# open cell sprayed insulation and PEX



## MLMIB (Aug 12, 2010)

I can't imagine that any curing chemical reaction would be hot enough to cause a problem with water pipes. the PEX has an upper limit of 200 degrees F according to...
http://www.ppfahome.org/pex/faqpex.html

I just had spray foam put in a while back, probably open cell, and it was water based with no hot chemical reaction. What is your concern based on? source?


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## danster44 (Sep 25, 2011)

MLMIB said:


> I can't imagine that any curing chemical reaction would be hot enough to cause a problem with water pipes. the PEX has an upper limit of 200 degrees F according to...
> http://www.ppfahome.org/pex/faqpex.html
> 
> I just had spray foam put in a while back, probably open cell, and it was water based with no hot chemical reaction. What is your concern based on? source?


just hearsay on the internet -- one example:
http://www.heatinghelp.com/forum-thread/131323/Pex-Tubing-and-Spray-Foam-Insulation


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## MLMIB (Aug 12, 2010)

it also depends on what the foam is that you're using. I used applegate foam and the chemical reaction was really just drying I'm pretty sure, but I don't know what the chemical reaction is that your stuff goes through. If you list it I'm sure someone can look into it.


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## Msradell (Sep 1, 2011)

I recently sprayed all of the PEX tubing for our bathroom remodeling project with closed cell foam without any problems. We sprayed 6" in three layers and everything went smoothly.

Is there a reason you're using open cell instead of closed? Closed has a higher R-value and provides a vapor barrier and air seal.


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## AGWhitehouse (Jul 1, 2011)

Msradell said:


> We sprayed 6" in three layers and everything went smoothly.


That's the key!!

Open cell foam is really forgiving when it comes to curing requirements and heats, but closed cell is not. You are only supposed to spray closed cell in 2" lifts to ensure that the heat generated during the component reaction can escape the foam. Spraying too thick traps the heat and creates high temperatures that can damage the closed cell structures and overall integrity. There have been cases where closed cell foam has actually burst into flame from too much heat being trapped. This heat is likely enough to damage PEX tubing since it is also plastic in nature.

Article for the noted fire case: http://www.buildinggreen.com/live/i...usetts-Fires-Tied-to-Spray-Foam-Incite-Debate


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## danster44 (Sep 25, 2011)

Msradell said:


> I recently sprayed all of the PEX tubing for our bathroom remodeling project with closed cell foam without any problems. We sprayed 6" in three layers and everything went smoothly.
> 
> Is there a reason you're using open cell instead of closed? Closed has a higher R-value and provides a vapor barrier and air seal.


I questioned the installer I'm going to use -- he tells me his foam is open cell --
I've read that closed cell is better, but I'm going with what this guy offers --
he's doing 5200 s.f. (surface) for $3000 -- my other quote was $6000

(2) 24 x 30 x avg 15' high and the underside of (1) 24 x 30 (non A/C "dog run")


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## federer (Aug 20, 2010)

isnt the issue with closed cell that if a leak develops you cant tell since its blocking the water from coming through?


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## danster44 (Sep 25, 2011)

federer said:


> isnt the issue with closed cell that if a leak develops you cant tell since its blocking the water from coming through?


I believe that is correct -- CLOSED CELL is a vapor barrier - OPEN CELL is not --

Closed cell is rigid / dense (can augment the structural integrity of the building)
but cost 2-3x what Open cell does.


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## Msradell (Sep 1, 2011)

danster44 said:


> I believe that is correct -- CLOSED CELL is a vapor barrier - OPEN CELL is not --
> 
> Closed cell is rigid / dense (can augment the structural integrity of the building)but cost 2-3x what Open cell does.


Providing a vapor barrier is a good thing, not a bad thing in most cases. In most areas the cost difference is significantly less than what you are mentioning, usually only about 25% higher.


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## danster44 (Sep 25, 2011)

Msradell said:


> Providing a vapor barrier is a good thing, not a bad thing in most cases. In most areas the cost difference is significantly less than what you are mentioning, usually only about 25% higher.



I wish that were true (25% cost differential) in our neck of the woods -- I think I would opt for the CLOSED cell spray -- I'm told by the bidders I've talked to that because of "yield" and other factors, closed cell is at least 2X the cost of OPEN.


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## AGWhitehouse (Jul 1, 2011)

federer said:


> isnt the issue with closed cell that if a leak develops you cant tell since its blocking the water from coming through?


Water under pressure will not be contained by the foam...It will find a way out, though it may not come out directly next to where the leak is.


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## federer (Aug 20, 2010)

AGWhitehouse said:


> Water under pressure will not be contained by the foam...It will find a way out, though it may not come out directly next to where the leak is.


so eventually the water will still leak through closed cell foam. how long does that take?


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## Windows on Wash (Aug 30, 2011)

federer said:


> so eventually the water will still leak through closed cell foam. how long does that take?


Closed cell foam will essentially keep the water contained to the opposite side the the foam for just about ever. Where it will come out is where there is a breach or seam in the foam.

Open cell foam will allow the water to flow through, not exactly where it comes in, but somewhat through over time. 

Amount of time depends on volute of water and depth of foam. There are no real established guidelines.


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## AGWhitehouse (Jul 1, 2011)

federer said:


> how long does that take?


There is no way of predicting this. But a leak within closed cell foam will eventually come out. How quickly and how much will actually leak is unknown. The only way I can see that it would contain a leak is if the foam was structurally supported on all side of the leak spot so that it couldn't flex or crack under the new pressure loads.


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## forresth (Feb 19, 2010)

I bet it would not be a problem with water in the pipes, even if it would be a problem with dry pipes.

I bet you could do a light spray over the PEX, let is set and cool while working elsewhere, then do the full spray. The initial spray would protect the pipes from the heat of the full spray.


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## bubbler (Oct 18, 2010)

MLMIB said:


> I can't imagine that any curing chemical reaction would be hot enough to cause a problem with water pipes.


Massachusetts Fire Officials Urge Caution With Spray Foam

"_It's well-known that two-component spray polyurethane foam (SPF) gives off a substantial amount of heat as it cures._"
...
"_...at least three fires, one being a fatal fire, are believed to have been started during the application of spray foam insulation, and currently remain under investigation._"


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## Windows on Wash (Aug 30, 2011)

+1 

Spray foam contractors know that insulation needs to be done in layers to prevent excessive heat build up. Get a contractor that knows his trade and you will be fine.


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