How To Use Expanding Foam Spray

Expanding foam is a substance used to fill gaps. While there are many problems that you need to contact a specialist to solve, others need nothing more than expanding foam. 

expanding foam

Expanding foam is a revolutionary item that can be used by anyone. It has many, many purposes, but just like with anything involving chemicals, it’s important that the proper precautions are taken.

What Is Expanding Foam Spray?

Expanding foam is designed to apply as a liquid and expand as it dries expanding tens or hundreds of times its original size. They come in many different shapes and sizes but they are generally found in canisters with spray nozzles.

This makes it easy to apply the expanding foam spray anywhere because the nozzle is very small like a coffee stirrer/straw. Expanding foam is a wonderful invention that has helped contractors and DIYers everywhere for decades. 

The foam was invented by Walter Baughman in 1953 and was called the “Blendometer” to be used by homeowners. Today, the application is easy and has been since the 1980s when the modern-day spray nozzle was first used. 

Types Of Expanding Foam

Types Of Expanding Foam

Most expanding foams are fairly similar with one thing keeping them separate. This would be just how much they expand when they dry. Here are the three main types of expanding spray foam available. 


High-density spray foam is strong and dense. It is great for sealing roofs to keep water and air out. Plus, it works great outdoors and is weatherproof, which can’t be said for lighter densities of spray foam. 

It can also work as a layer of insulation that is thin rather than thick. This type of expanding foam is the heaviest once it is cured weighing pounds per cubic foot whereas the lighter ones weigh two pounds or less. 


The medium-density foam also makes a good vapor barrier. It is a great option if you’re not sure what to get because it is dense but expands quite a bit. It is the most common type of spray foam for crawlspaces. 

Medium-density spray foam is very strong because it isn’t too dense so it won’t crack but it isn’t too spongey so it’s unlikely to tear. This is always a safe bet which is why it is so popular. You can’t go wrong with it.


Low-density spray foam is good for blocking out air but not moisture. That’s because it is a spongey foam that expands a lot yet is low-density. There are bubbles inside of the foam that keep it very light. 

Because it is so lightweight and airy, it does a great job at filling open spaces and can work as an insulator. Denser foams are too heavy for this so you can see that every type of expanding foam is needed. 

What To Do With Expanding Foam Tips

Expanding Foam Spray

Learning what to do and what not to do with spray foam is crucial if you plan on using it. Here are the things you can do with spray foam and some tips that can help you do things the right way from the start.

Ensure It Is Good

Even though it doesn’t seem like it, expanding foam is like food. Not that it is edible, but because it expires too. There should be an expiration date on the bottom of the canister that lets you know when to toss it.

Check the expanding foam before you buy it to make sure that it is good for a long while. Then, if you store some, check it every time before you open it. If the foam has expired, go ahead and dispose of it properly. 

Cut Or Dissolve Excess

There are two ways to get rid of the excess spray foam but you should only do so after it dries. If you dry to do so while it is drying, it will peel and make a mess, like wiping up syrup and toothpaste mixed. 

Instead, wait until it dries and either cut the excess off with a utility knife or use a solvent. You can buy one especially for this purpose or use something like nail polish remover, aka acetone which is very strong. 

Stabilize Faucets

You can use spray foam around faucets and showerheads to stabilize them. If there is a noticeable gap, start there and remember to cut off the excess. If there isn’t, then you can open the cabinet or wall and apply it there. 

You shouldn’t need much either way. After all, you don’t want to overdo it and make a mess. You just need enough to fill any gaps and sort of tack what is there so it won’t wiggle or leak when water runs down it

Insulate Plumbing 

Expanding Foam Spray

You can definitely use expanding foam to insulate plumbing, unlike with wiring. Because the pipes won’t be disturbed by the foam, you can spray it around the pipes and it can actually be beneficial. 

Insulating your pipes with expanding foam can help prevent water from freezing. That’s one of the reasons that expanding foam is used in crawlspaces so often. It is a wonderful insulator and is safe to use.

Dampen Area

Dampen the area before you start and after. Don’t oversaturate it, but make sure that it is slightly damp to make the process go smoother. The foam will dry faster if the area you are spraying is slightly damp. 

Use A Gun

A spray foam gun, of course. You can buy spray foam guns that are reusable and they make a huge difference. There are manual ones and automatic ones and both of them work amazingly well to speed up the job.

They aren’t necessary but they come with attachments and make things go faster. They are also reusable so you can buy cartridges over the years and as long as you keep your gun clean, you can reuse it.

Protect Yourself

Wear a mask and gloves whenever you use spray foam. It is surprisingly strong, especially certain brands and high-density foams. The gloves will protect you from rashes, caked-on foam, and infections. 

It’s a good idea to wear disposable gloves and masks as well because any foam that gets on them will be difficult to get off. So wear something that you are okay with tossing if they get ruined in the process. 

Keep Pests Out

Expanding foam is penetrable but it’s unlikely that any insects or rodents will get through it. It is possible for rodents to get through but it is very unlikely that any insects will make it through. But keep an eye out just in case. 

What Not To Do With Expanding Foam Tips

What Not To Do With Expanding Foam

Learning what not to do is just as important as learning what to do. These are expanding foam tips regarding things that you definitely don’t want to do. Be careful and listen to these warnings for your own safety. 

Use Expanding Foam Around Heat

Never use expanding foam around an open flame and be careful when you use it around any sort of heat. It is highly flammable, so use it with caution. If using around a fireplace, make sure you don’t have a fire going.

When storing the canister, store them in a cool, dry place. Never store them in extremely hot weather, store them indoors if it is too hot outside because you risk the can exploding and injuring someone. 

Use Expanding Foam Around Wiring

Don’t use expanding foam around wiring. This isn’t a good idea for a few reasons. The main reason is that it can get in the way. Electronic devices and electrical wires may need to be repaired and foam is difficult to remove.

But another reason is that it can actually harm the wires. The foam expands and when it does, it can pull the wires apart. This not only makes wiring difficult to repair but it causes problems that need to be repaired. 

Overuse Expanding Foam Around Windows 

You can use expanding foam around windows but you need to be careful. Don’t use foam that expands too much or else it can actually break the original seal of the window and compromise the integrity.

For large gaps, it can help close them, but for smaller gaps, caulk is a better option. Learn about sealing and weatherproofing windows before you start using spray foam to find out if it is a good option. 

Apply Expanding Foam To Paneling Or Wallpaper

There are many materials that spray foam won’t harm, but those with a printed top or a paper layer may peel when the spray foam dries. If it doesn’t peel, it will have spray foam stuck on on that will be very stubborn. 

Substitute Expanding Foam With Caulk

A lot of people assume that caulk and spray foam is the same. But they are far from identical. You shouldn’t substitute one for the other. Instead, learn what each of them is for and only use them accordingly.

Caulk doesn’t expand or at least does very little at times. It is waterproof and is perfect for sealing bathrooms and more. Spray foam on the other hand fills larger gaps and expands for a tight, sticky seal.

Neglect Expansion of Expanding Foam

Never neglect to inform yourself on how much the spray foam will expand. Every spray foam expands but they don’t all expand the same amount. So make sure you know how much yours will expand before you start.

This is one of the first things you do! Read the canisters before you begin your project to find out the best spray foam for the job. It can be such a usfeul substance once you learn just how to use it properly.