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smarcus

Fully Adhered

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I think I've been through most of the posts in this forum and I don't recall anything about modified bitumen sheets and being fully adhered. The seams were all heat welded and mostly sealed well, the exception being the pictured seam. I was pretty surprised when I looked at the seam and pulled up on it a little to see how loose is was when the entire sheet lifted up a little, but stayed together. all the seams and parapets are sealed, the sheets are all loose. I tried in a couple other areas where i could and all the same. There are some wrinkles or blisters. Some of the installation instructions I have seen don't specify that the sheets be fully adhered, just the flashing sheets. I don't believe it to be ok, specifically because the risk of tenting or blow off. Is there a reference for fully adhered cap sheets.

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It looks like your basic quick and dirty 2 flat roof to me.

No bleed @ the seams, the chimney lacks a mechanical fastening system/termination bar, it's wrapped up the parapet (not normally a problem @ the common brick sidewalls, but definitely a problem @ the front cornice), no cants @ the transitions, etc., etc., etc. Not all mod bit has to be fully adhered, although most are.

I'll grudgingly concede it will probably still work OK because the problems don't usually come from what you're concerned about.

The rear gutter detail is critical, as are any of the penetrations. Don't wrap it up over the parapets. Check the side parapets for the usual crap repairs with the wrong mortar.

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What's a bleed at the seams Kurt?

What is what do Oprah Winfrey's dresses do?

We're not playing jeopardy? Oh.

It's the schmoo that bleeds out between the layers when they're heated and compressed.

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They always do the rear gutter detail wrong, just wrap the last cap sheet down into the gutter and fasten the gutter hangers through the sheet. Its mostly what I see with mod bit roofing.

And thanks for the reply Kurt, that would be why I couldn't find any information on fully adhering cap sheets.

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What's a bleed at the seams Kurt?

What is what do Oprah Winfrey's dresses do?

We're not playing jeopardy? Oh.

Too funny Chad.

Reminds me of when I was watching Johnny Carson, doing the Carnac bit, and he holds the envelope up to his head and says Yasser Arafat - he opens the envelope and says What is the sound Dolly Partons bra makes when she takes it off?

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Besides no term bar at the parapet, the parapet wall is missing a base flashing. That will need to be re-done.

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tn_2011615205534_base%20flashing%20pic_Vga.jpg

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tn_201161520561_base%20flashing_Vga.jpg

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Is there a reference for fully adhered cap sheets.

I believe there is. Google GAF and John Manville mod bit specs.

From JM for asphalt embedding: The modified bitumen sheet can

be rolled, scrolled or flopped into the asphalt. Regardless of the

application technique employed, the crucial factor is that the modified

bitumen sheet make complete contact and embed in the hot asphalt.

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Is there a reference for fully adhered cap sheets.

I believe there is. Google GAF and John Manville mod bit specs.

From JM for asphalt embedding: The modified bitumen sheet can

be rolled, scrolled or flopped into the asphalt. Regardless of the

application technique employed, the crucial factor is that the modified

bitumen sheet make complete contact and embed in the hot asphalt.

Flopped?

I'm not familiar with that process.

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Besides no term bar at the parapet, the parapet wall is missing a base flashing. That will need to be re-done.

Click to Enlarge
tn_2011615205534_base%20flashing%20pic_Vga.jpg

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Click to Enlarge
tn_201161520561_base%20flashing_Vga.jpg

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I know you're right, but you also know that there's only a few hundred thousand 2-3 flats that don't have base flashing, and they work just fine.

I don't usually call base flashing unless there's so much other stuff, I feel like piling on.

I'm happy if I can just get the gutter and penetrations details right. Parapets is like frosting on the cake.

If I can get folks to do this, I'm reasonably happy.......

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I think if the roofers are drunk and fall into the asphalt it's called a flop.

This is from JM F. End laps shall not occur in a continuous line and should be broken by a minimum of 3 feet. Uniformity

of the separation of side laps is desirable for best appearance. All sheets must be firmly embedded in

the hot asphalt and be free of wrinkles, buckles, blisters, fishmouths, or voids. End laps must be nailed

on all slopes exceeding 1 inch per foot.

There are three acceptable methods of application:

1. The “flop inâ€

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I choose my battles........

Base flashing ain't one of them.

I suppose if I know it's going to court, I'd call it out, because you're right, it's wrong.

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