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EPDM or TPO roofing material as crawl space vapor barrier?

EPDM or TPO roofing material as crawl space vapor barrier?

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  #1  
Old 03-14-17, 08:06 AM
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EPDM or TPO roofing material as crawl space vapor barrier?

So I've had a few contractors come out to give me a quote on crawl space encapsulation (sealing vents and installing vapor barrier on the floor and up the walls), and I'm getting outrageous quotes. So i'm thinking about tackling this one myself.

In my quest for material, I've found a source of potentially getting enough leftover EPDM or TPO roofing material to do the job (for dirt cheap or free). The companies that have come out are obviously suggesting 12-20 mil vapor barrier material, and I understand EPDM and TPO roofing material is typically 40-80 mil. Given that its cheap or free, and the fact that I go in the crawlspace a lot (storage, etc) it seems to me a no-brainer to use this thicker stuff. However, I cant find a lot of info on people using these in a crawl space. I've found a few forums where people said they used EPDM, but cant find anything on TPO. Seems TPO would be nicer given that its white, and EPDM is black, but EPDM probably a lot easier to do the seams.

Any comments or thoughts on this? Any negatives you can think of or know of anyone using either of these materials as a vapor barrier? Seems to me if they keep a roof dry, they would work fine as a vapor barrier.
 
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Old 03-14-17, 09:42 AM
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I have used epdm in several crawl spaces and been very happy with the installations.

The material lays out very well and fast compared to 6 or 10 mil poly. I never bothered to seal seams as vapor drive through a barrier is a lineal function and pressurization from below the barrier should be non existent to minimal, therefore the driving force to any seam overlay is not a factor in my opinion.

You can seal the seams in the traditional manner or just tape them but I don't really view it as necessary.

The use of this material makes moving around in a crawl space with an irregular surface much easier due to the cushioning effect.
 
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Old 03-14-17, 10:22 AM
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calvert, thanks for the response. This gives me confidence in using EPDM. The guy told me he could probably get me TPO material easier. Do you have any thoughts on using it? I understand normally on a roof, the seams on TPO get sealed with a heat weld. But in a crawlspace I wonder if I could just use Seam sealing tape. I think i'd rather seal than not seal, as i'm encapsulating it and have water that often gets on the floor after rains. I have french drains that go through there that handles the majority of it, but I've had humidity problems, so I'm trying to tackle it and have it handled long term.
 
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Old 03-14-17, 10:29 AM
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If you're in and out of the space frequently, is pouring a concrete floor reasonable?
 
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Old 03-14-17, 11:34 AM
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There actually is a concrete slab on the portion that I walk on most of the time. But the whole space is almost 1700 square feet, so concrete over all that wouldnt really be feasible.
 
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Old 03-14-17, 02:10 PM
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I haven't had a lot of experience with TPO membranes other than to handle samples of it. TPO hasn't been around nearly as long as EPDM and from speaking to roofing friends I have, I know the formulation has been changed several times. If you are getting some material that is older stock that may be considered an obsolete formulation, you may want to take into consideration your desire to weld the seams and keep a sealed assembly. You might ask your source for his opinion as to whether the stock he is providing is viable with regard to extended durability and ability to hold the seams.
 
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