Mr Punter

You are best off contacting the designer / developer.

Good to hear @Mrsmedhurst. Did you do this?

What you have shown there is an 1800mm high single skin wall. It would be useful to have some drawings to work to and have a structural engineer do some plans, calcs and spec. You will need all this for a building regulations submission.

You will be able to get enough fall from the bottle gullies without any more fittings.

The consumer unit sounds fair. I think you would be OK doing the strips yourself if they wire the switch(es) and the drivers. He is probably charging a fair amount because he doesn't want to subsidise the use of a filthy sex pond hot tub.

If that is the price they quoted and you agreed to it I can't see how you have lost out. Did you get any other quotes? Best to get 3 if the job is worth more than £2k.

It is worth filling in the little bits at the top and bottom to keep the insulation fitted without gaps. You can always stuff in some mineral wool if the PIR is too fiddly.

This only applies to flats and attached dwellings. Not needed for detached. Has he been in the job for long?

Why? I have found that cooking creates a fair amount of heat and odours and a ducted extractor see to them both very well. We have one with the fan mounted externally and rigged up with 6" ducting so it is both quiet and powerful. Filtering the smells to recirculate is not efficient and means the motor has to work even harder.

Can you have interlocking tiles, or are natural slates a must have? The imitation interlocking ones will be a lot cheaper and lighter and I doubt most people would ever notice.

Change the fan to something that has proper backdraught prevention. I quite like the Icon ones but there are lots about. Beware of the external flap vents that make a horrible rattle when it is windy.

Yes, it was news to me too. Chunky looking though and clearly designed to work with the shear forces.

Never used the screws before but assuming the fit OK through the holes in the hangers they look good. Also, if you mis-nail a hanger they are tricky to move and the screws could help. I am a bit crap with a hammer and the twist nails just seem designed so I keep smacking my fingers. The screws would also be good for the concealed type hangers. Do you need the 4mm ones for a standard hanger? 5mm seems quite fat.

https://www.google.com/search?sa=N&biw=1920&bih=966&source=univ&tbm=isch&q=oak+wood+floor+reducing+strip

I would not bother with safety. If you include handrail it will need to be fully safety compliant. Planning would not want it used as a roof terrace / observation deck. The roof needs a fall of min 1:60 preferable 1:40 which is normally achieved with timber firrings. You can have it so it falls in 4 directions like the pitched roof. This will be good for the skylight as it will let it drain.

There is no bestest. Some of the felt products are very good nowadays and lots of roofing contractors are familiar with them.

If these are sliding patio doors, can you just have a 50mm wide transition piece from the (say) 18mm wood floor down to the 10mm threshold? You may find the flooring supplier will do one or know someone who can machine it.

The final utility connection is normally done by the monopoly company for water, gas, electric and phone. You can do the sewer yourself / your contractor. Electric you run duct from the road to the inlet point, water run MDPE pipe from the boundary to your stopcock. Gas like you to leave them an open trench. They seem to really like turning up when the scaffold is down and everything else is done, then getting you to dig out a trench.

If you lay them offset you will need shedloads of feet. Even if you just have them stack bond you will need a foot for each block plus a load for the perimeter. I think you have already sussed that you will need to cut them as they will clash.

Those blocks are designed to go on a solid bed like sand, mortar or concrete. If you want to use the stilts you can use decking or pavers. I have them with non-slip porcelain slabs on a roof terrace. Maybe just store the blocks somewhere next to the walk-on glass...

Once you start to sink the ground floor you almost need to treat it like a basement for waterproofing purposes. Can you sink the surrounding ground?

The ACO will help a bit. You could bring the cement board down a bit. You are trying to have the external ground at the same level as your internal floor and it won't work out. The DPM under the Celotex is almost trying to do the job of below ground tanking.

Did you consider using a Marmox or Foamglas Perinsul course under the timber frame to stop cold bridging? Also, there should be 150mm min to the DPC.

Controversial I know but I have used holesaws and gone in dry. I just make sure that it is kept cool. I sometimes use a step drill bit for making holes larger but I have only used this on thinner material.

You need to get yourself into as comfortable position as you can and be patient. There is a sweet spot where it will cut through nicely. Don't rule out using a core bit and just make a larger hole.