Conor

I second the cheap cordless drill option. Impact drivers are great, but specifically at driving 1000s of screws at high torque. For 90% of the time a cordless drill will do the job. Something like this would do a decent job. https://www.ebay.co.uk/itm/175919185561?hash=item28f599be99:g:buYAAOSwbPhlEBHY&amdata=enc%3AAQAIAAAA0APVs5PUaB5jFLVF%2Bcu%2F%2BmKkNyaYLBlo6VmgVqCAUbLxmqQtJQZxBnf5Ocpnd4kbpj7xtiuOIOZPNvHKYPFtzv%2B%2F5iSfuEFQggulmax6%2FjNaH%2FIIXOXK3AU1nvgCfLfw14Jh6sluquMhdN%2FnMLDFtC%2FC7bZ6Iwzw2jdQQ6o4N8RUEhxdRw3st2E0fETj0bizL3Y0eqXAGf%2FDfdrWJibxrlwn5sQDNV%2B%2FkCUaS3%2FAEilWlhss%2B0vROzKKIWTOAXaOtmf7KgO0D9PCBkFeVStOr%2Fk%3D|tkp%3ABk9SR7ae9tnlYg But I've no idea what's involved in resorting a boat and if you'll be driving a load of 5/6mm dia screws deep into hardwood... In which case you'd want an impact driver.

Just show 5h3 screed guys where 5hry need to bring the screed up to and they'll take it from there. They'll start setting out and compare the datums across the floor. You'll find each external door threshold will be a bit different. Your tiler can make up for a few mm difference at each door. You could go to 125mm insulation but think it might be a bit tight for screed as leaves no margin of error.

Ha. I'll get back to this. When I'm the computer.

5degress is basically a flat roof. Typically min. 15⁰ for a standard tile, I've seen some low pitch ones down to 10⁰. You'll need some sort of flat roof or zinc panel system.

Anytime, really. 5ho I think it's different in Scotland. When we moved in we didn't have running water in our kitchen, any floor coverings, and only one working bathroom. Bear in mind, work will grind to a crawl when you move in, and you might have vat reclaim issues as seems HMRC have (in the past) used the date of occupation as a definition of complete, and the three month countdown on vat reclaim starts.

Th bit I had to fill in was long and narrow, just ran a couple lengths of rebar along the length. Tbh a few 300mm dowels or threaded rod drilled in to the edges of the slab will be enough.

In that case, shutter from below with ply, dowel in to the slab, and then fill with concrete. I regret not getting my openings done in the factoy, so much harder afterwords!

Did you check that size of opening was OK with the SE/supplier? Have you cut through one or two cables? For mine, once services through, I cut a piece of ply to suit, fixed battens to the sides of the slabs so ply was level with slabs. Bit of foam or cement to seal it off. You'll need to make the rest of the levels up with insualtion and a bit of cement + self leveller.

Unless the floor slab and walls of garage are insulated, no point. If you can foresee a use of the garage in the future that would benefit it being able to be easily heated, and kept warm in the winter, then change the design to incorporate insualtion. Putting a UFH loop in the screed/concrete will cost pennies. If it's filled with inhibited glycol, no harm in it sitting dormant for periods. NB building control implications of you make the garage part of the thermal envelope of the house.

Mortar under the dpc, mortar above the dpc. A 20kg coping stone isn't going anywhere.

You can downsize to 80mm for just the run to the final plenum on each branch. Otherwise best sticking to 125mm for the rest. Also, with 125mm ducting, you don't actually need plenum boxes, just a 90⁰ bend, short length of 125mm duct and put your air valve straight on. Save you a good £20 per room.

Pretty sure the OPs house is finished and lived infor some time. Short of ripping up the floor and spending a fortune, nothing you can do.

Drop a small false ceiling down, maybe 300mm deep, 400mm wide, along the length of the room.

Bed preparation is key. Weeds growing up through the new turf will be your biggest issue. Other than that, it's straightforward, just avoid hot, dry weather (so lay in spring or have sprinklers on the ready, same as sowing from seed really.)

Put everything down on paper, especially if he's assuming H&S roles and responsibilities.

Each LA varies, but generally if it's a new dwelling, the access needs to meet the highways requirements. Regardless if it's the modification of an existing, or a new one.

Tbh, I'd spend the little extra and dig up all the old clay pipes and lay new PVC, outside of the extension area. High chance of old clay pipe failing when building over. Easier to move the lot.

We got the most expensive insinkerator brand one. Deals with bones just fine. Not tried teeth yet.

Get an insinkerator in your final kitchen.

I had to more than double the extract flow rates to balance the supply. Your unit will balance the fan speeds anyway.

Quite often, cutting a hatch through a board is easier than lifting an entire sheet, even if this just screwed down. 10mins with a multi tool and you're in.

Money supermarket. Etc etc. What's your construction method? We're ICF with basement and got insured with LV for something like £350.

I'm almost certain you could build a much more optimised new house for less money than the extensive renovation / modification. I think what is drawn could be in the £1m ballpark, based on £3k/m2 plus risk. A simpler two story new build would cost about the same after VAT allowed for, but with less risk and the final product would be nicer, warmer, more desirable and valued more. Keep doing your homework and report back in a few months

I don't think what your architect has sketched is constructable, not within a sensible budget, at least. I'd be amazed if your existing structure and walls will take that much modification and additional loads. Id expect extensive steel work, underpinning and piling. Take a step back, look at different options. Speak to other people. We were in exactly the same scenario 4 years ago, and bought a property to renovate. Lift roof, additional floor, extension, all that. A quick scrape around the bottom of the house revealed that there was no way the structure could take it. We don't regret building from scratch for one second. You can achieve so, so much more with a clean slate. Making that design pass BC regs, never mind to a future proof spec, will be a real challenge.

Probably less work just to hire a 5hp rotavator, mulch up the existing turf (maybe spray with weedkiller first of you have issues) spread out the new soil and till again, then seed fresh.