The DOs & DON’Ts of DIY Spray Foam Insulation

I’ve come across spray foam insulation being used by many DIYers in just about every way imaginable BUT just because you can use it for a variety of purposes, it doesn’t necessarily mean that you should! Today I’m going to share with you the ways that I use spray foam insulation in my remodeling projects and some applications where I don’t recommend it, or think a better solution is required. 

This project contains a paid product integration from Loctite and affiliate links to the The Home Depot. All opinions are herein are my own. Visit my disclosure page for more information on affiliate and compensation this site accepts. 

DO: Use Window & Door Foam to Seal Around Rough Openings

Whenever I’m installing windows and doors, the rough openings are always slightly larger than the window or door itself. That means you’re always left with a small gap that can create drafts, air loss, or be an avenue for pests to find their way in. In this case, you should definitely use the window and door spray foam. The window and door foam expands at low pressure compared to other types so you won’t risk bending or bowing the door or window jambs causing problems with their operation. 

DON’T: Use to Address Structural Cracks in Foundations or Concrete

Next, let’s talk about cracks. Not all cracks are created equal. For example, if I come across a crack in a foundation, spray foam insulation wouldn’t be my go-to fix. Foundation cracks can be superficial, or they may be structural so understanding the problem is essential to creating the right fix. I would never use spray foam to address a structural problem like a foundation crack. The same goes for most cracks in concrete including sidewalks, driveways, patios, etc. 

DO: Use to Air Seal Attics & Crawlspaces

One of the best uses for spray foam applications is to use it for air sealing. When I recently replaced the insulation in my attic, I first went through and sealed all the visible cracks and penetrations I could see in the attic before adding the blown in insulation on top. Filling any voids with spray foam makes sure you have a tight envelope between your living space and the attic. I climbed around in the dark in my attic and looked for light leaks from below and filled those areas. The same can be said for crawl spaces beneath the house that can be spots where air loss occurs. 

DON’T: Use to Address Issues with Improper Framing or as a Wood Substitute 

One of the biggest no-no’s I have seen from DIYers is using spray foam to fill structural gaps in framing. I’ve opened some walls and found that people sometimes will mis-cut a piece of lumber and rather than recutting it the proper size, they just slap it in place and fill the gap with spray foam. You might be surprised how often this happens especially in DIY flip houses. Just because something looks decent on the outside doesn’t always mean it looks great underneath. Don’t use spray foam to fill any structural gaps as it’s not a structurally rated product. 

DO: Use On Small Penetrations to Seal Out Insects and Pests

I have a really old house so there are a lot of unseen areas where there are small holes or cracks. I typically find them after I have some unwanted visitors in the house. Probably my favorite application for spray foam is to fill those areas to seal out ants, spiders, and other insects. Typically with ants I can follow their trail to see where they are coming in from outside and then use spray foam to fill those areas. Now if the hole or penetration is larger, like something a mouse or a rat can get through, I don’t recommend using spray foam UNLESS you add some wire mesh to the area first. Larger pests like that can sometimes chew their way through the foam and get back in. 

DON’T: Use to Fill In Eave & Soffit Areas that Effect Attic Ventilation

Another area to be careful of is using spray foam in eaves and soffits. These are common trouble areas for bees nests and many homeowners elect to spray foam to seal out the bees. However, you always want to be careful that you’re not interfering with your home’s ability to breathe properly. Some homes have vented eaves and soffits that allow your attic to vent properly and by filling in these areas, your attic space can’t vent properly. If it’s one trouble spot it’s not a big deal but be conscious if you find yourself sealing larger areas. 

DO: Use to Seal Around Electrical and Plumbing Penetrations (Code Permitting)

Electrical and plumbing penetrations into a home is another great use for spray foam. However, it’s important to make sure a fire rated foam isn’t required by code in your area. I always like to seal around exterior electrical boxes and any plumbing pipe penetrations around the perimeter of my house because these are really common points of drafts as well as can act as super highways for critters coming in and out of your house. 

DON’T: Use to Seal Water Leaks in Plumbing

Another huge fail for spray foam is people using it to try and stop leaks. Rather than fixing the underlying issue, I have seen some homes where people have attempted to stop a leak from a pipe or water line with spray foam. Please don’t use spray foam for this. Most of the time all it does is create a larger issue down the road. It won’t solve the problem and will most likely result in larger damage taking place once the water finds a way out. Depending on the application, the foam can actually allow the water to build up which can lead to serious mold problems so do yourself a favor and if you’re experiencing any kind of water leak, avoid using spray foam as a bandaid. 

DO: Use in Moderation! 

My last tip is just that use spray foam in MODERATION. People have a tendency to spray things and trying to find extra uses for it and end up using the whole can before the nozzle gets all plugged up and they can’t use the can anymore. Trust me, I know that can be frustrating. BUT here’s what I would recommend instead. Use the can in moderation and only use as much as you need. Remember that these products expand somewhat exponentially. As far as reusing the can, I recommend that you just buy a bunch of extra straws. You can snag a whole pack online for just a few $$ and keeps you from wasting a bunch of money on new cans. 

So that’s it for this article! If enjoyed it, please consider subscribing to my YouTube channel so you never miss out on any of the new content I post. 

Thank you to Loctite for making this video possible and allowing me to share how to properly use spray foam. If you guys do need some spray foam for your next project, I encourage you to check out their products which you can find at your local Home Depot

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