Mr Punter

You could have a bank of 300mm on the left hand side and I don't think you would need any on the right. Allow 1000mm width for the hedge and plant it 400mm back from the edge of the pavement, then slope the bank at 45 degrees. Grade the rest away from the house. You will want a fall on the patio of 1:50.

If you buy a "no mar" tip for your Paslode 1st fix nailer and make sure you carefully adjust the embedment depth, you should be OK, but hand nailing is safest.

Maybe just the camera angle but it looks like there is a fair amount of space between the house and the heras and the ground looks fairly flat. Could you not grade the garden slightly towards the path, then have a small bank where the hedge is?

A suspended timber ground floor needs decent subfloor ventilation to outside air and you need to make sure the sub floor area is well sealed from the room above. The Celotex suggested is ideal for this, with a generous application of expanding foam in the gaps to help it fit really tight. You could screw or nail some pieces of batten at 600mm ctrs to the joists at the bottom to support the insulation level with the joist tops and it would also help resist twisting. I would go with 22mm Egger Protect T & G boards (if they are reasonably available) glued and screwed. Seal the edges to the walls with mastic. Overlay with VCL (if you really want to) then ply screwed at 200 ctrs then heat mat and tile. Work out the buildup height carefully so you don't have a step into the adjacent areas.

Bloody hell that was quick! I was about to suggest a new concrete floor, but since you have started, just carry on with what @Russell griffiths suggests. Run some DPC behind the wall timbers before you fix them - easiest to staple it to the back to hold it in place.

The Guttercrest stuff seems to work out about £30-£50 per lin m including downpipes, depending on complexity and sizing. I don't imagine the seamless stuff would be cheap as they must need special kit in the lorry - a bit like some of the metal roof stuff. It is probably only used for commercial jobs where they have nice long runs. I wonder how they form outlets, stop ends and corners (where most leaks seems to happen) without seams, or does the "seamless" bit only apply to straight runs?

I would go with Thermalite or Celcon as they are most widely available. Annoying to run short and be hit with a long lead time. Are you building without a cavity?

Celotex withdrew the whole 5000 range of products following Grenfell. A shame as they were better than standard foil backed PIR. You can probably use any PIR in place as the u values are not that different. You could use a thicker board on the inside of the joists to compensate if required.

I can't be much help but to say we had raking wire balustrade on a commercial stair. Must have been 2m centres and it did not flex much even if I climbed on it. You could ask the wire company to do some calcs and worst case you may need a link between a few of the longest ones to limit deflection. The 100mm sphere is supposed to represent a baby's head so you don't need to factor in excessive force.

I understand that if the soil is clay and subject to heave then the void must remain.

If you have a high or variable water table you will need to incorporate some drainage arrangement under the floor. I suggest that the concrete blinding is laid to falls. @nod did this

Have you looked at Foamglas Perinsul or similar around the edges to help with cold bridges? I think they do 140mm wide. Line it up with the bottom of the floor beams and you will still have enough room for a proper 140mm block for the sole plate to sit on (unless the sole plate can sit on the Foamglas). Incorporate some UFH pipework.

The local authority planning pages should let you see what the most recent use was. You can look up the business rates at https://www.tax.service.gov.uk/business-rates-find/search

Warm roof = insulation above structure and no need to ventilate as all structure is warm Cold roof = insulation within structure and underside of roof deck needs ventilation.

I think the holes make them easier to lay and help stop the mortar going everywhere. You can get solid ones but youstill have perps anyway

I don't know if it is different in Scotland but with building control we have the option of either a full plans submission, where sure you would submit plans including the roof covering specification or a building notice which is for smaller works where you know they will comply. In your case I would do full plans and would expect an approval or a conditional approval, where they list stuff that is non-compliant or more detail required. Once you have the plan approval, as long as you do what is on the plans you are fine.

Should be dished out like rum rations before PMQs.

In your case @andyscotland if as long as building control are OK then it is fine. Make sure the fall is adequate and the ventilation requirements are met if it is a cold roof.

With this one the manufacturer used a piece of metal as a downstand at the front of the treads to satisfy the 100mm sphere rule.

We have a gas system boiler and an unvented cylinder. The boiler is on level 4 and the cylinder is on level 1. Bathrooms are on levels 1 and 2. We have the water timed to heat up via the boiler for 1 hour twice a day. Because the plumber did not insulated the primary pipework well, the TV room on level 2, where the pipework runs across the floor, gets uncomfortably hot so we have to open the balcony door. Would I be better off just using the immersion on a timer in summer, and if so should I also look at economy 7?

I know D4 is the new standard for chipboard flooring but I quite like waterproof PVA / wood glue for the joins and D4 for the joists. Sticks well and less messy and it doesn't form a ridge or push the boards apart.. @willbish if you taped over the joints with a waterproof tape I think you could get the best part of a year out of Egger Protect.

I have looked at Basement Expert and Phil Sacre. He worked on a Grand Designs scheme in London where there was not a proper site investigation or temporary works design and consequently it was a disaster. https://www.homesandproperty.co.uk/home-garden/interiors/design-news/grand-designs-couples-dream-of-escaping-rent-trap-by-building-londons-smallest-twobedroom-house-a114956.html about 10 mins in. I think he has posted on here before.

If this had been counter battened it would have reduced the kick at the bottom. Unless they have used extra long nails it may be that those on the lower course of full slates will not have enough embedment. Also the membrane looks like it will not direct water off as it goes level / up at the end.

Good recommend as it is often the case that windows are let down by install. Ideally best to have someone do the whole job so you are not left with issues. Often I have used approved installers who are really slapdash. They send semi skilled teams who just want to screw the windows in the holes and on to the next job.

@Vijay and @willbish Leave out at least one external door threshold so you can sweep out the water after it rains. I have some big squeegees from a janitorial supplies for just that purpose. The Egger Protect lasts several months in my experience.