Author Topic: Foam in existing wall cavity with fiberglass insulation  (Read 2499 times)

Bud9051

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Re: Foam in existing wall cavity with fiberglass insulation
« Reply #10 on: January 16, 2011, 03:34:33 PM »
I had an application a few years ago where I needed to install 2" foam 4' out around a commercial slab, but the occupant was going to be an auto service garage and in front of the doors would unavoidably be subject to lots of petroleum products.  Standard pink and blue, melt.  I ended up covering those spaces with a rubber membrane which seemed to make everyone happy, but a foam insulation product that is unaffected by chemicals is interesting.  And the tripolymer is apparently totally stable when buried and it gives off no poisonous gasses if I'm reading it right.  I have a couple of sheets of 2" blue that were in storage and attacked by little tiny ants.  They loved it, I didn't.

Update, I did some reading and the information was clear as mud.  I couldn't separate the chatter about formaldehyde and this product.  It seems clear to me, but it certainly wasn't in the discussions I read.  That confusion would currently leave me on the sideline waiting for a better consensus.

Bud
« Last Edit: January 16, 2011, 04:52:06 PM by Bud9051 »
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Huisjen

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Re: Foam in existing wall cavity with fiberglass insulation
« Reply #11 on: February 08, 2011, 07:43:46 AM »
Maybe I've missed it in discussion so far, but there are injection and pour-in foams that are very different from spray foams.  They tend to be fragile, brittle, less resilient than spray foams.  There are several different products within this class, with more coming to market.  Some have a significant amount of water, which is supposed to vaporize due to the heat of reaction when the foam is installed, but if not vented somehow, it will re-condense somewhere within the structure.

As for installing them where FG is already in place, they are marketed with that effect in mind.  The installer is able to insert the tube and the foam pushes the fiberglass out of the way as he pushes the tube in.  It fills the wall cavity as he withdraws it, packing the glass down fairly tight.  This is an advantage over blown dense-pack cellulose, which won't compress FG and will hang up on obstructions.

Dan

David Meiland

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Re: Foam in existing wall cavity with fiberglass insulation
« Reply #12 on: February 08, 2011, 08:57:45 AM »
there are injection and pour-in foams that are very different from spray foams

My understanding is that the pour-in foams are similar to spray foam in that they expand quite a bit to fill the available space, whereas the injection foams (such as Tripolymer) are pre-mixed and almost fully expanded when they are installed. The injection process puts the foam under pressure into the cavity, theoretically filling the voids and even moving the FG out of the way. There is supposed to be minimal further expansion in order to avoid bulging or blowing off the drywall.
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Robert Siessel

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Re: Foam in existing wall cavity with fiberglass insulation
« Reply #13 on: February 25, 2011, 04:58:19 PM »
We have had good results with Tripolymer here in central New Jersey. I would prefer to fill cavities with little or no insulation in them, but we also inject when existing batt insulation is present. The foam does not expand like spray foam and has the consistency of a heavy shaving cream. It will seek and fill voids and cracks that batts or dense packing might not get to. It sets up quickly and ends up a little softer then say ridgid poly. In addition to added R value, (close to 5 per inch) it's an excellent air sealer. The delivery system is finniky and equipment needs alot of attention. I feel it's a great retro fit product and the only product I know of that can be injected through brick and stone. Hope this answers some of the questions in this thread.

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