Mod Bit?

[Tim H]

This is the first roof of this type that I have encountered. The 'butterfly' roof over the main structure drains onto a flat roof that covers an addition. There are some problems that are obvious, but I found no signs of leaks in the attic. The flat roof has extensive alligatoring, but I do not think that it is a built-up asphalt roof,but maybe a rolled roof that has been patched with asphalt. I think that the 'butterfly' roof is a modified bitumen, but I am really unsure. It is stretched like a trampoline over the valleys (not bonded with the decking), and has signs of ponding, along with some questionable flashing. When the client (pre-listing), can find a reputable roofer with flat/low pitch expertise, they are going to have it evaluated and repaired (or replaced). Any comments as to materials or improper design/installation would be appreciated.

Thanks,

Tim

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[Jim Katen]

Originally posted by Tim H

This is the first roof of this type that I have encountered. The 'butterfly' roof over the main structure drains onto a flat roof that covers an addition. There are some problems that are obvious, but I found no signs of leaks in the attic. The flat roof has extensive alligatoring, but I do not think that it is a built-up asphalt roof,but maybe a rolled roof that has been patched with asphalt.

It's probably a built up roof with a cap sheet that's had additional asphalt applied over it.

I think that the 'butterfly' roof is a modified bitumen, but I am really unsure.

I think you're right. Despite it's ugly appearance, the material looks like it's in pretty good shape.

It is stretched like a trampoline over the valleys (not bonded with the decking),

That's wrong. (I can't see that in the pictures.) Still, if you avoid foot traffic over those areas, it might last as long as the rest of the roof.

and has signs of ponding, along with some questionable flashing.

The ponding probably won't hurt much, but those parapet flashings look pretty bad. If this were my roof, I'd pressure wash it, install new parapet flashings and put on a new white or silver coating. With that work I might easily get another 5-10 years out of it.

- Jim Katen, Oregon

[kurt]

Personally, I've never found poorly installed roofing to be trustworthy.

Crap installation of mod bit can show up in ways that one can't necessarily see from looking @ it; I'd be concerned that the laps were sealed adequately. It's amazing how laps can open up even when they look OK upon first review.

The alligatoring doesn't really mean anything other than the installer flooded too much tar; it isn't going to hurt anything.

I look @ approx. 300 flat roofs annually; I'd recite a lot of mfg's. installation spec's this roof doesn't have, and can it in my report.

And, there's no vents. Mod bit is amazing stuff; it keeps all the water out, and it keeps all the water in. It should have vents; I find all sorts of problems w/mod bit related to inadequate venting. Most roofers will insist it doesn't have to be vented. They're wrong.

Half assed "flat" roofing systems can have as many or more problems as pitched roofing systems; they can be very sneaky, because they can look functional, and then go to blazes in ways that one might not anticipate.