Are all underslab vapor barriers the same?

[CudaA39]

Beginning stages of a 30'x50' pole barn in East PA, starting to collect odds and ends. Originally just planned to do a basic Menards/Lowe's 6mil for underslab vapor barrier (along with 2" XPS), but went down the rabbit hole of all different vapor barrier manufacturers and thicknesses.

Are all 6mil USA made vapor barriers pretty much the same? Seeing prices from $89 to $160 for a 20'x100' roll, not sure if theres a quality difference to pay attention to.

Eventually got to the Stego website and their 10mil green rolls, and began overthink what I'm trying to accomplish, which is basic vapor protection.

Is this a "get what you pay for" area or a keep it simple stupid area?

 

[ConCretin]

If the goal is simply to limit moisture intrusion into an interior space then a vapor retarder such as polyethylene sheeting is probably fine but if you intend to apply a moisture sensitive floor covering such as epoxy, a true vapor barrier such as Stego is a better choice. Some products simply let more water vapor through than others.

The other benefit to a 15 mil product such as Stego is that it is far more durable. Poly is likely to be poked full of holes by the time all the work is done greatly reducing it's effectiveness. Stego is both thicker, stronger and will take a lot of abuse.

Of course this all depends on how much moisture you have in your soils. If your soils are dry, you might not need anything at all. In addition to cost, there is a potential downside to vapor barrier in the hands of an inexperienced or incompetent finishing crew. Since the membrane under the slab will block bleed water from entering the soil, it has nowhere to go but up. Excess water on the surface of your slab weakens it and can lead to a range of surface defects such as crazing, blisters or de-lamaination.

 

[formula388]

I built a small garage (500sf) and I ended up doing 4 layers of the 6mil, my reason was I had to buy a 100ft roll so I might as well use all 100ft of it. I also then put 2" xps (pink) foam on top of that because I was doing in slab heat.
I made sure there were no holes poked in the vapor barrier by putting it down myself and then adding the foam on top which was the surface that the concrete guys walked on. I dont know if 4 layers of 6mil is better, worse or the same as one layer of 15mil... but at the time it seemed like a good idea.

 

[CudaA39]

Thank you for the feedback. I don't really have "set in stone" finishing plans yet, but I don't want to get years down the road and be overly restricted or regret not doing something now. A Stego rep called me back today and even though my project is definitely on their small side, he chatted with me for awhile which I appreciated it. I'm going to go with 2 of their 12'x75' rolls of 10MILL which will work out well for size.

 

[joes169]

I like using this stuff when we're looking for something stringer than typical poly. It's still only 6 mil, but it's far stronger and less likely to get holes in it.

Silage Tarp 6 Mil Black & White Covering | Farm Plastic Supply

Shop Farm Plastic Supply for top-quality silage tarps that are used for silage piles as bunker cover sheeting made from premium-grade polyethylene resins.

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[RivennHewn]

Visqueen is 1970’s technology

Under Slab Vapor Retarder - Underslab Vapor Barrier | Reef Industries

Griffolyn® under-slab vapor retarders prevent moisture from migrating and causing deterioration of flooring adhesive, warping, and more. Call today!

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