Devil_bri

But is there not a chance of damp degrading the insulation. I’m using kingsman tf70, 100mm ??

That does make sense

No not interested as internal floor area is under 30sqm, made of incombustible material and not used to sleep in.

I’ve googled the life out of this and can’t find the info I need, I’m sure it’s out there but I can’t find it…. I have the foundation in for a 7mx5m block garden room, with 100mm cavity. It falls under permitted development so no need for PP or BC. I am about to get the footings put it then I will fill the floor with the usual hardcore, sand, DPM, 100mm insulation, anther sheet of the DPM and then 100mm concrete. Which layer of DPM do I need to tie in with the dpc on the walls, the bottom or top layer or both ? thanks