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Small Cabin Forum / Cabin Construction / Low Pitch Roof - Membrane or Standing Seam?
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mark11
Member
# Posted: 29 Aug 2022 14:17
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Im debating whether to do a EPDM membrane roof or standing seam for my garage roof because I was only able to get 0.57 pitch. It will attach to logs as you can see from picture.

I would rather go with standing seam but I was told its better to go with membrane roof to avoid future leaks. Im in climate zone 5 and it snows a lot so metal roof would be easier for snow to slide off. Thanks
roof1.jpg
roof1.jpg
roof2.jpg
roof2.jpg


Brettny
Member
# Posted: 29 Aug 2022 14:33
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With 0.57 pitch the only thing sliding off is going to be rain. I dont believe stand seam works at that low of a pitch.

With your climate zone I would have seriously though more about this considering this is a new build. Since your this far along alreaty I would loose those windows or make them smaller and do a 3/12 pitch. 3/12 is the lowest for standard metal roof or shingle.

mark11
Member
# Posted: 29 Aug 2022 14:50
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Quoting: Brettny
With your climate zone I would have seriously though more about this considering this is a new build. Since your this far along alreaty I would loose those windows or make them smaller and do a 3/12 pitch. 3/12 is the lowest for standard metal roof or shingle.


Making the windows smaller is not an option. Its either EMDM or standing seam basically. Which do you think would be best long term ?

gcrank1
Member
# Posted: 29 Aug 2022 20:59
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Even EMDM covered flat roofs seem to eventually have issues. That doesnt mean that maybe they could/should have used standing seam.....

spencerin
Member
# Posted: 29 Aug 2022 21:03
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What's going on the roof of the main structure?

mark11
Member
# Posted: 29 Aug 2022 21:27
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Quoting: spencerin
What's going on the roof of the main structure?


Standing seam roof.

spencerin
Member
# Posted: 29 Aug 2022 22:34
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Opinion here, but I'd go with standing seam. Match your main roof, and it has to offer *some* structural advantage over a rubber coating, especially in a snowy area.

ICC
Member
# Posted: 29 Aug 2022 22:35 - Edited by: ICC
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Standing seam roofing can be used on pitches as low as 0.25/12 but to do so the substrate must be hydrostatic not hydrokinetic. That is to say the roof substrate must be able to have standing water on it and not leak. Extremely low pitches with a wind blowing up the slope can accumulate a build up of water; nothing really running off while it rains.


I would not be happy with such a low pitch in most places where it is cold enough to snow. Snow will not slide off that no matter what type of roofing. Snow may blow off, then again wind may cause it to drift and pile up against that wall. It will melt when it gets warm enough. People around where I am sometimes need to shovel snow off their low pitch roofs to head off structural failure. That would be a concern of mine.

Brettny
Member
# Posted: 30 Aug 2022 05:17
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Quoting: mark11
Its either EMDM or standing seam basically. Which do you think would be best long term ?

Long term in snow country none of those options are good long term.

Was the garage an after thought? How was this drawn in the original plans?

mark11
Member
# Posted: 30 Aug 2022 08:55
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Quoting: spencerin
Opinion here, but I'd go with standing seam. Match your main roof, and it has to offer *some* structural advantage over a rubber coating, especially in a snowy area.


That is my exact thinking too. With standing seam if any snow up there I can easily push it off the roof easily. My concern is flashing area where it attaches to the logs and want to avoid any log water damage since its hard to attach as it is.

mark11
Member
# Posted: 30 Aug 2022 09:04 - Edited by: mark11
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Quoting: ICC
Standing seam roofing can be used on pitches as low as 0.25/12 but to do so the substrate must be hydrostatic not hydrokinetic. That is to say the roof substrate must be able to have standing water on it and not leak. Extremely low pitches with a wind blowing up the slope can accumulate a build up of water; nothing really running off while it rains.


I was thinking of adding ice water underlayment like this. Do you think thats sufficient as a hydrostatic substrate? Or do you suggest other material. Thanks very helpful

spencerin
Member
# Posted: 30 Aug 2022 11:08
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They're exterior-facing logs, designed to be exposed to the elements. I wouldn't be worried about water damage to them, just make sure the flashing doesn't trap water against the wood.

mark11
Member
# Posted: 30 Aug 2022 11:09
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Quoting: spencerin
They're exterior-facing logs, designed to be exposed to the elements. I wouldn't be worried about water damage to them, just make sure the flashing doesn't trap water against the wood.


Do you think its ok to go with metal roof ?

ICC
Member
# Posted: 30 Aug 2022 13:52
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Quoting: mark11
I was thinking of adding ice water underlayment like this.


That is great stuff. Grace makes the best sealing products. There is a temperature range for best stick. Stay well within that.

NorthRick
Member
# Posted: 30 Aug 2022 16:57
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Heck, make it a deck and turn one of those windows into a door.

ICC
Member
# Posted: 30 Aug 2022 19:17
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That's an idea. Do the gentle slope for having water run off and frame a deck above that. Use deck boards in squares that could be lifted out for whatever reason may arise.

rockies
Member
# Posted: 30 Aug 2022 20:55
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This article may help.
https://www.westernstatesmetalroofing.com/blog/low-slope-metal-roof-panels

mark11
Member
# Posted: 31 Aug 2022 12:20
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Quoting: NorthRick
Heck, make it a deck and turn one of those windows into a door.


That was the idea but may have to do that later. For rubber roof I was quted 9K which is insane.

mark11
Member
# Posted: 31 Aug 2022 12:21
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Quoting: ICC
That's an idea. Do the gentle slope for having water run off and frame a deck above that. Use deck boards in squares that could be lifted out for whatever reason may arise.


The only slope i can get is 0.57 so Im thinking this might be better than EPDM roof which will hold snow longer till it melts. At least with metal Im able to push it off easily.

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