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Five Tips for Using Spray Foam Sealant

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Tom Lohr is an avid home DIY enthusiast. He prefers to spend the money he saves on new tools and gardening supplies.

The most frequent brand of foam sealant you will find

The most frequent brand of foam sealant you will find

Those Gaps are Costing You Plenty

A drafty house can be uncomfortable and increase the cost of climate control. Older houses especially, have dozens of places where the outside air is getting in. The biggest of those intrusive air entry spots can be blocked off using portions of a roll of fiberglass insulation. But some of those trouble areas have gaps too small to make stuffing fiberglass insulation feasible. The best option for sealing those drafts is spray foam sealant.

Spray foam is a quick, easy and very efficient way to seal gaps and cracks and a very simple DIY project. It does a great job, in fact, one of the most popular brands is called “Great Stuff.” Cans of sealant are inexpensive, available a most hardware stores, and simple to use if you are armed with a bit of knowledge. Don't let the first time you use a can be a learning experience rather than a successful project. Here are five tips that will make using spray foam sealant a pleasant rather than painful experience.

1. Know What Type You Need

You would think one type of spray foam would be suitable for all of your needs. Normally, one type is all you will need, but know there are some specialty variants available as well. Great Stuff seems to have to most flavors, here is a rundown of the types and uses.

The Normal Type-seals gaps up to 1 inch wide.

Big Gap Filler-seals gaps up to 3 inches wide.

Window and Door-allegedly, normal spray foam produces enough pressure as it expands to knock your door or window out of square. The Window and Door variant does not expand as much.

Pest Block-keep bugs from entering though cracks. It claims to have no pesticide in it, so frankly, I don't know what the difference would be between the Pest Block and normal spray foam would be. Both seal cracks just the same. It might serve to put someone in your household as ease after seeing a huge hairy spider, but other than that, I would use the normal type.

Fire Block-is a fire retardant version of spray foam. This would be useful if you were trying to adhere to strict fire codes. Some walls in your home are supposed to be fire retardant. The walls between your rooms and garage if you have an attached garage for example. Plus, it is bright orange so any inspector knows without a doubt that the sealant meets building code.

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2. Make a Plan

One drawback to canned spray foam is that it is one use only. Once you start spraying, the clock is ticking and the foam will eventually block the applicator tube. It would be a waste to use only 10% of a can for a small crack. Find all of the drafty cracks and gaps in your house and make note of their location. Once you open a can, keep filling those cracks until the can is empty.

Spray foam residue on my hand...24 hours after using it and numerous washings.

Spray foam residue on my hand...24 hours after using it and numerous washings.

3. Wear Gloves

It states on the can to wear gloves. Why should you? It's not really that toxic. But unless you want your hands to look like they were involved in a nuclear accident, use gloves. The spray foam is messy and you WILL get some on your hands. Or like me, get a lot on your hands. If you do, don't worry, it will wear about three days (see photo). There is no washing that stuff off unless you want to douse your hands in solvent, which is not recommended.

4. Observe the Flow of Sealant

Great Stuff claims to have this “quick stop” tip on the applicator that keeps it from flowing out after you have stopped pulling the trigger. While it may be better than nothing at all, it does NOT stop the flow of sealant immediately. The pressure in the applicator tube will force some out after you want to be finished. During the sealing of the first few gaps, take note of how much seeps out after you have stopped pulling the trigger. Adjust your application method for subsequent gaps.

Seal those small, out of the way, drafty gaps.

Seal those small, out of the way, drafty gaps.

5. Wait for Cleanup

Not only will you get some sealant on your hands, you will get some one the floor, window sill and anything else nearby. It will fall off in a glob and land somewhere you did not intend for it to go. Instinct will want you to wipe it up immediately with a rag. Don't. You will get most of it up with a rag, but also leave a smear of sticky substance where you wiped. Instead, wait an hour. Once the foam has cured, use a putty knife or something similar and slide it underneath the wayward pile of foam. It will pop off cleanly with no mess.

Better Living Through Chemistry

Living in the 21st century has its advantages. Cool, space-age products like expanding foam in a can to plug holes is one of them. You have enough projects waiting for you to get to, make sealing up your home less of a hassle and let advanced chemistry work for you. And enjoy the lower energy bill.

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.


Peggy Woods from Houston, Texas on February 13, 2021:

Thanks for all the tips on how to efficiently and safely use this product.

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