Fibreglass or Spray Foam Insulation

Fibreglass or Spray Foam Insulation?

If you need to replace your insulation, you may be unsure whether you should opt for fibreglass or spray foam insulation. Here’s a comparison to help you choose.

The basics

Fibreglass insulation is made up of glass fibres that trap air bubbles, thereby creating an insulating effect by slowing down heat exchange.

Spray foam, on the other hand, is made from a combination of chemicals. When mixed, it foams up and expands considerably(in some cases, up to 100 times its liquid volume). This allows the material to close gaps, even small ones, where air might seep through.

Energy efficiency

One of the most significant differences between fibreglass insulation and spray foam insulation is that the former can sometimes leave gaps around fixtures while the latter won’t. In addition, fibreglass doesn’t prevent air from passing through as effectively as spray foam, meaning it needs an additional air barrier to be as effective.

In terms of R-values (which measure the insulation’s resistance to heat flow), spray foam has an approximate R-value of 6 per inch of thickness, meaning homeowners need around 6.3 inches to reach a baseline value of 38. Fibreglass, on the other hand, has an R-value of 2.2 per inch, meaning a lot more of it is required.


Fibreglass typically comes in batts that need to be cut so they fit perfectly in the space they’re meant to insulate. This means that installing it can be a delicate operation and that any mistake will result in potentially substantial heat transfer. However, such issues are mitigated by hiring a professional who knows what they’re doing.

Spray foam, on the other hand, always needs to be installed by a professional. This is because of the training and knowledge required to mix the liquid that’ll become the foam and to operate the equipment involved.


In terms of outright costs, fibreglass is a lot cheaper than spray foam. However, in the long run, it may be more advantageous to use spray foam, as it’s more energy-efficient, which means you’ll save money on your power bill. In addition, spray foam lasts longer than fibreglass, which means you won’t have to replace it as often.

Insulation installers in Southern Ontario

While spray foam has many advantages over fibreglass, the latter can sometimes be a better choice, depending on a number of factors. To make sure you select the right insulation for your needs, consult the experts at Reitzel Insulation. With over 46 years of experience, you can count on us to provide outstanding service, so contact us today to ask for a quote.


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