Oz07

Atleast you've always got a back up if the immersion fail.

Sounds like your job has become a bit of a battle for the bco. It's a tough one. Maybe in the first instance copy your piling engineer in on their concerns and get him and them to sort it between them. You want to try to de escalate if you want to get the job moving might need some skillful diplomacy when talking to both sides.

Sounds good what made you do this is it quicker recharge than ashp?

I'd just fill them with intumescent mastic.

Yes. Or even if 25/50/75 mm etc below you can use a sacrificial layer of eps to bring you up to level. I say sacrificial but obvs would be part of your floor insulation.

Yeh I've seen site bashers literally use a garden fork and spade to mix it up in a big tub. I think as dry as you can have it while still workable for board adhesive.

I'm also terrible at wet trades. I think a lot of the skill is getting consistentcy of the mix right whether it be mortar, adhesive etc etc

I find a bucket trowel easier to throw dobs on.

You can if everything is in course. I've done it myself before ontop of b&b with a spine wall. You just lay ontop of the membrane

This is what I am asking why cant it be done like this? Think @ETC is saying similar?

Mix a blob of adhesive up, dab a bit of board on and try to get it off in a week. No prep required usually. If excessively dusty give it a brush. I certainly wouldn't be wetting it immediately prior. Might be hard to dab the boards to a straight edge

How deep can these radon membranes go. Is there any reason they can't go flat below the insulation layer and just end up with membrane spanning the whole envelope of building. No corners etc. Any spine walls laid on top.

No brainer then I'd have thought. What's cheaper a system boiler or ashp? What does your estate agent think buyers would prefer?

I still don't think penetrations in the main fire stop ceiling would be good. Probably have to fill the gap between board and light with intumescent mastic. What about standard pb double boarded. 15mm if nessecary.

The building in question already has permission to demolish from current approved planning. That's why I can't see how they could require a new survey as you could knock it down currently on existing permission.