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Mod Bit Flashing Details


caryseidner
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I'm sure this is not news to many of you, but it might be helpful for the rest.

These pictures show a necessary flashing detail for inside and outside corners, that I rarely see in residential work. We called them "footballs", but the hispanic roofers I worked with called them something else[:-censore.

When the mod bit sheet is cut so it can be folded up to form an inside or outside corner, there is a vulnerable area at the apex of the cut. These patches cover that area and complete the flashing detail. When these are missing, I know that the roof was not installed by a trained mod bit roofer.

Just thought I would share.

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tn_20101231511_P1000128.jpg

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tn_201012315157_P1000129.jpg

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Good stuff, Casey. Chevrons are also OK for inside and outside corners.

Download Attachment: icon_adobe.gif mod bit corner details.pdf

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Yea Mack, those work too. Doesn't really matter what shape the patch is, so long as they are present.

I think the guys liked the football shape because it was pretty easy to cut with a hook blade, and you could cut quite a few from scrap material.

In your detail it looks like they actually "set" the granules into the sheet before apply the patch. "Setting" the granules is done by applying a little bit of heat to the mod bit, and then troweling over the granules so they get buried into the bitumen. This way the patch can be applied to a smooth surface instead of a micro-mountain terrain. This is another indicator of a trained roofer.

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I don't think I've ever seen a cold application around here, and I look at hundreds of mod bit roofs every year.

Pretty much all torch down in Chicago.

You guys ever see cold patch (SBS)?

Once you have the big torch and know how to run it, I think torch is easier than cold patch.

I prefer APP over the SBS for a few reasons, the main one being you can "see" if the material is bonded by the squeeze.

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Just curious, but what would you expect to see in a location like that on a cold process installation?

Footballs?

Goop & granules?

- Jim Katen, Oregon

The details for cold applied are slightly different. You should still see the patch at the apex of the cut on the base flashing, but the rest of the detail would not be viewable. If it was done properly, a course of smooth surfaced mod bit would have been installed beneath the granulated sheet at inside & outside corners.

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Just curious, but what would you expect to see in a location like that on a cold process installation?

Footballs?

Goop & granules?

- Jim Katen, Oregon

The details for cold applied are slightly different. You should still see the patch at the apex of the cut on the base flashing, but the rest of the detail would not be viewable. If it was done properly, a course of smooth surfaced mod bit would have been installed beneath the granulated sheet at inside & outside corners.

Like this

Download Attachment: icon_adobe.gif MB_BUR_11_Inside_Corner_Flashing_Detail_-_PDF-9-1889-v2.pdf

52.16 KB

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I don't think I've ever seen a cold application around here, and I look at hundreds of mod bit roofs every year.

Pretty much all torch down in Chicago.

You guys ever see cold patch (SBS)?

Once you have the big torch and know how to run it, I think torch is easier than cold patch.

I prefer APP over the SBS for a few reasons, the main one being you can "see" if the material is bonded by the squeeze.

I don't see many cold applied systems around here. Primarily on schools, hospitals and other buildings that were specified by a roofing consultant contractor. The temp has to be above 45ish, and if it is that cold out you still would have to warm the adhesive so it will flow.

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Just curious, but what would you expect to see in a location like that on a cold process installation?

Footballs?

Goop & granules?

- Jim Katen, Oregon

The details for cold applied are slightly different. You should still see the patch at the apex of the cut on the base flashing, but the rest of the detail would not be viewable. If it was done properly, a course of smooth surfaced mod bit would have been installed beneath the granulated sheet at inside & outside corners.

Like this

Download Attachment: icon_adobe.gif MB_BUR_11_Inside_Corner_Flashing_Detail_-_PDF-9-1889-v2.pdf

52.16 KB

Thanks.

I don't see a lot of cold process installations, but it seems to be becoming more popular. The rumor I heard was that insurance companies were giving the roofers a break if they got away from the torch.

- Jim Katen, Oregon

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I don't think I've ever seen a cold application around here, and I look at hundreds of mod bit roofs every year.

Pretty much all torch down in Chicago.

You guys ever see cold patch (SBS)?

Once you have the big torch and know how to run it, I think torch is easier than cold patch.

I prefer APP over the SBS for a few reasons, the main one being you can "see" if the material is bonded by the squeeze.

SBS in general is a better product.

APP, which is only applied with a torch, gets brittle after it's exposed to the high temps of a roofers torch (1,400 F +/-)...at least that's what the scientists say. It sure is a hellovalot easier and cheaper to install, which is why we see it so much. That's also why we see it f'd up so often.

That being said it's still a very good product and works well when it is installed properly, which is very rare in residential.

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