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I've received quotes from two different roofers for the installation of an elastomer membrane on a low-slope roof.

The first roofer is installing a fire-proof netting, followed by a membrane that is nailed down, followed by a membrane that is welded on.

The second roofer is installing a self-adhesive membrane without a fire-proofing layer. He claims that because no nails are used the membrane acts as a fire-suppressant by itself.

Is the second roofer correct? Do self-adhesive membrane installations require a fire-proof layer?

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"Fireproof netting"??? I've never heard of such a thing. If it's netting, then there are "holes" in it AND THEN ITS NOT FIREPROOF. The netting might be fire retardant, but it's not a fireproof membrane. We worry about the exposed surface to make the roofing "fire retardant".

It might be an "isolation fabric". They are used between the roofing and the old roofing. (You want the new roof to move independent of the structure.)

The second roofer's "peel and stick" type roofing has problems too: 1) most are not UV protected (I'd be skeptical and demand to see the "Product Data Sheets".) They are made to be installed under another type of roofing, (I.e.: composition shingles, metal roofing, etc.) 2) When installed over an entire roof, it doesn't allow the roof to breathe. Usually, this type of roofing is used in valleys, at eaves for ice dams, around difficult areas like vents, etc. in low slope areas, etc. and then covered with another type roofing. 3) When fully adhered, it will move with the roof structure, which can put stress on the membrane and it could tear (fail) over time. The second roofers statement about its fire suppressant because it doesn't use nails is wacky.

In low-slope applications, I like thermoplastic (TPO) or PVC roofing...never use EPDM roofing...it can come apart over time. The first roof sounds like one of these (TPO or PVC) with a "mechanically fastened" installation, (nailed down).

If fireproofing is important, I'd use metal roofing with a low-slope application, otherwise I'd use TPO or PVC roofing with mechanical fasteners and "heat-welded" to the fasteners for low-slope applications.

(Btw, if you live in a high wind area, make sure you get the proper number of fasteners per square foot. Check with the manufacturer.)

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  • For the first guy with the "fireproof netting", the exact wording from the quote is lnstall 1 ply 15 lbs felt paper as a fire retardant and Install 1/2" securepan fire retardant fiberboard insulation. Does that make more sense? How good is that? He is using "Soprema Soprastar white" for the finishing/top membrane but did not mention what the base membrane is made out of. Is this okay? Should I inquire about the base membrane? For the second guy (self-adhesive membrane) they are using COLVENT 830. Is this UV protected? – Gili Jul 31 '17 at 15:16
  • I googled colvent 830 and it's the base. It is covered with the Soprema finish membrane. The base goes down on a "primed" surface (a goo like material painted on the surface) or a 1/2" layer of insulation. I like the insulation because it will isolate the roofing from the building. With insulation, I like this system better. Do you need extra fire protection on the roof? Do you live in a high wind area? – Lee Sam Jul 31 '17 at 15:57
  • I live in Montreal (Canada). I want the same fire protection as all other residential homes have. I don't think we live in a high wind area per se. We get high-speed gusts 1-2 times a year as winter approaches. In light of that, how do the two roofing options compare? – Gili Jul 31 '17 at 19:13

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