"GREAT STUFF"

[MiamiCuse]

I have a question on those foam sealant especially the GREAT STUFF products.

First, I think those are basically for insulation and nothing else, right?

Would you use it in places where no insulation is necessary, but you still want to put up a water tight barrier?

For example, I have a 3" PVC pipe that exits the house below the slab through the block wall (the block wall extends below the slab to at least 24" below, don't really know how deep it goes have not got to the bottom of it). Anyways I drilled a hole through the block wall about 3"x3" for the pipe to pass. The hole is uneven and it's through a hollow block wall. I don't need to insulate it since it's 18" below my concrete slab, but I want to stop bugs, tree roots, rodents, or rain runoffs from coming through it. I patched it with concrete mix on the outside of the hole. But the entire hollowed space in between, do I spray the cavity with this foam stuff?

Are there any fundamental differences between the Fireblock foam, door and window foam, cracks and gaps foam and big gap foam?

There are many places in my block wall electricians have hollowed out for recessed boxes. I am thinking of filling those with foam. However since the wall is made of hollowed concrete blocks, the space behind the hole is big, sometimes it extends above and below to the voids of the adjacent blocks. Being in Miami I would like to insulate best I can. What do you recommend be the most effective way to seal these holes?

These small cans are expensive at $4-$7 a can. If I need larger quantities, they don't sell them in garbage can sizes?

MC

[RicodJour]

Bugs, particularly ants and termites, love eating the foam for some reason. You don't have ants or termites in your area, do you? Yes? Below grade is a bad idea. DAGS.

R

[DD_BobK]

MC-

I would have shoved some hardware cloth into the cavity and filled with cementious material. Maybe sleeved the block by dry packing the next 1/2 sized pipe in place and then caulked the resulting annual gap.

Those canned foams are ok for some uses but they aren't cheap, hard (impossible?) to re-use and not very strong. One trick to discourage rodents is to embed 1/4" hardware cloth in the foam. The little critters give up & look elsewhere.

Bugs don't "eat it" per se but they do eat "chew" into it, burrow, nest, etc. Its a decent weather barrier (if covered) but cannot survive the sustained attack from animals. I tend to consider more like very soft wood & only use it were wood is appropriate (a bit conservative)

I have drain plumbing penetrations through the sills of my 1930's house that have been filled with a simple cement / sand mix ...still working just fine. If there are small gaps, I fill with latex or epoxy caulk to limit air infiltration and insect access.

Hilti makes a more professional gun type foam applicator that uses sightly bigger cans and is somewhat cheaper per in^3.

cheers Bob

[Van Chocstraw]

I also use it to fill in chipmunk holes on my lawn. I take a piece of plywood, make a hole in it just big enough for the great stuff straw, cover the hole and empty the can. It must go quite deep and fill all the areas.

[gfretwell]

"Discourage" is the right word. A motivated rat will chew right through hardware cloth. Usually rats chew to get out and then come back in that way once they establish the route.

[DerbyDad03]

re: Are there any fundamental differences between the Fireblock foam, door and window foam, cracks and gaps foam and big gap foam?

There are differences in the expanding properties of the different brands/types. There are "expanding foams" and "minimal expanding foams". Polyurethane foams and Latex foams. There is also Foam Pressure to consider. Low Pressure does not necessarily mean Low Expansion.

For example, take a look at the Great Stuff Window and Door compared to DAP Window and Door.

Great Stuff says to fill the cavity to 50% to allow for expansion, DAP says to fill to 90%. (I just did a window with DAP and I can attest to the 90% number.)

I've heard of issues with some foams actually bowing the frames of vinyl windows due to over-expansion. DAP is supposed to be safe in that regard. There are other brands such as Hilti to consider also.

Check out this thread:

[Red Green]

[e-mail] wrote in news: [e-mail]:

Enough with the political comments :-)

[The Daring Dufas]

That stuff works great up the tailpipe of some jerks BMW too.

TDD

[Van Chocstraw]

Depends on how soon after they start the car. They could just blow it all out if it's still wet.

[The Daring Dufas]

That's why you use a long extension tube that will reach way up in there to the muffler. *snicker*

TDD

[aemeijers]

A large Idaho potato and short length of broom stick works well, and is a lot cheaper.

-- aem sends...

[The Daring Dufas]

The tater is easy to get out but a muffler full of foam.........

TDD

[Stormin Mormon]

I have used the foam to fill in voids, in vehicle sheet metal. Helps keep moisture out, and rocker panels and such last a lot longer.

I've heard that criters and insects don't go near it, but others have found differently. I'd go ahead, and foam it in. A couple of hints from experience:

• You get one use of the can. Plan several projects, and use the entire cat at one time.

• The uncured stuff doesn't come off of hands, clothing, etc. Handle it like chem bio waste, and don't touch it.

• Have an empty shopping bag, in your pocket. When you're finished, shove the can and tube into the bag.

• After it's cured (next day) you can trim or shape it with razor knife, or sharp steak knife. Cured foam is not dangerous to hands, clothes, etc.

[aemeijers]

(snip)

Maybe in warm and/or dry areas. I tried that up here in salt country once, and it rotted the whole area out, while the rocker/C-pillar on the other side stayed fine by comparision. I ended up popping the bondo plugs out, and digging the foam out as best I could with a coat hanger, and mudding the whole thing with the fiber-reinforced bondo stuff over the traditional filler of wadded up window screen. Best I can figure, since the space wasn't totally filled or sealed, it held water against the backside of the bare steel in the dead space. It seemed like a good idea at the time, but it bit me in the butt. Perhaps if it was done on bone-dry virgin metal where rust didn't already have a foothold, it would work better.

-- aem sends...

[RicodJour]

I wouldn't count on it. It's the same thing as a building. It either dries to the inside, or dries to the outside. If you prevent drying, you will get rust.

R

[Stormin Mormon]

Rochester, NY is neither warm, nor dry. And they salt the roads to excess.