How do I bathroom / kitchen / extension? etc.

It was for underfloor heating.
I believe it was near 100mm of wheelbarrowed sand cement screed.

It was totally off limits for 2 days, and we had some first fix electrics the following week (approx 5 days after).
No flooring or kitchen units advised for at least 40 days, longer the better subject to temperature and humidity.

We got roof, plumbing and electrics etc sorted in the meantime, but with summer holidays it meant that it was about 80 days between doing the screed and installing kitchen and flooring.

The structural concrete part of the room (old kitchen diner) was usable a lot quicker, but did benefit from latex self level after.

I have some cute cat paw prints in the screed where there was a bit of exploration going on.

Our existing house was built on a concrete beam and EPS system, so the existing kitchen diner area had to have UFH embedded in a structural concrete slab. This area is on a seperate UFH loop, and therefore the room doesn't quite heat up evenly when the UFH kicks in. Once at temperature though, its all fine.

Originally we had thought to go for either electric underfloor across the whole space, or part wet and part electric, but our builder recommended we go for the wet system for better heating, efficiency etc.
He had expected to take up normal screed which would have come up pretty easily. Instead they spent 3-4 days gunning up 20m2 of 100mm concrete slab.