Conor

Stop the leak and park a dehumidifier there for a a few days. Quite possibly do more harm than good lifting the boards.

You assume the role of PC. Just update your documentation etc.

Thick carpet and underlay are your friends here. Job will be done and dusted this time next week and your house will be warmer for it.

We've carpet, towels, LVT and 14mm laminate. All works well. Apart from the but under the 1" thick wool rug 🤣

A weed membrane will stop the roots of any weeds getting down into the soil. But, by that point the plants will be big enough to be a nuisance anyway, so not a huge benefit.

Pipe needs to be straight and not pulling, these things leak easily, I've installed 100s of them. Strictly speaking, this is the property of the water company and you shouldnt be touching them, better option is to call them and say their meter box is leaking.

It'll just be an old clay pipe running in to a ditch. If in doubt, budget on a full new treatment plant and soak away / discharge and get it taken off the asking price.

Unless you were face into it with a grinder, drill etc with dust flying everywhere, there's almost no risk.

Only way to know is to get a sample tested. Plenty of companies offering that service. May as well do it and know for next time. But if it's all now sealed / covered up, then there is no point going back in at this stage.

I can't remember. Long gone from that house now. I think my spark supplied and fitted it, but almost sure it was a standard dimmer.

Yeah, pretty loud on the outside. Rarely ran mine full tilt. Yes, just ripped all the fan stuff out of the cheap hood I got from Currys.

£200-£500k That's assuming 250mm thick reinforced concrete. Allow about £1k per m2. No allowance for drainage, edge protection, access, egress etc.

I fitted the dimmer along the supply to the unit. I ripped everything out of the hood and dumped it, everything except the lighting went to the Monsoon unit outside. So two power supplies, one to the Monsoon via a dimmer, and another to the hood just to power the lights.

Something like 50mm eps glued to the inside would probably be enough. And lag the pipes.

You'll need continuous ventilation for the pitch roof at a minimum.