Concrete floors

Hard@work

Do you place the vapor barrier over crushed rock or under crushed rock?

stuart45

I would put over the top, over a bed of sand binding as well to protect it.

Canucker

http://www.buildingscience.com/docum...flooring-probs

Skip the layer of sand , no need for it.

stuart45

Depends where you are. Building regs here insist on sand binding over hardcore to stop any punctures of the slab.

Canucker

True, building regs. do tend to lag behind in some areas of code

stuart45

Looking on that link they were talking about sand on top of the vapour barrier, which doesn't make sense. However without sand underneath the DPM there have been problems with damp coming through where the hardcore has punctured the plastic. Depends on how damp your climate is.

Canucker

If I'm interpreting it correctly, the crushed rock is a drainage layer, followed by vapour barrier, then the concrete. The only problem that a hole gives it, is that you would have vapour diffusion the size of the hole through the concrete. Standing water under the slab would wick through it though, which is a completely different issue.

itsreallyconc

ohfercrhssakes, quit arguing back & forth just use 15mil vb & be done w/it,,, we use no sand under OR over our vb nor have we ever,,, then again, we never place conc over only a crushed stone base

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if you hear it from a guy in the apron store, be VERY suspicious the mtl/method will work,,, when it time to build something together, they won't answer phones NOR help
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cleveman

Yeah, I put a vapor barrier right on top of the rock and pour the concrete on that.

jomama45

You're not supposed to be pouring concrete in your golf cleats Stu......

Here, we pour directly over the VB, being cautious not to puncture it. Plywood strips to wheel on & concencious workers goes a long ways.

stuart45

Thanks Joe, I know where I've been going wrong now