Spray Foam Question

NCDeere

Howdy. I have been lurking on this site for quite a while and really like it.

I have a question regarding spray foam insulation. I know that it can be 2-3 times more costly and that over time you will recoup your money through energy savings, but when I see it going in on TV, I keep having one question. If you ever need to modify your wiring or plumbing in a foam wall, it seems to me that you are out of luck and will have to destroy the insulation to get to it. I mean heaven forbid that you would have to do something like that but you never know.

So, how would I address repairs in a spray foam wall. Or am I worried about nothing?

Any other info you have that could push me in one direction or the other on using spray foam would be appreciated.

Thanks for your help.

Bryan
Iron Station, NC

Chris Johnson

If you needed to modify something, do so and replace the foam, small jobs have spray cans available, medium have Pak Kits available and larger ones, bring the spray foam guy back in

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Chris

genecarp

you could also modify the affected area with fibreglass insulation.

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JohnS

The worry about having to modify is a legit one but as was said earlier, the use of small kits and cans can make filling in and repair work very quick and easy. When changes have to be made the kits and cans can be done by most anyone as long as proper safety ventillation is obtained during the work.

parts

What happens if you need to replace the roofing sheathing were it has been sprayed? Also repair after a fire? The only way I can see getting out is with an adze

rc-construction

A $150 froth pak.

WNYcarpenter

it takes less space to get the required R value in spray foam than fiberglass. The stud bays aren't filled to the full width if the wall framing is 2x6, or 2x12 for the roof.

Wires are generally still accessible after insulation....ask the GC how many inches are being sprayed then you'll know the depth to run your wires.

We've started using foam a lot more recently...we do it in 2 shots.

1" after the house is weathered in to seal it up and to start drying out the lumber then finish after the rough ins before DW.

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dlarrivee

What on earth are you talking about "depth to run your wires" it's not like you can run wires right near the interior face of a stud and pass any electrical inspection anywhere...

katoman

Contrary to what the foam and shingle manufactures will claim, DO NOT foam against your roof sheathing unless you want to replace your shingles in a year.

Install baffles all the way from soffit to ridge if it's a cathedral ceiling. I worked for a new home builder who made this mistake on the first few with cathedral ceilings and the shingles failed in a year.

After we began installing baffles we had no further problems.

SLSTech

Well I am sorry to hear you had problems but I doubt it was the foam - I can & I am sure many other members here can snap pictures of houses that have not had any issues like your describing.

The main problem with many of these installations is they do not understand how to tie everything together &/or they use the wrong materials.

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zab

conduit

tcleve4911

Nobody's gonna run conduit.....geez

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zab

i should have specified flexible conduit. its a bit overkill for resi applications, but in my opinion completely worth it.

tcleve4911

Cost?

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smeagol

We tore off a church that had osb on top of rigid foam(5 Years OLD) Most spray foam companies we've dealt with net and dense pack the parralel chord vaults and still run chutes full length. Thats with trusses though and with stick frame i'd guess you need foam for the r-value.

Tom Struble

when you run chutes full length in a rafter bay,how does that remove any heat and moisture from that bay?Or do we just assume that with dense pack or foam there won't be any moisture migration?Cooler directly under the sheathing is better for shingles I'm sure but don't most shingle man. say its OK to use them on a ''hot''roof?

this is just a question that's been in my head,seems the more i read building science stuff the less I'm sure of about anything

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Tom

tcleve4911

I agree, Tom.

Every time I get my new issue from Finehomebuilding, or JLC, or This Old Shack and then going on line, I continually get mixed messages about ventilation, insulation, wraps and plastics and radon and CO and geez it goes on & on.

We should just live like our ancestors did in a drafty, stick house with no insulation & dirt floors.

But then we wouldn't have a great forum like this would we?

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