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17 votes
Accepted

Plumber set my bathtub on top of Great Stuff foam. Do I need to pull the tub?

Perfectly common modern technique. You should relax, and keep the plumber's number handy in the not-very-likely event that it "fails." Me, I use plaster, but I have nothing against foam done ...
Ecnerwal's user avatar
  • 218k
14 votes
Accepted

Would sprayed insulation under the roof deck cool down a hot attic?

Spraying the roof deck would create an insulated box. It's difficult to predict how that would affect average interior temperature. It would certainly increase roofing temperatures, which isn't ideal. ...
isherwood's user avatar
  • 139k
14 votes
Accepted

Looking for a non-stick space-filling foam

Fill a plastic bag with the polyurethane spray foam. The stuff expands a ton, so be careful not to burst the bag.
popham's user avatar
  • 10.4k
13 votes
Accepted

How can I remove cured expanding foam from floorboards?

I'd try scraping before sanding, using a razor blade scraper or a furniture scraper -- a slightly more targeted tool.
keshlam's user avatar
  • 29.5k
9 votes

Why would you ever choose open-cell spray foam?

Like most things, both have their benefits depending on the situation. Personally I'd default to using closed-cell unless there was a specific reason for open-cell, which can include: Open-cell ...
gregmac's user avatar
  • 29.1k
9 votes

Would sprayed insulation under the roof deck cool down a hot attic?

Note that there has to be airflow along most of the underside of the roof, to let the wood dry and discourage rot. There are channels you can buy to hold that space open; you would then install any ...
keshlam's user avatar
  • 29.5k
8 votes
Accepted

How can I store canned spray foam insulation for reuse weeks or months later?

You can reuse the same spray over and over simply by injecting some drop of acetone, then pour it out, and do it again 3 times to be sure nothing remains. The trick is to do it just after using it (...
JinSnow's user avatar
  • 526
6 votes
Accepted

Why don't conduit fill rules apply to cables encased in closed-cell foam?

The foam isn't the issue, but a lack of spacing can be Foaming NM cables into a wall (or otherwise burying them in thermal insulation) isn't considered to be an issue, provided that the cables were ...
ThreePhaseEel's user avatar
6 votes

Open cell spray foam offgassing 2 years later. How to fix?

This answer was posted by the asker as an update to the question instead of an actual answer. The problem fixed itself eventually. I followed the solution proposed by Wayfaring Stranger in the ...
4 votes

Why don't conduit fill rules apply to cables encased in closed-cell foam?

The limitations on cable in conduit have a whole lot more to do with the risk of physical damage to the cable. This is really hard to understand for Romex people, because they only know Romex and they'...
Harper - Reinstate Monica's user avatar
4 votes

Would sprayed insulation under the roof deck cool down a hot attic?

I would put a layer of batt insulation on the attic floor. An R-30 batt over the blown in stuff that you have. That would keep the heat from penetrating to the living area. Then check that your ...
RMDman's user avatar
  • 30.9k
4 votes
Accepted

How do I assess different insulation recommendations?

There are 3 issues embedded in your question, so I'll separate them. Issue 1 is the difference between a vented attic and a hot roof setup. A vented attic means that the roof stays cool, which helps ...
Cheery's user avatar
  • 5,940
3 votes

Engineer or Architect?

There are many kinds of engineers and most are specialists like: civil (water, sewer, drainage, etc.); structural; mechanical (plumbing? HVAC, etc.); electrical; acoustical; etc. Architects know ...
Lee Sam's user avatar
  • 23.3k
3 votes

Can I safely brush down old spray foam that is very dirty?

The dust by itself isn't dangerous since the foam's not breaking up but large quantities of regular dirt and dust are not good to breath under any circumstance. You would be better off getting a good ...
JACK's user avatar
  • 81.7k
3 votes

How can I store canned spray foam insulation for reuse weeks or months later?

