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Re: Slab on Grade and the Green Code

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Hello Oshin & Board:

Have you been able to get any information on why the GBC wants
no sand over the vapor barrier?  How do the writers of the GBC
expect the concrete to be installed without puncturing the typical
plastic sheet, 0.006" thick, that is used as a vapor barrier?

I'm sure that you know this, but the sand is used over the gravel/base
to protect the underside of the plastic and it's used over the plastic
to protect the plastice from puncture from workers stepping on
the large aggregate in the concrete while placing and screeding the

It would seem that the negatives of puncture, e.g. allowing vapor through
the barrier, outweigh the benefits of not using sand to protect the 

I would be curious to know what the creators of the GBC have to say on
this issue.

Take Care,

On 5 Dec 2013 at 8:15, Oshin Tosounian wrote:

> Does anyone have a resolution to a conflict between the Green Building
> Code
> and the standard slab on grade base requirements, usually recommended
> by
> the soils engineer? The GBC requires the concrete to be placed
> directly on the vapor barrier which is directly placed over a 4" base
> of gravel. The standard practice and most soils engineers'
> recommendations is the placement of concrete over a sand base with the
> vapor barrier in the middle
> of the sand layer, then the gravel base.
> Oshin Tosounian, S.E.

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