80, with Batt or Blown Insulation

All the requirements on this list exceed the minimum requirements of the Supplementary Standard SB-12 of the 2017 Ontario Building Code. In any case, before starting to build a building or insulating an attic it is always better to have the local building department check and validate the thermal resistance.

 Ontario Building Code Insulation 2019

The Ontario Builnding Code changed in 2019 regarding isolation. With precision, there has been a change in the insulation requirements: continuous insulation and attic insulation.

The rules and code updates occur every few years, so that the Ontario Building Code is updated by also integrating new discoveries and technology in the field of construction and insulation. In this case, the additions of 2019 related to energy saving initiatives for insulation in new homes or additional insulation.

Here are the two main changes:

  • Continuus Insulation: It consists in insulating every corner of a house to eliminate all possible thermal bridges without leaving even a crack, creating an insulating armor around the house. Thermal bridges are those points in the house that allow passage and heat loss, and can be anywhere. An example would be to insulate with rigid board stock in the basement, so as not to leave uncovered points and the possibility of thermal bridges. In these cases, the best thing is to call an expert, have the house studied from top to bottom and decide what to do.
  • Attic Insulation: The change that occurred in the attic insulation in the Ontario building code was in the minimum required R value. The recommended R Value has been raised from R 50 to R 60 in order to increase the insulation of the attics.

These are changes made in order to increase the energy efficiency of the home and thus also save energy. In any case, a standard package of improvements can be applied to meet the new standard. Some of the changes that can be made are: Insulate, or better insulate, the attic to increase the R Value; install an HRV (a system for recovering energy from ventilation systems); apply continuous insulation to the home or install a drain heat recovery unit.

 Ontario Building Code Insulation

The Ontario Building Code Insulation Section was created specifically to avoid unsafe construction practices, materials and construction methods. It serves to guarantee both homeowners and builders safe and comfortable homes.

First, the section of the law that concerns insulation requires that each section of a house that separates the inside from the outside, and vice versa, must have:

  • Insulation (or a thermal barrier).
  • An air barrier.
  • A vapour retarder.

Obviously, each of these sections is thorough and everything is explained with extreme precision. For example, the internal walls of a house must prevent condensation from forming in winter.

The code also specifies which materials to use for insulation and how to install them. All materials, therefore, must meet the established requirements, which material manufacturers are concerned with even before the insulation materials are marketed. Consequently, never use second-hand materials or materials of dubious origin.

The section of the Ontario Building Code regarding insulation, then, deals in depth with the two main types of insulation, regulating them. Here are some of the rules regarding the installation of thermal insulation and the installation of Loose-Fill Insulation:

  • Installation of Thermal Insulation: The insulation must be in contact with an air barrier in order to prevent the flow of air through the material from being compromised; in case the insulating material is vulnerable to water, then it must be at least at a height of 2” above a crawl space floor; if the insulation is exposed to atmospheric events, it must be protected by 6mm thick preservative plywood or 12mm cement parging.
  • Installation of Loose-Fill Insulation: It must not be moved after installation; it must be covered by a membrane through which you can look; it must not swell and interfere with the internal finishes of the home.

 Attic Insulation R-value

The insulation levels of an attic, or of any part of a house, are understood through the R Value, that is the value with which the insulating material is resistant to heat flow. In general, to optimally isolate an attic, on average, an R value of the insulation is required, ranging from R 50 to R 60.

However, this value varies not only on the basis of the type of insulating material, but also on the area: the further north-northeast you go, the colder it is and the more necessary R value will grow.

In case you already have an isolated attic, but you don’t know the R Value, you can do a quick calculation by looking at the type of insulation:

  • Fiberglass: Usually with the appearance of loose fibers with a light-weight yellow, pink, or white color. To calculate the R-Value, roughly, the calculation is (2.5 * insulation depth). If the fiberglass is in batts, the calculation is (3.2 * insulation depth)
  • Rock Wool: It looks like real wool, usually black, yellow or gray. To calculate the R-Value, roughly, the calculation is (2.8 * insulation depth).
  • Cellulose: It looks like small gray flat pieces or fibers. To calculate the R-Value, roughly, the calculation is (3.7 * insulation depth).
  • Vermiculite and Perlite: It is in granules.To calculate the R-Value, roughly, the calculation is (2.7 * insulation depth).

