Lars P

found this on LABC https://www.labcwarranty.co.uk/technical-blog/damp-protection-for-concrete-floor-beam-systems - but their website is nowhere to be found

It's actually not Radon driving this palaver, but the fact that there is an old landfill 245.5 meters away from my front door - so my house is in the 250m 'buffer zone' - even though the extension in the back garden will be by 1m2 or so. Talking about measuring elastic band with a caliper So did you do something along these lines - just with the insulation and the slab swapped around - and then 100mm out though the foundation - and the membrane through the foundation as well ?

Great - thanks Redbeard - let me try pick your brain. First of all - the main house has no gas protection whatsoever - only a not very tight fitting DPM over the block and beam floor, - so seems somewhat pointless having to go through the effort of protecting the extension as it will be one big room. Anyway. Below is the design so far but I seem to have an issue with the anchor bolts penetrating the membrane. Also - I'm unclear how the membrane should be finished off where it meets the outside wall of the main house. Any ideas ?

Hi diyers and pros Does anybody have experience in with this topic.

Born with the 'I can do that' gene. How hard can it be. We'll, it's not just old fashioned logic and pragmatism all the way. Started out with a simple design, now having to build Fort Knox.