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EPDM roofing question?

JsBach

I visited a building about ready to open today with a group from the office, including the project manager. I am not all that familiar with EPDM roofing and its installation. It was a mechanically fastened system and it had quite large sheets of material, maybe 10'x20' only fastened along the edges. It was a fairly windy day and the roof skin was raising up and flapping in the center, up to an inch or two. First of all how could this be water tight if that much air was blowing through it, and wouldn't the flapping action eventually wear out the roof. The project manager explained that it was a suction effect pulling up on the roof and this may be true. But there still had to be lots of air moving through as it would raise and fall quite a but. Is this roof installed right and is this standard on mechanically fastened EPDM roofs.

 
Nov 21, 07 7:44 pm
b3tadine[sutures]

EPDM roofs blow, don't use em.

Nov 21, 07 7:47 pm  · 
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binary

i was an inspector on epdm roofs for a few summers...


the insulation is screwed to the decking with perimeter and 1-2 rows down the centers.....

then the epmd is glued to the insulation

flaps/joints are primed and epdm tape is used

then j-rollered seams and the roof is rolled with a water weighted drum

it's not a hard process really......... only thing that sucks is when they tear out the old coal tar pitch roofs..... you cant breathe in the dust or get it in your pours...... the sun/heat causes a reaction and you'll get a burning feeling and some other issues

b

Nov 21, 07 7:55 pm  · 
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cryzko is describing a fully-adhered system; you're describing one that's just laid down and fastened.

i'm pretty comfortable with the former. perfectly good roof; makes a nice job. i don't know where you are but, for exactly the reasons you described, i would never use the latter in kentucky.

Nov 21, 07 8:15 pm  · 
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I love EPDM! My favorite song is 'Crossover'.

Nov 21, 07 8:22 pm  · 
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JsBach

Nice pun there [beta] v.4, it does blow leterally. Steven Ward you are right in that it its just layed down and fastened, and I don't have a problem with that per se. It was that it was only fastened at the edges of the very large pieces, and it flapped like a tent in the wind. I just can't see how with that much air could get under there with it still being water tight. And worse is we've all seen how fast flags wear out from the flapping motion, just because te roof is a tougher material doesn't mean its indestructable. Am I just crying wolf or is something really wrong here. Its not my project but I am still concerned.

Nov 21, 07 8:47 pm  · 
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binary

hence the glue...... spray both sides and let it setup then fold...easy


765...rampage/gold digger
http://www.youtube.com/results?search_query=epmd&search=Search


just take a pick... all good tracks


b

Nov 21, 07 8:55 pm  · 
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bronson, architect/assassin
Nov 21, 07 11:55 pm  · 
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some person

A loose-laid epdm roof requires ballast to hold it down from blowing in the wind. JsBach: your intuition is right, they probably haven't laid the ballast yet but soon will.

If you're really curious, ANSI/SPRI publishes a document that gives the requirements for single ply ballasted roofs.

If you're in Wind Exposure Category D (i.e. close to a large river or body of water), it is very hard to find a loose-laid system that complies with the requirements of the ANSI/SPRI document.

Another thing to consider - in addition to keeping the membrane on the roof - is also the fastening of the roof insulation to the deck. More fasteners are required for higher wind speeds - typically more in the corners and at the seams.

Nov 22, 07 9:55 am  · 
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JsBach

Thanks DCA, I thought about ballast but I'll have to ask the project manager if it is coming but I supect it isn't. I did some research on the Firestone web site and there are mechanically fastened, non-ballasted options. It was hard to find but I think you have to have staggered connections across the whole roof at 18", not just along the edges at 12".

I'm not sure what our wind exposure here is in Dallas (I should shouldn't I hehe) but it is a typically windy place with frequent thunderstorms. Yesterday was particularly windy as a cold front came through so we were able to see how the roof reacted.

I'm kind of new to doing building shells and don't know much about this stuff. I've primarily done design and interiors most of my career. And they certainly didn't teach this stuff in school. Maybe we should have spent a little less time building white study models and a little more learning about how buildings are built.

Nov 22, 07 11:40 am  · 
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mdler

when you go to inspect the epdm roof, be sure to wear your golf cleats

Nov 22, 07 3:34 pm  · 
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JsBach

Hehe, good one mdler.

Nov 23, 07 12:23 am  · 
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evilplatypus

they should still be fastening it in the middle and covering the fastenrs with patches for a 10' layout without ballast - or it should be adhered or ballasted

Nov 23, 07 1:04 pm  · 
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evilplatypus

here - this is a 10' layout from firestone - notice they provide center fastening along the perimeter of the membrane - your local rep could prob be more specific this layout is generic. link

Ive been on a lot of factory roofs where there are patches in the center between seems like 48" oc the whole field of the roof, each patch adhered to the roof covering the fastener, I dont know if its recomended but it works

Nov 23, 07 1:08 pm  · 
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evilplatypus

go to the bottom under BITS system 10' seams
[url=http://technicaldatabase.fsbp.com/technicalresources/attachmentguide/
link[/url]

Nov 23, 07 1:10 pm  · 
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evilplatypus

go to the bottom under BITS system 10' seams
[url=http://technicaldatabase.fsbp.com/technicalresources/attachmentguide/
link[/url]

Nov 23, 07 1:10 pm  · 
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bothands

the epdm membrane lifting up with wind is likely from negative pressure, not air getting under it -- the same way there is negative air pressure on the side of a building that is opposite the windward side (ala an airfoil)...

Nov 23, 07 4:38 pm  · 
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JsBach

Yeah bothands, I think it is negative pressure, but should it lift at all. Air must still be getting through somewhere to allow it to lift an inch or two off the deck. If that much air is getting through, I would imagine water would follow, its sneaky like that.

Nov 23, 07 5:40 pm  · 
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EPDM-Rubber

Liquid EPDM is much better than Sheet EPDM. See both types of EPDM https://www.epdmcoatings.com/e... and differences can help the make the right decision before installation.

Apr 3, 18 4:33 am  · 
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oliviacolewood

I watched this video before helping my dad lay our EPDM roof for the shed and we found it quite helpful. https://www.rubberroofs.co.uk/... It's a good job we took preparation steps otherwise I'm sure it could have ended badly.

Jul 5, 18 10:18 am  · 
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Volunteer

Obviously some steps were left out of the installation. I would check with the manufacturer of the roof sheets. They should be glad to help as they will gain a serious ding to their reputation when the sheets leave the roof if the situation is not corrected.

Jul 16, 18 8:53 am  · 
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MACV68

I've used fully adhered and loosely laid single ply membranes but not mechanically attached  I would think it would fail at the corners in a high wind.  Perhaps it's a matter of location.

For air to not enter under a lifting membrane, the roof deck would have to be air sealed which is not necessary even if it were possible.  Bulk water would not follow interior air movement   

You might ask the manufacturer to host a seminar at your office and get  some CE credits and a free lunch   

Jul 21, 18 9:13 am  · 
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curtkram

i don't think people use epdm very often anymore. tpo seems to be better in just about every way. look into rhinobond for mechanically fastened. i think carlisle or someone else has an equivalent.

Jan 28, 19 10:18 pm  · 
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MACV68

I just noticed how old this discussion is.  Small dimmed text is virtually invisible to old folks.

Jul 21, 18 9:25 am  · 
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