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Modified Bitumen Applications


CNewhouse
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My inspection today had a modified bitumen roof. I don't see product this often, aside from the occasional neglected detached garage. Reading through a few installation manuals made me realize how many different application options there are. The roofing today had no bitumen squeeze out at the overlapping seams, which had me thinking that the bitumen wasn't properly heated before being applied. Could it be that this is a self adhesive membrane, hence the lack of squeeze out? The end laps were very poorly adhered and lacked proper offset and the flashing details were a bit screwy so I recommended a roofer take a peek either way, but I'm curious how one knows which application method the "roofer" was attempting to apply.

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IMG_8773.HEIC IMG_8775.HEIC

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That's definitely a self-adhering product. While I'm not very familiar with the proper installation of this product - I usually see the torch-down version - I know enough about it to recognize that it's usually installed wrong. The end laps are supposed to be offset at least 3' and you're never supposed to bond the adhesive to the granules - at those locations, you're supposed to use mastic. The adhesive only goes onto the portion of the product that's meant to receive it. 

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That's what I was leaning toward after doing some reading. Is there a visible difference between the roofing used in the different applications once installed? Aside from the presence of squeeze out from a torch down application or excess asphalt from hot mopping? 

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2 hours ago, CNewhouse said:

That's what I was leaning toward after doing some reading. Is there a visible difference between the roofing used in the different applications once installed? Aside from the presence of squeeze out from a torch down application or excess asphalt from hot mopping? 

My understanding is that squeeze-out is something you'd expect see on a molten asphalt mopped-down installation.

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4 hours ago, Marc said:

My understanding is that squeeze-out is something you'd expect see on a molten asphalt mopped-down installation.

Several of the installation PDFs I've read through say that bleed out should occur at all laps when using the torch-down method to ensure a proper seal. This screenshot is from the Soprema SBS Roofing Guide (within the heat welded application guidelines).

Bleed Out.png

Edited by CNewhouse
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