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Roll Roofing or Modified bitumen


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This was my first flat residential roof. Iv'e seen roll roofing on low slope applications and that is what this looked like to me,however, I have been reading and now I wonder if this is a modified bitumen. The roof had a crown that sloped to each side and the seams ran in the direction of the slope. Past leaks in the home but all appeared to be currently dry.

Any thoughts on this. My client is aware of my limited knowledge on a flat roof and I told him I would do some research on the subject.

I really thought I had taken more pictures.


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It looks like mod bit. If you press your thumbnail into the edge of rolled, and then mod bit, you'll never have to ask again.

Consider a publication about low slope roofing from the National Roofing Contractors Assoc. Many manufacturers (and expert witnesses) refer to NRCA specs.

Local chapters of HI orgs should have covered mod bit by the mid-80s. I find many HIs (and installers) not familiar with this stuff. Might be time for the continuing ed. committees to revisit low slope roofs.

ps. Bad, bad & bad parapet.

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Granulated Mod Bit; can't get rolled to do what they're getting this stuff to do.

Lots wrong....

1) No termination bar/mechanical fastener @ the parapet; the stuff will peel & further destroy the (already crappy) parapet.

2) No kants in the corners & roof/wall junctions.

3) Flashing is all screwed up.

4) I'd bet a tooth the eave edge detail is wrong; they always are.

I'm sure there's more, but that's a decent start.

Go here.

http://www.gaf.com/General/ProductsNew. ... %20Details

Look @ all the flashing details for mod bit. Once you see how it's supposed to be done, it's real common sense stuff. Of course, don't expect to ever see it done right. I've looked @ approx. 6000 mod bit roofing systems, & I've never seen one, not even one, that had every detail right. A couple were pretty close, though...

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Man you guys kill me! I worried that the pictures I had wouldn't give you enough to make any judgement or observations.

I am going to go back this weekend (vacant) and really look this thing over. Client was pretty certain he was gonna need some roof work.

Another reason why this place is the best.

Thanks Ya'll,


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For those that want to really know how low pitched roofing systems are supposed to be specified and installed there is a program offered in Denver. I went to it about 10 years ago and it was very useful. Additionally, I got to see Denver!


Check out the online training info as well. The introduction to commercial roofing systems provides a good basic lesson on the different systems with photos.


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