I was talking to a friend today who has 30 yrs in heating and insulation and he was warning me strongly against spray foam for my house because, among other things, it was “too rigid”. He said that over time it won’t expand and contract as the rest of the house does causing it to lose its sealing properties.
I have read a lot about the foam, here and elsewhere, and was convinced it was what I wanted for my house, but this is the first I have ever heard of this concern. Has anyone else ever heard this before? Is it a valid concern? Is there any test data on this kind of thing?
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That's the way I've always done it...............and I'm gonna die doing it that way.
Where have I heard this before? What magic system does he use that retains it's "sealing properties"?
Your buddy is 20 years behind.
Joe H
sounds like it borders on BS to me
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I have worked with spray foam that is several years old and I find that it is still slightly flexible. Not obviously so but the amount framing moves, assuming sound construction and only temperature and moisture changes causing movement, is a rather small amount. IMHO, but without real scientific evidence, the foam should be able to handle this small amount of movement.
I have found that if the foam is exposed to sunlight or ozone, as when close to some electric motors or any arcing, it degrades, darkens and becomes both less elastic and more friable. Even in this case I have seen the bulk of the foam, underneath the exposed skin seems to last fairly long. A foamed hole in a wall exposed to direct sunlight, this is Florida so be assured the sun was not kind, has remained largely intact, with some surface wear, after eight years with no protection.
not to be insensitive ..what about comparisons of the foam on the Space Shuttle? IIRC it was basically the same stuff, on the external tanks, not the actual shuttle.
If that foam was "flexible" would it have damaged a ceramic heat shields adhesive? And the foams that I can buy to spray sure is a helluva adhesive.
curious on your take.
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Difference is the speed of the interaction. Water is pretty soft until you do a belly flop. Hit it at aircraft speeds and it is like hitting a brick wall. The same is true, IMHO, of the foam that hit and damages the shuttle. The shuttle was doing several hundred miles an hour.
The movements of the framing of a house, assuming it is not being hit by a tornado, is a small fraction of an inch in a couple of days. Most of this foam you can press on with a thumb, without going too far and damaging it, and feel it give slightly. I would think it would give enough to take up any slack, particularly if it is firmly bonded to the interior surfaces.
Next time er in Mickie Ds, get a foam cup of coffee and squeeze it. See how rigid it is. Make sure the coffee is real hot.
Not.
SamT
There are a variety of spray-in-place insulating foams. Icynene stresses that it is flexible in advertising. Polyurethanes come in varying degrees of flexibility/rigidity.
A web search of "Icynene" or "spray urethane insulation" will give many articles discribing the qualities of the foams.
Not directly on topic, but a related article from the Journal of Light construction:
http://www.ncfi.com/Insulation/JLC_SPF_Artcle.pdf
>Polyurethanes come in varying degrees of flexibility/rigidity.
The PUF comes in <2# densities to 3# or greater. Each has the same insulation rating / inch. Difference is size of and number of cells, and that translates into rigidity, too. For a residence, can't imagine 2# wouldn't expand/contract with the building.
They've been using SIPs for well over 50 years now (Original use was refrigerator panels) Check the heating bills of any house built with SIPs and compare it to the house next door.
There are 25 year old SIP paneled houses out there and 50 year old walk in freezers..
Lot of places for you to confirm the viability if foam as an insulating material..
We used the corbond 2# density foam in our home. It sticks to eveything an i don't see any signs of it separating from the framing, it has enough flexibility in it to follow the movement in the framing. I would not hesitate to use it, it's hard to get people to spend the money for this system.