I am rehabing an ‘L’ shaped porch on an old Victorian in N.Y.. The corner of the ‘L’ has a bumped out octagonal shape. Total area of ~700 s.f.. Although because of a large overhang on the main roof above that has a yankee gutter, the exposure to rain is probaly only 500 s.f.. The pitch is about 5/8″ in 12″. Very low. To simplify the owner and I decided to do away with the original built-in gutter and just slope the roof all the way to edge and install drip edge.
The porch has 10 columns and on the roof deck above each column I’ve anchored 6″X6″ posts to the plywood deck for railing posts. They will eventually be wrapped with trim after the roofing is installed, covering the flashing.
Couple of questions:
1. I’ve installed peel and stick membrane as flashing around the bottom 8″ of the 6″x6″ posts and along the entire outside 36″ perimeter of the roof as per Grace’s detail for skylights. Mistake? Will rubber roll roofing adhere to a product like Grace ice and water shield?
2. Should I install the drip edge onto the plywood deck or on top of the peel and stick membrane underlayment? My thought being it might be good to really secure the underlayment under the drip edge. I don’t want the peel and stick to lift along the edge. The horizontal dimension of the drip edge is 2 1/4″.
3. I am going to install two 4″ round copper drop tubes thru the sheathing and soffit and connect to downspouts. This is really only to handle the two leaders that drain part of the upper main roof of the house onto the porch roof. I was thinking of essentially ‘plugging’ the leaders into the downtubes. The drop tubes (down tubes?) are attached to a flat 12″ square flange that would sit on the deck. Should I attach directly to the plywood deck or overlap the peel and stick underlayment with the flange?
4. Should I provide for venting hidden behind the drip edge? The cornice is comprised of crown, fascia, bead board soffit to a boxed in beam, and a full bead board ceiling under porch. Although it is not over an interior space, the roof system is enclosed. Is it better building practice to allow for air in and out?
Thank you much, Mike w
Edited 3/21/2008 10:30 am ET by jdevil
Replies
Greetings j,
This post, in response to your question, will bump the thread through the 'recent discussion' listing again which will increase it's viewing.
Perhaps it will catch someone's attention that can help you with advice.
Cheers
Peach full,
easy feelin'.
I'm confused Mike. You said "rubber roll roofing"; do you mean a EPDM aka rubber roof? If that's the case, you don't need ice and water shield. You normally glue the rubber onto some type of substrate--fiberboard, plywood, or even OSB. There are probably different ways to go about it, but the way I was taught was to bring the rubber over the edge of the roof and then nail edge flashing on top. The flashing then gets covered by cover tape, which welds to the rubber and is applied to the flashing with contact cement. Posts would be harder to deal with, though they could be flashed with flexible flashing used for outside corners and terminated on the posts with termination strips. That's how I'd do it with rubber, though again, I'm not sure that is what you are talking about.
Not sure about the Ice and Water under the rubber. I would get it off of there because I would be concerned what would happen when the solvents in the contact cement hit it.
I'm going to go with a bituminous roll roofing . I have to look into installation procedures as far as base sheet, etc.. There will be a trimmed wood sleeve with cap that goes over the 6"x6" posts that get the flashing.
Good to jknow OK to install drip edge over underlayment.
Thanks for the reply.
What I posted applies to EPDM (rubber) membrane roofs. I might have given you a bum steer, as I'm not really familiar with the product you are using.
may want to check the specs on that bitumen sounds like your 5/8" in 12" may be lower than allowed----especially with roof penetrations
Me-- i would EPDM it---which wouldn't be compatible with the Grace you already put downTry--grace on the whole deck---then screw down insulboard underlayment and EPDM over that ?still wouldn't be happy about the roof penetrationsStephen
That's the way I'd do it
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