When to use fireblock spray foam?


Old 12-15-14, 09:09 AM
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When to use fireblock spray foam?

When reading about air sealing, I see lots of mentions about using "fireblock" foam. Could someone clarify when or why this is needed vs standard foam?
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Old 12-15-14, 11:35 AM
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Mainly used when sealing up garages, around chimney's and Furnas rooms.
Old 12-15-14, 12:00 PM
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You can use the foam version to fill voids around pipes, ductwork and cabling from floor to floor to prevent the chimney effect. Standard foam is used to insulate, like around doors and windows, or in voids where air may infiltrate.
Old 12-15-14, 12:04 PM
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Code enforcement will vary, but anywhere the opening provides a vertical path that a fire could potentially follow. Horizontal holes through studs would be less likely to be an issue vs top and bottom plate. But all local code authorities have the final say. On chimneys and vent pipes the holes are often too large to be filled with foam or caulking. Then a fire resistant (approved) material like metal flashing can cover the opening and be sealed in place with the fire rated caulk or foam.

As for what your location in PA is requiring, only they know.

Old 12-15-14, 12:26 PM
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As mentioned, regular stuff is fine for doors, windows, rim joists, etc. For fire block, one of the primary areas is top and bottom plates, as in passing from one floor to the next, with basements or crawl spaces and attics treated as separate floors in this case. Basically you need to look at the potential of each stud bay as a chimney, and eliminate any intakes or outlets that could create a draft. If you wanted to caulk where a bottom plate sets on the subfloor to seal air intrusion, you use whatever product you want. Move to the center of that plate, where NM, a phone or data line, water line, waste stack, etc. passes through it, you use fire block caulk or foam. I have heard of some jurisdictions requiring it in horizontal runs through studs, every 10 feet, although I do not recall seeing enforced in my area, but it's not going to hurt anything to do it. We had a remodel last year where they had previously redone something with the subfloor, so that you could see a sliver of light from the basement along one of the first floor walls before the base was laid, and he was decent enough about it, but the inspector wanted that fire block caulked. So some of it is pretty universal, but you'd probably run into some things unique to your area.
Old 12-15-14, 02:22 PM
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One quirk over in NC is they require a fireblock of fire rated sheetrock at the 8' level in any chimney chase, and it must be sealed with the foam.

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