Is Attic Ventilation Necessary With Spray Foam Insulation?

Ventilation is essential when using traditional insulation in an attic. A home’s attic that isn’t adequately insulated will draw heat and air conditioning out of the building, resulting in moisture that leads to mould development, as well as causing roof damage. Rather than fibreglass or cellulose, you can use spray foam to create a sealed attic area.

When you combine isocyanate and polyol resin, you get basic spray foam. This results in polyurethane. Spray foam insulation has been utilized in homes since the 1970s. 

There are two kinds of spray forms, as follows:

  • Open-Cell Spray Foam: allows air into the cells, making the foam less dense and softer
  • Closed-Cell Spray Foam: the finest insulator and produces an air seal

Why Spray Foam Insulation Does Not Need Attic Ventilation

There are two reasons why spray foam doesn’t need attic ventilation. The first reason is because of how spray foam insulation works. The second reason is that conventional insulation doesn’t need attic ventilation either.

Spray foam insulation doesn’t need attic ventilation because it seals up the attic’s air movement. The spray foam insulation seals the entire attic off from the rest of the house. As long as the home’s HVAC system pulls the right amount of warm air into the attic during the winter and the right amount of cool air into the attic during the summer, the spray-foamed attic will not need any additional ventilation.

Attic ventilation for cellulose and fibreglass insulation is also unnecessary, but for a different reason. These types of attic insulation are both causes of moisture buildup in the attic. They also prevent air from circulating in the attic, encouraging mould growth.

However, spray foam insulation seals these problems from occurring in the first place. Therefore, spray foam insulation is the only proper solution to these issues associated with traditional attic insulation.

Notice that there is no air in the attic when spray foam insulation is used. This is a good thing; contact with air can cause premature deterioration of the roofing materials.

How Moisture and Ventilation Affect Insulation

While spray foam insulation does not need attic ventilation, the attic will still need adequate ventilation. If you live in a hot area, you should have a fan in the attic to help provide airflow. You don’t need a fan if you live in a cooler place, but you can certainly add one.

Another advantage to using spray foam insulation is its R-value. Most spray foam insulation products have an R-value of 6-15, which is the best you can get out of the insulation. While some types of spray foam are more expensive, some types are very affordable. 

Spray foam insulation works well in basements, attics, and crawl spaces because it is a 100 percent air-sealer. The spray foam will not allow any leaks, resulting in moisture buildup and mould growth.

Fibreglass and cellulose are both organic products that are not made to be waterproof, which means they absorb water. Once the insulation absorbs water, it will rot because the insulation’s paper breaks down. This eventually invites mould growth and other potential structural issues.

On the other hand, spray foam is waterproof, and it does not absorb water at all. Once spray foam is installed in the attic, it will never break down or rot, eliminating the need for any future repairs.


Spray foam insulation is the best insulation you can use in your attic. It is a 100 percent air-sealer. It does not break down or rot and does not absorb water. 

Spray foam insulation will save you money because you won’t worry about roof repairs or replacing your attic’s insulation. Cut back on your energy bills by using spray foam insulation, and stop worrying about the moisture and mould issues that come with fibreglass and cellulose insulation.

Are you looking for Toronto’s best foam insulation contractor? Foamworks is a renowned insulation contractor specializing in installing high-quality spray foam insulation. Spray foam is usually regarded as the best insulation solution for residential and commercial construction. Give us a call now to know more about our services.

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