Vapour Control Layer to new concrete floor?

[bobthebuilder1000]

I am using Celotex 3000 (25mm) insulation below a new concrete floor on a very small scale job (new concrete floor in an existing cellar).

I am putting a 1200g DPM down first, then the insulation and then the concrete. Do I need a VCL over the insulation and under the concrete? ....

 

[PrenticeBoyofDerry]

The answers is yes,
a little guide for you.
http://www.sheffins.co.uk/pa_guide/Ground-Floor-Solutions.pdf

 

[bobthebuilder1000]

1. What happens if I don't bother?

AND/OR

2. Should I go: insulation - DPM - concrete....and lap the DPM up the side hard against the existing wall and then put some insulation (vertically) between the DPM and concrete around the edge?

Cheers.

 

[freddiemercurystwin]

The dpm should be positioned so as to keep damp out of the insulation so needs to go beneath. The VPL is really just working there to work as separation layer to stop the screed or concrete seeping into the gaps between the insulation boards.