How to Transition from Metal Roof to Mod Bit flat roof

Cathy Grondin
8/7/2014
I am reroofing a 3:12 pitch roof to Metal standing seam. I have a small flat roof addition off the back and it is flat, no pitch. i have torn off the old rolled roofing of the flat as well. This is my first attempt at roofing and i have read endless amounts of metal manufacturer installation guides. I have applied the mod bit underlayment on the flat roof up to and extended onto the pitched roof slightly. Then i tied in the metal high temp underlayment on the sucessive row. I'm not sure of the best way to tie in the metal to mod bit rolled roof. I was thinking of flashing the transition. Under the metal panel and over the rolled roofing. Unsecured on the rolled roof as i do not want screws . But i don't want to create a neg flash on the flat roof as i have read here Roll the mod bit on top the flashing transition slightly onto the pitched roof and then overlay with metal panel. Do i end the panel before i hit the flat roof transition. I
Todd Miller
Classic Products, Inc.
8/7/2014
You do need a flashing that goes up the steep roof and ends up tucking under the underlayment, and the out on top of the flat roof. The brake for the pitch change needs to occur high enough on the steep roof that it does not create a negative pitch.
Guest User
8/8/2014
I have already installed the underlayment on the both the pitch and flat roofs. Everything i read says flashing goes over the underlayment and under the , finished product. From my interpretation i should have flashed under the undelayment of the pitched roof? Since it is too late , can i flash up under the metal panel and over the finished cap sheet of the flat roof
Todd Miller
Classic Products, Inc.
8/8/2014
Um, not everyone would do it this way but I'd like to see an extra width of underlayment worked in that goes under the higher underlayment and out on top of the flashing so that if any water / condensation ever comes down the underlayment, it ends up on top of the flashing. Again, not everyone would do it that way so it's probably not a huge risk if not.
Guest User
8/8/2014
I used a self adhesive underlayment, there is no way to go under the higher pitched underlayment. The installation guides i have seen for metal panel have a transition flashing installed after the underlayment and under the panel and that is why i laid it down first. perhaps i need to work in the flash and apply another row of underlayment over it? I know i will have a negative crease but not sure what else i could do. I am now thinking of going to the metal shingle as i have the flared gable as you call it.
Todd Miller
Classic Products, Inc.
8/8/2014
With having used ice and watershield, I think you're okay to continue as you area. It's sort of paranoia on my part that makes me like doing is the other way. It is not essential though

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