Conor

If it's a rubber O-ring seal, then you only hand tight. Over tightening will distort the seal and result it in leaking. You might have damaged it so might just want to replace the whole unit itself. Duct tape in the meantime.

We hired a telehandler for a day to lift ours in to place. You have to allow for the length of the lifting straps and reach over the scaffolding (you'll want your scaffolding up to first lift before your first pour) a 7m one will do the job for first floor level, you'd want a 14m for roof steels, as an example.

Millions of people drink water through lead pipes. It's chemically managed in the system and the risks are very low. Especially as you'll only have a short length of pipe. A 3-6month wait for a utility to do something is, unfortunately, fairly typical. Keep hounding them, and drink the water in the mean time.

There's a better, safer way of doing this. Walls are cast, beam set in place, chemical resin anchors used to fix the beam in vertically to the concrete. Horizontal lengths of rebar welded on the flanges and to the starter bars in the concrete. Next concrete pour covers the lot. That's how all of ours were done.

How much? Something like 200mm won't be noticed. We switched from cut timber roof to insulated panels, resulting in a 300mm increase. We dropped the ridge by 150mm and wall plate by 50mm.

I mean the cooling water. You're going to have to use 1000s of litres a day to get any effective cooling. Does it recirculate to a ground heat exchange? Does it go down the drain? If it's just your daily home use, it may not be enough to make much of a difference.

Where does the water go? How do you manage condensation? Is it ventilated? Is the room fully insulated? (We wanted a cooled pantry room and even with an underground basement, looked into AC, ground cooled air etc, proved way too much hassle and expensive and we just have a second fridge)

Nope. We've three stacks, all AAVs. No issues. Satisfies BC.

Ours are 3g, can still hear even light rain. Less than 2G, but still loud. I don't mind it. White noise. Grew up with it.

Out heatpump and cylinder, buffer pumps, glycol, gubbins etc was £6200. Plumbers were about £1200 (6 man-days) but that included UFH commissioning and a few other jobs. Spark another £300. All inc VAT.

Air admittance valve rather than going through the roof.

You own from the downstream connection on meter box onwards. The leak is 99% sure to be at the connection/ coupler on the backside of the box, as from that point should be a continuous length to you kitchen stopcock, and should be a single length of MDPE. I'd phone water co and say you think there is a leak at their meter box. Depending on how it was installed, the meter box may have come with a 1-2m tail, then your pipe would have connected with a coupler. Or, your pipe could have gone straight in to the box. Either way, the connection point is the water cos problem. I've seen LOTs of twisted / bent pipes coming out of boxes that continuously leak.

the water in the trap is enough to stop the "sucking".

Don't do it. 20mm insualtion is nothing, you'll be chucking away loads of heat and it'll cost you a fortune to run. Either rads or dig up your existing floor and lay an insulated slab.

Replace the valve then disable your legionaries cycle.

Ask the SE if the beam can be moved in so it sits over the inner leaf, and the plate extension out to take the outer leaf. This will greatly reduce the crossectional area that's bridging. The plate will likely need to be thicker.

Where does the steel sit relative to the cavity? It looks like it's in the inner leaf? If it was within the cavity or external leaf, then it needs to be a galvanised post, which it isn't. Is there a drawing showing the bifold detail? You want to avoid cold bridging here.

I bought a fancy detector thing. Strong magnet is used far more often as faster and more accurate.

You ideally want to run 110mm PVC pipes under the slab, then up where the drains will connect. You don't want (can't?) to run 50mm standard PVC pipes underground. I recall your other post about the shallow 110mm pipe. This will be the same situation.

use a proper rest bend with foot and a SINGLE length of pipe going to the outside and set both ends in a little concrete. Then pack in around with insulation and foam. Put the pipe in before the insulation. BTW, 150mm EPS doesn't seem like very much to me. What grade is it? In an insulated raft you'd normally have 200-300mm

No, you get telescopic platforms that have a good 10m horizontal reach.

Have all deliveries offload at the roadside, arrange a telehandler etc in advance if needed. Most of ours except concrete and screed and smaller lorries were left at the roadside. We had a lorry rip off our postbox, and another coping stones along our neighbours wall. They don't give a sh1t.

In winter, during a prolonged cold snap, it's not unreasonable to assume you could be consuming 20kWh a day. And your PV could only be generating 1 or 2kWh. 2kWh (based on my 5kW producing as low as 200Wh on a dark day in November and December.) You'll need an alternative power source. Re the mortgage issue. You'll potentially run across this every time you remortgage, and will not get the best rates. Also, what if you want / need to sell in the future? How many people are prepared to pay full market rate for an off-grid house? Finally, you'll be way, way, way over producing in the summer with all that electric going to waste. If it were me, I'd still go for a decent array, but get the grid connection as well. I hope you can get the price down.

Just the same as house conveyancing, we paid around £1200, but then a few extras (indemnity policy, extra searches) brought it closer to £2k

Almost certain you would for cladding and balcony. And quite possible uPVC cladding will be rejected. A lot depends on local context.