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What is the Best Insulation Around Windows? (Spray Foam vs Fiberglass)

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What is the Best Insulation Around Windows? (Spray Foam vs Fiberglass) Blog Feature
Amanda Ringler

By: Amanda Ringler on December 9th, 2020

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The drafts coming in around your windows is annoying, so now you’re looking for the best insulation to install around them.

The best insulation for stopping drafts around windows will be a material that keeps air from leaking around the frame. The most commonly used insulation materials are fiberglass and window spray foam insulation.

Adding the best insulation around your windows will help make your home more comfortable and save you money on monthly energy bills.

RetroFoam of Michigan has been helping homeowners solve their comfort and energy efficiency problems since 2002. While we install high-pressure spray foam in other areas in the home, we understand what insulation will be best to stop those drafts.

In our continued efforts to educate homeowners, we will discuss fiberglass and window foam insulation and which of the two is the best insulation around windows.

Spray Foam vs Fiberglass Insulation Around Windows

There are a couple of things you need to keep in mind when insulating around your windows – the ease of installation and stopping those drafts.

Let’s take a look at window insulation foam and fiberglass, how they are installed, and how they work.

Fiberglass Window Insulation

Fiberglass insulation is made of plastic reinforced by tiny glass fibers, which gives the plastic additional strength while improving its insulation capacity.

For small projects, like windows, you can get small rolls of the material.

While fiberglass is inexpensive and can be a do-it-yourself project, you have to be really careful when handling the material. The small glass particles can lodge in the skin, be inhaled causing respiratory problems, and can trap allergens from outdoors.

Fiberglass also still allows for air movement through it and won’t create an air barrier, according to Fine Home Building.

To install the fiberglass around your windows, you will need to remove the frame around the window. The fiberglass will need to be cut so it fits snuggly in these spaces without wadding it up. It might seem easier just to cram the fiberglass in this small cavity, but this can actually lead to pockets of air that will allow for a bunch of air leakage. If the fiberglass isn’t installed properly, it will not work as well insulating around your windows.

Window Insulation Foam

Window insulation foam is a low-expanding, low-pressure polyurethane spray foam that is designed to create a weather-tight seal around windows and doors when installed properly.

It can be purchased from any home improvement store and comes in a can.

The canned foam is great to create the air seal you are looking for around your window, but you need to install it correctly.

The installation process is similar to fiberglass – you can remove the frame around the window or the entire window.

Because canned foam has a low-expansion rate and is low-pressure, you will want to ensure you are filling the entire cavity around the window, so you don’t have any leaks. This could take a couple of passes with the can hose.

The Best Window Insulation

Neither material is terribly expensive and can be done as a DIY project, so it comes down to what you decide is the best fit for your home.

Fiberglass will still allow for air movement through it, leaving you with the same drafts and issues you were having before adding the new insulation.

If you want to stop those leaks around your windows completely, you’ll need a material that creates an air seal.

That material is spray foam insulation.

If you want to learn more about the benefits of foam insulation for the rest of your home, check out the Learning Center on our website.

Related Articles

New Windows or New Insulation: What is the Best for Energy Efficiency?

How to Fix Drafty Windows by Sealing and Insulating Around a Window Frame

What is Window Insulation Foam? (Types/Manufacturers/Cost)

Foam Insulation Learning Center

About Amanda Ringler

Amanda previously has worked as a breaking news and crime reporter, TV news producer, and editor in Flint and Detroit. Throughout her career as a journalist, she has won several awards from The Society of Professional Journalists - Detroit Chapter and the Michigan Press Association. As part of the RetroFoam of Michigan family, Amanda uses her experience as a journalist to write content that will help educate homeowners on the benefits of foam insulation. When Amanda isn’t writing, she’s spending time with her husband and rescued huskies. She also loves knitting, making art, cooking, and hosting dinner and a movie night for friends and family.