Dow Great Stuff Big Gap Filler Product Review

We're in the process of finishing the basement and hired an insulation crew to finish up insulating the large gaps in the basement ceiling. Unfortunately, a wooden beam on a wall we framed in blocks the voids near the ceiling. The insulation team told us we needed to insulate this wall ourselves with spray foam. So off to Home Depot we went, in search of Dow's Great Stuff Big Gap Filler foam insulation.

Thinking we'd need a lot, we purchased an entire pallet of Great Stuff Big Gap Filler (24 cans in total at $5.99 each). The gaps we needed to fill are large and deep (about 1ft x 1ft), plus it would be difficult to get at them, being that we already framed in the wall. Luckily, Dow's Great Stuff Big Gap filler comes with a thin, plastic straw that attaches to the can, allowing me to sneak the straw into the tiny gap between the wood framing and the concrete void needing filling.

Being that I had such a great time using Great Stuff Window and Door (check out my review here), I volunteered to do this project by myself. I threw on a pair of old paint-stained clothing (if you get Great Stuff on your nice clothing, it's impossible to remove. And you won't be thinking it's such Great Stuff anymore) and a pair of deerskin work gloves. The instructions on the Great Stuff Big Gap Filler container urge you to wear eye protection, but I went without because that's how I roll.

Attaching the plastic straw was easy - I simply removed the plastic packaging and screwed on the straw to the top of the can. I gave the can a good shaking for 30 seconds and I was ready to start shootin' up the voids. If you're going to be using a lot of Great Stuff Big Gap filler cans, conserve your straws. When the can is empty, detach the straw and use on your next can. Save the extra straws because they break easily.

Using Great Stuff Big Gap Filler was easy at first. Simply hold down the trigger and let it fly. The insulation looks like cream-colored whip cream. It starts expanding the minute you apply it, and continues expanding for the next hour. The instructions tell you to fill the void less than 50% full, but because I couldn't really see how much I was spraying or how far back the insulation was getting, I used an entire can for each gap. It was probably overkill, but I needed to make sure it would fill up the void. Click on the pictures in the article to see my project!

After going through four cans of Great Stuff Big Gap Filler, my wrists and fingers were tired. When the can is completely full, the trigger is easy to use, but as the can empties, using the plastic straw becomes challenging. Expect sore fingers and wrists for a few days!

Plan on using up an entire can in one use. Although the package claims it can be used multiple times, it's unnerving trying to unclog the nozzle. You can use a hammer and a nail to reopen the nozzle, but sometimes it doesn't work. It's best to use up the can, take a break, and start fresh with a new Great Stuff Big Gap Filler can.

Great Stuff Big Gap Filler claims to have 3 times the expanding power than the original Great Stuff, and we did find this to be true. After 8 hours, we checked the cracks and everything was looking good. Because I used up an entire can of Great Stuff Big Gap Filler on each void, we have cream-looking bulbous lumps seeping out, but once it has fully cured (8 hours), it can be trimmed.

Clean up was pretty simple. You're going to get some Great Stuff droppings on the floor, so make sure to cover in newspapers. For me, I was working over a concrete, unfinished basement floor, so it didn't really matter if I made a mess. To clean up, I waited until the Great Stuff insulation was tact free (10 minutes) and picked up the foam off the floor.

Great Stuff Big Gap Filler definitely lives up to its name. It expands 3 times more than the other products in the Great Stuff line and with the thin straw, you can sneak Great Stuff insulation up into hard-to-reach areas. Just remember to wear old clothing!