Temp

I believe the one on top helps stop water loss from the screed making it weaker. Something like that.

Might be worth checking out any implication for the CIL. For example a self builder can only claim the exemption before work starts on site. I'm not sure if demolition is considered starting. It's possible that demolition might save them stamp duty but hit them with the CIL. There should be a common sense solution but the CIL rules don't cover a lot of common situations.

Think I'd cut blocks of PIR and use expanding foam to fill behind/around them.

This. If within 2m the whole building must be under 2.5m https://ecab.planningportal.co.uk/uploads/miniguides/outbuildings/Outbuildings.pdf

+1 I think it should be mandatory to fit cavity closures when windows are replaced if they aren't already present. Go at it with a can of expanding foam but be careful as it's easy to over fill and push off external trim. Do a test first as it can carry on expanding for a fair while.

Found this although I'm not sure the way they calculate averages is correct. Should be weighted by the number of houses in each age band? It's also worrying that for detached houses it seems to have gone up after 2006? https://tools.bregroup.com/heatpumpefficiency/dwelling-heat-loss

Historically electricity has cost roughly three times gas on a per kWH basis. So it's important for most people that the average COP is more than three or running costs will go up. Can that be achieved with 60-65C flow rates? The other problem is the size of the heat pump required. According to this web page... https://www.boilergrants.org.uk/news/how-much-gas-does-a-boiler-use The average gas boiler in the UK is rated at 35kW. It's claimed that lower output ASHP can be used by running them for a higher percentage of the time. But the same argument can be applied to gas boilers. I wonder if we really have enough data about the "load factor" of gas boilers in cold weather?

I did ours back in 2007 and found this guide useful.. https://electrical.theiet.org/media/1695/electrical-installations-outdoors-a-supply-to-a-detached-outbuilding.pdf Hopefully not out of date.

Is the top shaped to form a cavity tray?

Just make sure to fit pipe inserts.

We replaced a big flourescent with the 120cm version of one of these in our utility room. Plenty bright enough for us. https://www.amazon.co.uk/gp/product/B07WMMLJFZ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

If the buyer doesn't like that reply you could consider applying for a Certificate of lawfulness on the grounds its too late to initiate enforcement action. Might take some time though.

When we're they added or we're they original to the house? If added later the porch and garage might not even have needed planning permission. Might be permitted development... https://www.planningportal.co.uk/permission/common-projects/porches/planning-permission https://www.planningportal.co.uk/permission/common-projects/outbuildings/planning-permission If they did need planning permission and it wasn't obtained the time limit for enforcement action is normally 4 years (unless its a breach of a planning condition or a change of "use class", in which case its 10 years). Back in 2006 my council allowed access to the paper planning files. Don't know if they still do. Last I heard you had to ring up and make an appointment the see files for an address or specific planning ref number. If you don't get anywhere I would see if your solicitor will let you reply with something like.. "The porch and garage we're constructed before we purchased the property 8 years ago. The planning status is unknown. It is possible they were constructed under Permitted Development Rights but the buyer should satisfy themselves that this is the case. If planning permission was required and not obtained it is possible that it is too late for enforcement action to be initiated, but again the buyer should satisfy themselves that this is the case."

Ok then I think I would either put a hot manifold in the kitchen or if no room just run pipes with isolation valves. I've only shown one hot pipe to the living room /aquarium end but perhaps you need two.

MOT can vary a lot depending on what its made from. Our builder liked to use one based on crushed limestone. That sets like concrete if its got a lot of fines in it, but the surface can become pretty slippery when wet.

Might be hard to underpin from the inside though 🙂

No I was thinking more like this but perhaps the run to the kitchen tap is too long..

At the very least you want two courses of engineering bricks with a DPC between the slab and frame. I would do something like this.. or this might be better still. Use a 4" frame and line whole thing with insulated plasterboard. Might also want a vapour barrier behind plasterboard. Could also tank the outside face of the brick and concrete with a paint on tanking compound. Do think about the door seal. Is there any risk of standing water forming in the area? Pipe in the gravel for french drain?

Not sure what thickness would be needed but at 0.2m... 500 x 3 x 0.2 = 300 m^3 That's about 600 tonnes. 20 tonne loads on ebay are around £600. 600 * 600/20 = £18,000 Some haggling will be needed. MOT type 3 is water permeable but I don't know it compacts as hard as MOT type 1.

Farmers often just lay a lot of hardcore or road planings on farm tracks but I think they need to register an exemption.. https://www.nfuonline.com/assets/6453 Not sure if this applies to you. Is the drive a shared farm track or just part of your residential property like most driveways?

Perhaps run cold main up to the boiler and the hot and cold from there to the upstairs bathroom and from there down to the understairs bunker.

This. The spur can be wired into the back of the socket giving both sockets free.

It can be worth connecting your MVHR into an energy monitor plug. As the filter blocks up the current consumption increases, or at least it does on mine. Our filters are quite a coarse foam similar to that used to filter aquariums. I can wash them out with a garden hose or in a bucket of hot water.

If I've understood what you want I would replace the boundary wall at the courtyard with a new wall inline with their parapet wall. Yes I know it means sacrificing 2" or so but sometimes going for the neat and tidy option is best. Especially where waterproofing is involved. This approach would mean all the rafters would be same length an angle. No joggle/step in the gutter. Then I would copy their roof but mirrored over and longer to fill in the courtyard area. Their lead work looks a bit untidy at the ends (?) but the joints on the parapet wall looks neatly done to my eye. Lead flashing and secret gutters are tricky to get right and some builders just can't seem to do it. I would suggest getting a detail drawing done for this area, possibly by a dedicated lead worker? Make sure the builder follows his drawing and has him come back to do the lead work.

The wiring centre controls the manifold pump. The wiring centre also controls the ashp unless you also have a thermal store.