While the glue's still fresh, wet a couple of cocktails sticks or matchsticks & insert them into the nozzle & both ends of the solid part of the trigger that screws to the can's nozzle. ...
Tetsujin's user avatar
  • 11.5k
3 votes

How can I store canned spray foam insulation for reuse weeks or months later?

You might consider upgrading to a pro foam gun: You would need to buy a refills, but they are usually cheaper and it will last for months because you can close the tip of the gun.
sdrawkcaB's user avatar
3 votes
Accepted

Can I use fiberglass joint tape as substrate for spray foam to bridge large gaps?

The best bet is to repair the ceiling so there is not a 2 inch gap. 2 inches is a substantial gap to have in-between drywall surfaces.
RMDman's user avatar
  • 30.9k
3 votes

Would sprayed insulation under the roof deck cool down a hot attic?

If you are going to spray foam, find a spray foam roofing company and have them spray foam the OUTside of the roof and finish with a white or silver coating. Other than that option, the other answers ...
Ecnerwal's user avatar
  • 218k
3 votes

Would sprayed insulation under the roof deck cool down a hot attic?

Your problem is solar gain vs the mass of your building. The sun is powerful. A dark, 1 square foot panel that is facing dead square on with the sun, will absorb 90 watts or about 300 BTU/hr from the ...
Harper - Reinstate Monica's user avatar
3 votes

How do I assess different insulation recommendations?

I just verified that Eversource is an actual utility. Much of my answer below was based on the idea that this company was purely a solar energy provider - i.e., a company that you contract with to ...
manassehkatz-Moving 2 Codidact's user avatar
2 votes
Accepted

How much closed cell expanding foam insulation do I need?

According to the product's data sheet a 750ml can yields 43l. I'm getting 0.86 square meters per can at 50mm thickness but I don't do stuff with the metric system often so I suggest you double-check ...
Sean's user avatar
  • 1,652
2 votes

How to insulate already-existing stud walls along block foundation

here is how we do block wall basement finishing - in almost 30 years i have never had a callback or any complaints about leaks after the fact. you do have to make sure the foundation is in good shape ...
personal privacy advocate's user avatar
2 votes

Considering replacing blown cellulose on attic floor with open cell spray foam. Should I just leave well enough alone?

Not crazy but quite unnecessary and counterproductive. Unless you are visiting your attic often there is no way for the cellulose to get into the living area of the house. Much less the cellulose in ...
ArchonOSX's user avatar
  • 20.1k
2 votes

What foam is best for sealing radiator pipes in floor to prevent mice from getting in?

No foam product will stop them, they will just chew through it. Some of them will eventually kill the mouse, but there's always another one, and another one, and another one to pick up the task and ...
JRaef's user avatar
  • 15k
2 votes

Old dryer vent in concrete

Nah. Build your new masonry exterior first, then if you need insulation spray foam from the inside. Foam breaks down over time with any sort of exposure.
Bryce's user avatar
  • 10.9k
2 votes

Should I use urethane spray foam or foam rope for caulking wide gaps?

There are pros and cons to each, making this a subjective question. Here are some comparison points. Rope caulk is easy to work with. You can take your time and not worry about anything curing too ...
isherwood's user avatar
  • 139k
2 votes

How would you plug this old weeping drain hole, in a brick/concrete retaining wall

Since it is leaking I would guess it is below grade, lucky it is only a couple of feet. First I would dig out the area at the crack now the tough part , clean the wall at the crack (a pressure washer ...
Ed Beal's user avatar
  • 103k
2 votes
Accepted

Spray foam insulation against metal roofing

Questions: Q1: Is this a reasonable/acceptable plan? Yes & no...more below. Meets code? You'll need to run all of this by your local/city inspectors/building code enforcement folks to get the ...
peinal's user avatar
  • 1,271
2 votes
Accepted

How should I apply spray foam around a ceiling mounted bathroom exhaust vent?

Rather than using that spray foam you'd be better off getting a sheet of Styrofoam and cutting it to fit the opening around your fan. Make a template out of cardboard and then trace it on to the ...
JACK's user avatar
  • 81.7k

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