Conor

Hi, yes, we used landscape. From ITS technologies. They were really good. I just sent them the schematic of the layout and they built up the order list.

We've 50mm liquid screed on top of 200mm insulation across 115m². The diminishing returns for floor insulation seems to kick in at ~200mm (PIR) or more, going by people's experiences here. 50mm screed will not crack, unless you drop an anvil or something! I do admit, there there is a subtle bounce / resonance about it, you can tell it's not "solid".

You don't need anything on cemfloor. Just stay off it until it cures properly. Our plant room and large storage room in basement are both bare cemfloor and there is no noticeable dust or wear.

Well done on the work so far, and welcome. You're saying all the right things and I think your approach is spot on. Why timber windows? Double the price of aluclad PVC for no real benefits. What is your floor construction? Any scope to insulate?

If you are tight for room, prioritise the supply side rather than the extract. I only had room for one and put it on the supply side, all silent. I used the 150mm cylindrical ones from Lindab. They are huge.

Suggest 150mm floor insulation with 50mm liquid screed rather than 100mm insulation and 100mm dry screed. You want as much insulation as possible (to a point)

Yeah, take it all out, full fill beads instead. At the builders cost. Will have a lower u value in paper but will perform better. I'd also be looking at insulated plasterboard.

I'm assuming that the brickwork in this pic is the external skin and the blocks are the inside? If so then you've a 10mm+ gap between the insulation and internal skin... Cold air will circulate through this, negating a large portion of the insulation. I.e. it'll be cold. It's needs to be rectified.

You really want a gully trap. The amount of crap that comes off a roof is impressive. We've two at the front of the house that connect to 110mm pipes that just open in to the gravel backfill around the house. Having the gully and the grid means none of the leaves and sycamore seeds can get in and clog up the outlet.

All you really need to do is cut out the screed just around the pipe, cut the pipe down to just below the floor level, stick on a 45⁰ bend, 70mm or pipe, another bend, and that should get you clear of the dishwasher. It's an hour's work. The dishwasher will be sitting on your tiled floor, so will be about 20mm higher than it is.

Spend a bit of effort on making it less big and drafty. with an indicated heatloss 10x bigger than what we're used to seeing here, I don't think the normal assumptions apply here. I've looked up the datasheet for your heatpump. The first thing that jumps out at min is the min flow rate of 1lp/s. I don't see you you can achieve this through UFH loops in a normal domestic setting. You'd be needing around 10km of loops across 40+ individual loops. Is this what you have?

Get digging, I'm afraid. We had the same issue with a electrical conduit. At least you spotted this before flooring! Another reason to install kitchen before flooring.

Interlocking rubber mats on top of whatever you have. We used it to make a temporary play area on our deck while building our house. And remember, they'll soon grow out of out.

You want 150mm minimum, 100mm and 50mm layers.

Nice blossom tree in the middle, gravel the rest with some spot planting. I don't understand small lawns. Pain in the hole. If you do want a lawn, for whatever reason, you have to dig out about 200mm of "soil" and replace with good quality topsoil. I could think of better uses for ~£3k.