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Modified bitumen roof seam issues (C) Daniel FriedmanModified Bitumen Roof Life FAQs
Q&A on defects & life of modified bitumen roofs

Q&A on modified bitumen roof defects, wear signs, life expectancy, life extension by coating.

This article series describes common defects found on modified bitumen roofs such as buckling, cracking, granule loss, improper installation details, leaks.

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Modified Bitumen Roofing Life FAQs

Modified bitumen roof life question - browning on hot days (C) Inspectapedia.com John LThese questions & answers about the typical life expectancy of Modified Bitumen Roofs and related mod-bit roof defects were posted originally at MODIFIED BITUMEN ROOF DEFECTS & ROOF LIFE - be sure to review that original article as well.

On 2018-07-08 by (mod) - mysterious brown seams on modified bitumen roof

Interesting. My research so far has not found reference to this problem .

I'll look further.

It's possible that there is a bit more dust, dirt, even algae or mold accumulating at roof seams simply because the texture and chemistry of those heated, lapped joints is a bit different than in the field of the roof.

On 2018-07-08 by John L.

On another note, my next door neighbor just completed a cold application a couple of weeks ago. His also has the same discoloration. Either it’s the way the sun shines on the roof or the change Or Temperature changes the mineral

On 2018-07-08 by John L.

It was a hot or torchdown application. We’re they experienced? Hard to say. I’m not entirely happy with the crew

. I can tell you everything is tacked down right. I don’t have any seams that are lifting away. Just the weird discoloration when it’s hot outside.

On 2018-07-08 by (mod) - closer look at browning seams on mod-bit roof

I see a darker color hue where layers of mineral-covered roofing overlap; that could be an artifact of having heated that area of the material or sealing it during its application. That's IF your mod-bit roof was hot-applied, not cold applied.

I couldn't see enough detail from your photos but one would look for a bit of run-out at the seams to confirm that it's a hot-applied roof. If there is absolutely none of that it may be a cold-applied modified bitumen system.

A hot applied modified bitumen roof can easily be over-heated during installation if the installer isn't experienced, especially when a torch rather than hot-air welding is used. The working heat can already be quite high, as much as 3000F.

I also noted in one of your photos a low spot that's dark, perhaps from debris accumulation when the roof is wet.

Temperature and moisture differences might well make heated seam areas show up.

On 2018-07-07 1 by John L. afternoon photos of modified bit roof showing seams

You can see the horizontal brownish lines along the seams on the hot day. Thanks for you help!

Modified bitumen roof life question - browning on hot days (C) Inspectapedia.com John L

The 3rd and 4th pictures of my modified bitumen roof - looking down over and below the concrete tile roof - (shown above) were taken at roughly 3:30 in the afternoon on a hot 100 degree plus day.

Modified bitumen roof life question - browning on hot days (C) Inspectapedia.com John L

On 2018-07-07 by John L. - Modified bitumen seams turn dark in hot conditions

The first two pictures (below and above) are taken at roughly 7:30 AM at around 60-65 degrees F.

You can see how there is some browning along the seams on the hot day. The discoloration goes away as it cools

Modified bitumen roof life question - browning on hot days (C) Inspectapedia.com John L

On 2018-07-03 by (mod) - diagnose brown discoloration near modified bitumen roof seams

John,

I'm not sure what's going on either although I speculate that there may be a color difference that varies depending on the moisture level on your roof.

It would be great if you could take photos of the different colors and document the time of day and conditions. You can post photos by using the add image button below the comment box.

On 2018-06-25 by John L

I recently installed modified Bitumen roofing (torch down roll) on a patio cover. I noticed some areas around the seams and towards the edges of the patio cover have a browning discoloration under the hot sun. It's been hot and 100 degrees.

By morning, the brown discoloration goes away. I'm curious about this. Any thoughts?

On 2016-08-20 by (mod) - plan to install cold-applied modified bitumen roof

Certainly there are plenty of roofers who wouldn't hesitate to add a layer of mod-bit, cold process, over an existing low-slope roof in good condition. Be sure the working surface is dry. Let the material lie unrolled to relax and flatten before adhering it.

On 2016-08-20 by Jim

I have a 1929 house with a low-slope roof onto which I want to install mod-bit roll roofing.

After reading numerous horror stories of low-slope roofing contractor failures, I've decided to do this job myself. I had successfully treated the existing roll roofing with fibered coating which, after several years, has begun to fail.

So, it's time for new roll roofing. Since my existing roof is solid I want to use it as a base, installing the new mod-bit roll roofing on top.

I know you prefer a torch-down install, but since I'm doing this myself I plan to use a cold process to install the new material.

This looks like a job that I should be able to do but, not having done it before, I'd appreciate knowing if I'm moving in the right direction.


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Continue reading at MODIFIED BITUMEN ROOFING - topic home, mod-bit roofing, sold in rolls and applied to low-slope roof areas can be mistaken for mineral-granule-coated roll roofing, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

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