Pitched To Flat Transition

reveivl

What's the accepted method for this transition? I'll be using a two ply torch-on on the flat with arch lams on the pitch. Run the glass base up the pitch, I&W, 30# ? The 'flat' will actually be 1:12. The pitch is 5:12. Thanks guys, Rich.

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MJW

I would use a valley tin or some strong metal. Some don't use anything, just run the shingles down onto the torch down. I would be more comfortable with some metal in there.

RooferJim

Run the flat roofing up under the transition a min. 24" under your shingle coursing its also a good idea to nail of the top of the plies with buttons then overlap it with the shingle underlayment whether it be felt or I&W. metal base flashing is really only good if its put on by a good metal man and has locked and solderd joints "fully sweated and laced with properly heated irons". You can always tell a real cornice man by how he solders.

RooferJim

www.jbennetteroofing.com

AaronB.

Is it a two ply torch system, or a one ply base and one ply torch?

If it is a one ply torch, then run the filed sheet up six inches onto the shingle area, then flash the transition with another piece, laying six inches on the low slope and the rest of the sheet up the steep slope.

If you do not have extensive experience with torch systems, I wouldl suggest hiring a licensed, insured pro to do this part of the work. Be careful, as most "construction" type policies do not cover open flame work. There is a very real and serious risk of fire in this scenario.

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reveivl

Thanks for the input guys,it will be a one ply base, one ply torch, that's the system I'm familiar with. Aaron, when you say "then run the filed sheet up six inches", what are we talking here, the base sheet? both? I get the six inch part, just the layer I'm not clear on.

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reveivl

Never mind Aaron, just went out for a smoke and got what you're saying, thanks, Rich.

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AaronB.

Yeah, run the base up to the termination point of the flashing.

Doing it this way and getting the sheet membranes tight to your transition will give you a double layer in the transition and a nice solid flashing of said transition.

BE CAREFUL...YOU CAN BURN YOUR HOUSE DOWN WITH THIS SYSTEM!

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Grumpy

I'd run the flat membrane up the pitched section at very least 1.5'. I would then overlap that with my ice shield covering about 1' of the overlap, assuming ice shield is compatible with the roof membrane because some are not (EPDM). I would then continue with my regular 'ol 30#, I would then NOT want to shingle all the way down, just just enough to cover my ice shield and maybe one coarse of shingles below the ice shield.

This is how we've been doing it for years and never a problem.

reveivl

Sorry to beat this point to death, fellas, but...

So I do it like Aaron says and wind up with two layers of torch-on in the transition, the upper one extends up the slope about 30". No problems here, that makes sense. But then I come along and start nailing archs level with the transition? So now I've got nail holes all through it about 5" up? I guess this is where the I&W comes in, can you use that stuff over the torch-on? Am I just being paranoid and should just go ahead and do it? Tks, Rich.

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fettycan

yes

reveivl

: "Yes" what?

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fettycan

I&W over and nail on your shingles. ( paranoid ) no just concerned
when you shingle across this part you still need a double row to cover the ends where the shingles butt together and yes just go ahead and do it

AaronB.

I would clean the talc off the surface of the modified if youre going to use the Ice barrier to get better adhesion, but I actually would leave a course or two out at the tranistion to make sure there would not be fututre problems.

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reveivl

Thanks for the help, guys, got the torch-on down, glad it's my place, 'cos I don't think I'd be happy with trying to sell this to a customer. It's not gonna leak or anything, but aesthetically it leaves a little to be desired. Particularly where the flat roof meets the valley, what a nightmare to get the torch-on to lay down flat w/o wrinkles. If I ever get a contract for this I'll be subbing it out and watching.

Aaron, I like the idea of starting the shingles up a course or two, that makes sense, what's this talc that you're talking about? Anyhow, tks again for helping me through that, I'm back on familiar ground now. Rich.

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AaronB.

Well, if it is a smooth surfaced material, most of them come with a talc on the surface to prevent the bitumen from sticking together.

Granulated does not.

Does your modified look like this?

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reveivl

Can't tell from that pic, but mine has the granules, so no talc, I guess. I'll start my shingles up two courses over a layer of I&W. Rich.

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Grumpy

Some manufacturers have details for this at their websites you may also want to check out the manual at www.nrca.net

AaronB.

You can click on that photo to enlarge.

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