torre

+1 to using pedestals, we'll probably finish our exposed patio edges with vertical tiles that fix to the pedestal with clips example, which hopefully avoids the risk of vermine getting below

Fair enough on the neighbourly point then, sorry. Moving or losing 400mm may still be simplest though.

As @Conor says, moving it just 400mm will be simpler and maybe a bit more neighbourly too? It's going to be a substantial not very attractive building that it sounds like you might cut corners on and you don't want close to your own house - they probably don't either!

We're only just into G99 but my impression from our installer was that the DNO set an export limit rather than just saying no.

Pop up plug with wireless charging maybe? I'm not personally a fan of pop up plugs, but neither do I like expensive phones easily sliding / being knocked off hard surfaces in a working space. I do like @Conor's charging drawer idea!

One thing to check is whether they are SBD or PAS24 approved, required for a new build. I'm sure the Rationel will be but the Cortizo may not be - the 4600 isn't their most common model. We bumped into a situation where they have a PAS24 certified configuration of their Cor Vision, but not their Cor Vision Plus. BCO wouldn't allow the Plus. Cortizo is rebranded a lot so might be a bit less consistent. If you can, it's nice to be hands on with these big sliders to get a feel for their quality

I thought 25mm was the minimum for roofing anyway, wouldn't use less

Tektite push fit copper might be a decent alternative - slimmer than plastic push-fit externally and wider internally, no need to hire / buy tools versus press fit (which Tektite sprint looks similar to assembled) Working on our own house they're my preferred option if I do need joints in copper but generally I prefer long runs in Hep2o terminating to copper only as needed.

Bit surprised with the focus on fire safety you'd get any concession on this one. Maybe they thought you'd slim down sweating while waiting to escape? 50mm is more than a fraction, I think you might struggle to get that past a BCO. There's no point being able to climb halfway out of a window but jammed on the cill. Maybe if it's picked up on (or you're on the larger side anyway) you can look at whether it's easy to make the stairs a protected corridor instead?

For a door handle, plug, switch etc I'd think in terms of swapping one out from the least used room rather than preemptively buy spares. Kitchen door/drawer is probably the one that worries me a bit and if I was having a custom colour or finish would worry more. Expensive to buy just for spares though. It's always reassuring to have a couple of full tiles or flooring planks left over, but generally from a planned %wastage rather than buying a whole extra pack for spares

Plastic lift and slide like Aluplast will probably be able to handle that size / height and have decent u-values but may not be any cheaper than the popular aluminium systems and will definitely have bigger profiles.

Regs are pretty strict about tundish discharge. You definitely can't run in hep2o or similar and I think your tank size limits whether you can discharge into soil stack. We ended up with 35mm copper for a similar length run as you have to size up depending on length and the number of bends

In real life don't put your toilet that close to the wall, next time you're sat on your throne enjoying a quiet moment of reflection pay attention to how much space you actually need at the side.

On the inner leaf of the new wall - if you want something to show your builder then LABC publish renovation guidance that covers this including a diagram on page 14...

Personally I'd worry at least as much about leaks around the rest of the home. Drain with a waterless trap sounds good here but there are smart leak detectors and remote shut off valves that are probably a better fit in most cases

Honestly that will be the least of your issues compared to the effort of cutting rigid insulation to retrofit tightly between old joists. Much easier to do something such as @JohnMo's suggestion. Pretty sure this will fall under building control renovation of a thermal element.

Congratulations on a lovely build, I'm jealous of how well you've kept to schedule! I think this is a really good way to reflect on costs - you've achieved a better house, got exactly what you want, all without paying over the odds - plus you're lucky enough to have enjoyed the self build experience along the way.

Most people chipping in would lean towards more space kitchen side based on lived experience and so maybe future buyers will think the same, but at the end of the day, you're much better placed than us to know how you'll use the space and you've clearly designed for the limited space with your lift up cupboard doors and lots of drawers, so (as exhaustingly ever with our own projects) you have to trust your own decision making. One possible approach would've been to tile through, not fix down the island and see how you live with it but I think that ship's sailed. Very nice kitchen by the way!

Having seen the photos, I'd personally want to compromise on the dining side to give more space kitchen side now I see it's the main working space. A better trade off might be table width 800, or you can probably reduce walkway to 1000, probably reduce the chair space to 200 when pushed in, consider banquette dining seating to save around 150 - basically pick options and get to say 1050 for kitchen (our last house, wouldn't have wanted less - you'll wait or push past not walk around the island in real life), assuming it didn't impact the living space far end too much

@Super_Paulie yes that's great for working space - looks like your pinch point of island and worktop corners is an example of what I mean? Quite a bit narrower but only used for passing through.

If it's a secondary walkway with an occasionally used cupboard and having an island versus say peninsula is important to you then down to about 800 is workable I'd say, as long as there's better access around the rest.

The fixed scope and the background of that scope being defined in the context of costly issues with your previous roof may well weigh in your favour in any action, but there'll still be risk in any court action. Have you checked whether you have legal cover in your home insurance or self build insurance? If so, they may offer advice.

Yes raise the issue, 22mm is a lot to be out by DPC. What were the foundations like? Has he created a problem or inherited one (even so he should've been picking this up)? If you'll have level thresholds at multiple openings over that length then one potential problem might be you'd struggle later with a liquid screed. Our brickie had to pick one corner up over a few courses, marking the spacings for the next few courses out on the corner profiles seemed to work well (say the good end is 75/150/225/300 then the low end mark 77/154/231/308 etc) until you're back level. You have to have an honest discussion, ask how he plans to get back to level, suggest taking down a course or two as the lower you start to fix this, the easier it'll be. Give him a chance and then decide from his response (both attitude and actions) if he's someone you can work with or will be battling with for the rest of the brickwork. When you say soil pipe into the back inlet, I guess you only mean grey water, not a toilet?

I'd be getting in touch with your tilers before doing any remedial work. If you're having problems already it's hard to believe they won't get worse, put the onus on them to fix any issues

Have you considered swapping the toilet and sink positions? Shorter soil run, keeps toilet tucked away, better access to stuff on shelves when at the sink. Maybe run 32mm basin waste into the 50mm shower waste for one less connection at the stack. Personally I'd lean towards a rectangular shower following the room shape.