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.
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? ....