Conor

You just need WiFi. We've NO signal in our basement, very intermittent on the ground floor. No issues with WiFi calling enabled.

Magnet is great method. Put a bit of card between the magnet and the wall so you don't mark it. Use it all the time in our ICF house as there is no other way to find the plastic webs

Open cut and reinstatement will be the fastest and cheapest option. Ask around for a contractor that can do this. Biggest hurdle will be road opening license and utility searches / tracing / trial holes etc. the work itself is less than a day for a small crew. I've a mate that does this sort of work, based in Dundrum and works all over Co. Down, Armagh and Antrim. He's usually super busy and hard to get hold of tho! Esp now as he'll be maxed out doing pothole work.

Just use standard PVC pipe and surround in concrete. There should be a detail in the BC regs for this. What fall do you have with that cover? If it all goes wrong in the future, then you can look at a new connection. Definitely worth the gamble.

Unrelated, but one of my worst mountain bike crashes was due to a pothole. Towards the end of the Mega Avalanche qualifying, cruising down a short section of connecting road, had one hand off the bar to give it a rest from the brake pump. Hit a hidden pothole, next thing I knew I was about 20m further down staring up at the trees. Knocked myself out, broke my helmet and cam, slightly concussed and had whiplash for three months. Worst part was I was running well in the top 25, maybe 10, and was only 5mins from the end of the run. bike was fine tho 🤣

Is the track higher than the floor level? If so then just pour the SLC upto the current floor level and work gently with a flat trowel. Just make sure the channel is cleared of dust, dampen a bit with a sprayer or wet sponge. No need to prime. Tape over the track to protect it

Self levelling compound.

Anything you put there will be full of roots in a few years anyway. On the plus side, with the hawthorn the ground will be quite dry. Id just backfill with 12mm clean stone.

Need to see the whole floor layout and the ground floor for context. And don't be afraid of moving stairs, not as difficult or as expensive as you might imagine. In your first drawing you're losing a lot of valuable space to corridor.

You're not a proper DIYer until you've put a foot through a ceiling.

Increase the floor build up by 50mm to 200mm - 150mm insulation, 50mm liquid screed. Then either live with 50mm lower ground floor ceilings, or raise everything up by 50mm, which nobody will ever notice.

We had that. Renders put another skim in the affected areas, not noticeable since.

Why do you want to clear it? Let it go wild and maybe stick a few down native trees in and let nature enjoy the space.

I looked at this. Yes, you save the equivalent of a couple courses of bricks. So what? The cost came out the same, was no faster, was a niche skill that needed additional design and prep. You'll want a suspended ceiling for minimising sound transfer anyway.

Just use a layer of 50mm PIR on the bottom, with 100mm on the top. Your local merchant will have 1000s of these in stock, at good prices, as that's what the building trade uses. They won't have any /much 75mm PIR or EPS. As a consequence , 50+100mm will work out better value than 2x 75mm. Thin EPS is a nightmare to work with as it just snaps. Foil faced PIR holds together better, can be cut more precisely, despite it being "harder" to cut than EPS. You also can't have steps in your inusaltion, so just allow the screed to take care of those level variations. (Our floor is 50mm eps, 50mm PIR, 100mm PIR, 50mm screed. 50mm eps at bottom as we changed from 100mm to 50mm screed last minute)

That's a lot of glass for one room, esp with the roof light. you meeting regs with that?

NIE won't allow any of the suggestions above. At a push, they will allow a cavity meter box installed into a wall attached to the house, but within 2m of your consumer unit. We were in similar situation with our ICF build. Architect suggested either fitting in the return wall, or by building a false wall type protrusion against the house and flashing it into the main wall. First option was a no as we didn't have the return wall built, and the second option would potentially cause issues. In the end, as I added 100mm additional insulation, we had the depth to cut out insulation and fit a standard cavity box against the concrete core. A minor cold bridge in the grand scheme of things. For you, I'd suggest the return cavity wall, if it fits in with your landscaping plans.

Looks like water is running down the pipe from above. Likely an ill-fitting tap letting water down from splashes in the sink area.

We had to build over a shared pipe at our last place. It was original 1950s clay... we added an inspection chamber upstream of the foundation, and replaced the 8m or so of clay pipe with PVC. Its not difficult or expensive. A diversion may be more problematic if you have to introduce bends and changes in fall.

Where did you get the tiles from? We had similar format tiles years ago, cheap from B&Q. Tiler immediately showed us how uneven and warped they were and that he wouldn't be able to do a perfect job. But this looks more than irregular tiles

We had a similar issue with a door frame. We didn't want the faff of removal and waiting months for a replacement, so we compromised and they sent somebody out to spray paint the inside. Flawless and you woulnt know the difference unless you got down and had a really close look. Start thinking along those lines and what compromise you might be willing to meet. As above, all comes down to the spec / order sheet you signed. our window were very thorough and clear in this regard. Had a simple one pager with the big items like quantity, colours, spec, and then a full booklet with the extreme details of every individual unit.

A better way to do it is to aim for a total heat demand / load per m² and make sure your build hits that through design choices and build quality. E.g. PH standard of 10W m² and take if from there. Decide what you want from your house, how you want it to feel and perform, and design accordingly.

What's in the cavities? Have you checked? And as Redbeard says, you want 400mm in the loft. It's by far the easiest and most cost effective way to improve insulation in the house. A few have mentioned drafts, but if you have condensation issues, im not sure that's a big issue.

Make sure the foul is the lower of the two pipes. Check the building regs, for pipes that shallow you might have to cover in concrete. Paving might not meet the needs.

This will be one for insurance to sort out. Definitely don't start ripping stuff out. Make the notifications, kick up a fuss, but don't put your hand in your pocket.