In any case, these are rough calculations also on how you can collect data or recognize the insulation. If you want to isolate your home or check its level of insulation, the best thing to do is to call a professional is to find out the R value necessary for the insulation of your attic.

cellulose insulation

Recommended Attic Insulation Thickness

The thickness of the insulation of an attic varies according to two main factors: the R Value and the material used as insulation. This is because, as far as materials are concerned, they can be used more or less depending on the insulating power and I can occupy more or less space. As for the R Value, however, the higher it is, the more insulation material will be needed and, consequently, the insulation will be thicker.

Usually, the recommended R Value for attics varies between R 40 and R 80, depending on the area, province and climate. Consequently, the thickness, which fluctuates according to the type of insulating material, must be suitable to meet the needs of R Value. Here is the recommended thickness for the insulation of the penthouses based on the R Value:

  • R 40: Thickness that oscillates between 13 and 15 inches.
  • R 50: Thickness that oscillates between 15 and 19 inches.
  • R 60: Thickness that oscillates between 19 and 22 inches.
  • R 70: Thickness that oscillates between 22 and 25 inches.
  • R 80: Thickness that oscillates between 25 and 28 inches.

The calculation is made considering the most common insulating materials, namely cellulose, mineral wool and glass fiber. Using this material for insulation the thickness is usually one inch for each R 3 of R Value. The oscillation of value, on the other hand, is due to the possible use not so much of other materials, but of different shapes of the various insulating materials used usually.

Factors Affecting Insulation R-Value

Just because the insulation says its R-60 doesn’t necessarily mean that’s what you are going to get once it is installed. There is a distinction to make between nominal R-Value which is the advertised value on the product packaging and the Effective R-Value which is the actual performance of the product as measured in real life conditions. Factors that influence exactly how the attic insulation performs other than the indicated R-Value include;

Brand Name

Like most other products on the market, the insulation brand name matters. Go for known brands that have a proven track record of good performance and purchase from a reputable dealer. If you have no idea where to begin, consult an expert who can give you enough information to make an informed decision. Additionally, look out for third-party certification such as GreenGuard, EcoLogo, SCS Certified and CCMC especially when buying specialized products such as sustainable or eco-friendly insulation. This independent certification adds credibility which is essential if you are paying higher than normal prices for specialized insulation.


There is a lot more work that goes into installing attic insulation than simply laying the batting or blowing the loose-fill material into place. Most of these considerations require specialized knowledge and experience which is why it is impossible to replicate the effectiveness of professionally installed insulation when attempting to do it yourself. There are also additions such as air barriers, thermal bridges, vapour retarders and much more which help the insulation to work at its most efficient.

Attic Flaws

Closely related to the previous point, attic flaws such as under-insulted vent pipes and ducts, under-ventilated attic, architectural flaws, moisture issues, awkward fixtures and air leaks among others all have to be addressed before installing the insulation. The effectiveness of the insulation can be cut drastically with even one of these flaws regardless of the quality, brand or R-Value you are installing.

Attic Insulation Toronto has decades of experience working around these issues and more to make sure that you are getting the best in energy efficiency, soundproofing and ambient temperature advantages from your new insulation.

Density and Thickness

The actual thickness of the insulation isn’t the only consideration when measure R-Value so thick insulation doesn’t always translate to the most effective. There is also the issue of settling particularly with blown-in insulation where the material shifts and settle over time, reducing its R-Value. This problem is easy to overcome by over-insulating but it is not always obvious how much more insulation you need in this case. There might also be space and architectural constraints to overcome which will largely influence the density and thickness you choose to install.

Hire an Expert to Install Attic Insulation in Ontario

Although the recommended R-value for attic insulation is Ontario is straightforward at between R-50 to R-60, there are too many factors at play to make this a DIY project that you can do properly without the relevant training, certification and experience.

Call Attic Insulation Toronto for professional guidance every step of the way from inspection, choosing the right insulation, insulation and assessing to confirm that the new insulation is performing as expected. The savings you make in lower energy bills alone more than pay for the cost of having your insulation installed professionally. 647-931-6385

Article Updated: January 27, 2020