New concrete floor

Posted by fredy on November 17, 2006, 4:08 pm

I am just about finished digging out my barn floor.

I intend to lay gravel, sand, damp proof sheet, insulation (polystyrene),
about 4 inches of ready mixed concrete with steel work.

My question is at what level/order do I place the polystyrene insulation and
what are the benefits of its location.

Thanks for any info.

fred

Posted by Art Yokell on November 17, 2006, 5:03 pm

Fred:

The polystyrene should be placed on top of the vapor barrier and the
concrete cast upon the insulation. The reason is that the purpose of the
vapor barrier is to prevent moisture from being forced into the insulation
under the pressure that is created by the temp. diff. Bring the vapor
barrier up the sides if possible and lap the joints by about 12-18". Your
reference to the damp proof sheet, I asssumed to be the vapor barrier. You
should try to use 10 mil Visqueen but at least 6 mil if you can't find the
10 mil.

>I am just about finished digging out my barn floor.
> I intend to lay gravel, sand, damp proof sheet, insulation (polystyrene),
> about 4 inches of ready mixed concrete with steel work.
> My question is at what level/order do I place the polystyrene insulation
> and what are the benefits of its location.
> Thanks for any info.
> fred
>

Posted by SteveF on November 17, 2006, 6:01 pm

Vapor barrier under insulation.

Not all insulation board is rated for under slab use. Check the
manufacturer's web site and make sure yours is.

Why are you putting down sand?

Steve.

Posted by Italian Mason on November 21, 2006, 4:22 am

> Why are you putting down sand?

Sand should be put down under a vapor barior and on top of it
under to ensure the plastic is not torn on the jagged base and on top
so the concrete doesnt go off like a rocket while finishing it.

SteveF wrote:

> >I am just about finished digging out my barn floor.
> > I intend to lay gravel, sand, damp proof sheet, insulation (polystyrene),
> > about 4 inches of ready mixed concrete with steel work.
> > My question is at what level/order do I place the polystyrene insulation
> > and what are the benefits of its location.
> > Thanks for any info.
> > fred

> Vapor barrier under insulation.
> Not all insulation board is rated for under slab use. Check the
> manufacturer's web site and make sure yours is.
>
> Why are you putting down sand?
>
> Steve.

Posted by Wayne Whitney on November 21, 2006, 12:13 pm

> Sand should be put down under a vapor barior and on top of it under
> to ensure the plastic is not torn on the jagged base and on top so
> the concrete doesnt go off like a rocket while finishing it.

By "go off like a rocket", I assume you mean set up really quickly. I
thought that pouring conrete directly on a plastic vapor barrier
typically delays the setting up of the concrete, as there is nothing
to absorb the excess water used for placement. The sand layer on top
of the vapor barrier would provide a more normal setting up time, as
it can absorb some of the excess water. Have I got this backward?

Thanks, Wayne

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