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TOPIC: Flat Roof

Low Slope Roof Details

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Hi - Experts I need some advise here. I have designed a small boathouse and guest suite for a project on the Ocean in Washington. What I have proposed is a very low slope copper standing seam roof. (Pictures are attached) The slope is 1/8":12 here is the proposed assembly above the sloped plywood sheathing. -Roof insulation is closed cell foam, (non Vented) -1/2" Pressure treated plyood sheathing -sloped to scupper -3/4" x 5.5" PT wood Battens @ same spacing as Standing seam running in same direction as standing seam (canted at edges) -Canted wood Battens at edges of Valley Flashing locations Paint on Waterproof membrane over entire roof incuding battens(CIM 1000) -Valley flashings are secure up and over the Valley Battens and fastend to the top of the Batten with a gasketed fastener. -Standing seam copper roof assembly over entire roof, -support cleats for the SS roof are located on the battens and are set into a wet application of the liquid applied membrane material -fully feild sealed standing seams, and all panels are continuous in length. (ie, No joints perp. to slope) -Provide sealant / caulding bead of Asphaltic material to tops of Valley Flashing on Battens prior to securing standing seam roof over this area. -Note entire roof slopes towards a large exterior scupper, so there should be no chnce of Ponding. the idea is, the liquid applied membrane is the waterproof roof, and the standing seam roof is also a fully waterproof roof, so in theory, if any water gets past the Copper roof, the secondary membrane will deal with it. Here is my question / Problem no roofers in the area will build or warrenty it as designed. they tell me the minum roof slope they will do with a standing seam roof is 1/2:12 I tried to convince them that the SS roof was an Architectural finsh over the Liquid applied membrane, but they are fearfull of all the penitrations. I have tried to raise the penitrations off the roof with the battens, so if water is pooling under the metal roof, it will not be pooling around the penitrations. Any advise will help. and sorry for such a long message.
Eric Pettit

9/11/2006
Wow. You have obviously put a great deal of thought and work into this. What you are talking about would have to be a field-seamed or hand-crimped roof system for that low of pitch. Fact is, it is below what is considered to be a minimum pitch and there may be dependence on the roof system underneath. I still do not know of any manufacturer or contractor who will provide a leakproof warranty in light of that. You may get someone to warrant that they did everything to your specifications and then the onus for performance is on your specifications, not the installer.
Todd Miller
Isaiah Industries, Inc.

9/14/2006
Thanks Todd I feared someone would say that. What I wanted to hear was "Wow, your idea seems foolproof, and as an expert, I say I full support your use of the specific meterials" Or "I fully support what you propose, the Membrane below is the actual roof and the metal roof would be an architectural finish, It looks like it wil work perfect." Ha ha ha But your answer does shed some light on some options. If I can convince my client to trust me, and am willing to accept the consciquences if something goes wrong. Any advise on who I could talk to about somethng like this. Has anyone out there used a Liquid Applied membrane like this before.
Guest User

9/15/2006
Can someone explain to me why a fully soldered, or hand seamed metal roof with full length panels from top to bottom (no horizontal joints) would not work in such a low slope. Is there something I am missing. I suspect the problem area would be in the Valleys where the various roof slaopes converge, but I feel my Batton solution would raise this potential problem area out of the danger zone, and with the huge 2' wide "waterfall" scupper we have designed, there should be no risk of water pooling up there. thanks for the assistance
Guest User

9/15/2006
What gauge roofing panel would you guys recommend for a metal roof that is not in contact with the sub-roof, but is actually suspended off the substrate on its clips, but still is strong enough to walk on (for maintenance)
Guest User

9/15/2006
It could indeed work if it is folly soldered and you may get someone to warrant their installation of that sort of hand-crafted product. As far as walkability ... you may need to look at metal that is at least .024" thick in steel and potentially thicker in copper or aluminum.
Todd Miller
Isaiah Industries, Inc.

9/23/2006
Eric, sounds like a well thought out roof system. Use of copper due to the location is a good idea. No endlaps a good idea because of the low slope. However, the slope is below this industry's manufacturer's 1/4 to 12 recomendation. I don't know how large your roof area is, but at an 1/8 to 12 slope you will have water ponding on it. I would suggest you inquire with the panel supplier regarding their thoughts on ponding water, even though it is copper....just a suggestion
Guest User

9/23/2006
Thanks.
Todd Miller
Isaiah Industries, Inc.

9/24/2006
Thanks Fellas, SO I did not tahnk you all sooner
Guest User

7/3/2009
Sure. All best.
Todd Miller
Isaiah Industries, Inc.

7/3/2009