Great Stuff Spray Foam
By J.R. Bluett
Unless you’re a racing fan with really great vision, you probably haven’t seen this miracle in a can. Great Stuff spray foam expands as it cures — and, when cured, it’s tough, weatherproof, and bugproof. You can fill foundation cracks in old houses with this stuff, or just about any crack or crevice that needs filling. Just keep it in the back of your mind; you’ll know when you need it.
A 12oz. can runs about $5, and a 20oz. can goes for $8.
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May 29th, 2008 at 1:32 pm
Ugh, I hate this stuff. The preivous owner of my house decided that instead of actualy fixing the leak in teh roof, they would jsut spray Great Stuff into the cieling until it stopped dripping. This caused the water to run down the inside of the wall instead, rotting out the roof, and the studs. Far more work than if they had jsut replaced the flashing on the roof in the first place.
May 29th, 2008 at 1:46 pm
I also hate this stuff… much more into the newer latex foam. Doesn’t get stuck on everything, including my fingers for days afterwards.
May 29th, 2008 at 2:24 pm
I like it, but you have to use it in the right places — and using it to patch a hole in a roof isn’t one of them. I’ve used it for exterior cracks and penetrations that are too big for just caulk, and for insulation in a pinch after a raccoon ripped into part of a soffit. Sprayed Great Stuff into the hole, then patched it with a proper bit of plywood.
The big advantage over the latex foam (e.g. — DAP) is that it’s fine to use outside, even if you don’t paint it. The latex stuff just degrades too quickly under UV exposure. The traditional Great Stuff is also very expansive (1:6 ratio IIRC, meaning you spray 1/6 as much in a gap as you think you’ll need).
The downsides, however, are aplenty — it’s incredibly sticky when drying and is nigh impossible to get off anything it touches (wear gloves; ones you don’t care about… you will be tossing them). The cans are pretty much single usage — use it all when you open one, since the stuff will cure in the nozzle and render the remainder inaccessible. They used to sell “small project” versions, but I haven’t seen them in awhile. If you overspray it (see above about expansiveness) then it can break things — it is going to expand, and if a window or door frame is in the way, then they’ll simply have to break. Really.
Small spray foams, whether Great Stuff or latex based, rock for a lot of jobs though, particularly insulating. They dry fast, and when dry the excess can be trimmed off with a utility knife, and they can be painted over. Keep both around and use appropriately.
May 29th, 2008 at 3:12 pm
Zathrus: Good bunch of info; thanks.
May 29th, 2008 at 3:28 pm
If you are interested in this or any Dow Chemical product then this is the time to stock up. Dow Chemical is raising prices of all products by up to 20% starting about now.
May 29th, 2008 at 5:04 pm
When I am done applying the foam I remove the applicator straw and swish it and the top of the can in a shallow pan filled with acetone. Do this before the foam cures and you will be able to use the can as many times as you need to until you empty the can.
May 29th, 2008 at 5:36 pm
Stuff is great… but it def needs to be used for what it was designed. It is great for window installation, or window retrofits, Use it when you switch your old home ” Balance ” weight type system. Use it to fill those old gaps left where the weight shaft was.
but VERY STICKY………..
May 29th, 2008 at 7:44 pm
I used to have a 68 skylark that had lost its quarter panels about half-way up the side to rust and when I drove down gravel roads the car would fill with dust through these gaping holes. I bought a case of great stuff and filled the entire trunk and shaved the excess with a ginsu knife to match the body lines of the car then primered it. The next day I figured that was a waste of space so I cut a good sized divot into the foam and drilled a hole through it and the floor of the trunk. BEST BEER COOLER EVER. You could fill it with ice and just let it melt and drain out the hole.
Hey, I was in High school and the car cost $200 dollars (and was worth about that much as well).
May 30th, 2008 at 5:26 am
I’ve used it in making a waterfall for a pond. Use it to “attach” the flat stones to the liner and to each other. It helps the direct the water to go where you want it to go.
May 30th, 2008 at 7:48 am
I’m gonna agree with Zathrus, buy the smallest can you can find for the job. Anything else is going to end up wasted (unless you enjoy puncturing cans and watching them grow like B movie monsters).
May 30th, 2008 at 7:52 am
I wish they sold it in smaller cans. For small projects I never need a full can and it is a waste at $8 a can to use 10% of it.
I have found you can usually store and reuse the can for up to a month before it just solidifies in the can. I just detach the nozzle and spray it out with compressed air.
May 30th, 2008 at 1:28 pm
According to Dow’s website Great Stuff is available in 6 oz. cans. I haven’t had much luck finding anybody who actually sells it, though.
Also, if you’re worried about over-expansion pushing jambs out then you can use the low-expanding “Windows and Doors” formula.
I use Great Stuff in combination with so-called “hydraulic” cement to fill old service entrances and other holes in the foundation of my old house.
May 31st, 2008 at 6:10 am
Had some work done on my garage that required the use of this stuff. It worked as advertised, but there’s no doubt where I applied it! Next time, I’ll remember a little goes a long way.
June 2nd, 2008 at 6:54 am
Just for the record, this Stuff might be Great, but it is also astoundingly toxic! Isocyanates, yum!
However, there are some projects where nothing else will do. I used to use it back in my theatre prop construction days all the time, and I’ve seen it get used for making custom car panels as well. Same principle: spray a big gob of it on (since it sticks to everything, this is pretty easy), wait for it to dry, and then then carve it into what ever wacky shape you need. If it needs to be durable, you can coat it with fiberglass.
July 28th, 2008 at 6:24 pm
there has to be a way to get it off clothing–how…anyone, anyone?
July 29th, 2008 at 7:40 am
You may want to try a caulk remover. The brand I have (Lift Off, from Home Depot) claims that it works on expanding foam too. Note, however, it says nothing about working on clothing.
Your best bet is to contact the manufacturer and see if they have any suggestions (heck, Crayola has a 450 page PDF on how to remove their products from various surfaces).
Sorry; the clothing may not be salvagable.
November 17th, 2008 at 3:35 pm
Here’s what Dow tech support suggested about keeping a can reusable:
“One-component foams as GREAT STUFF(TM) do not lend themselves to re-use. Once a can has been used and allowed to sit for more than two hours, it will seal itself shut. This is indicated on the can’s label.
“It is possible to preserve a can of GREAT STUFF polyurethane foam sealant. Insert a pipe cleaner, soaked with WD-40, into the attached applicator straw (do not remove straw from can). Leave the pipe cleaner sticking out of the applicator straw approximately 1/4 inch. This has to be done within two hours of use. The WD-40 soaked pipe cleaner may preserve the can up to 30 days.”
November 19th, 2008 at 11:45 am
[...] we posted about Great Stuff Spray Foam, readers commented on the difficulty of cleanup and the “single-use” nature of the cans. One workaround [...]