Mr Punter

What is the wall construction? If is is cavity, there should be a cavity tray / DPC above the window lintel sloping to the outside leaf with weep holes either end to let water drain out.

Take up the tiles and fit LVT. Much nicer underfoot. Looks fantastic. You can make up any height difference easily.

Could you kiss goodbye to the tiled floor and fit a bespoke shower tray? https://www.versital.co.uk/bathroom-products-2/bespoke-shower-trays/

The quality films like 3M Prestige are very expensive and require specialist fitting and edge sealing. £80 per m2 as a budget cost.

No, it needs to be zero rated. The labour element will be OK for him as he will not need to pay the VAT or charge it. He will be able to reclaim the VAT on the materials. If he does not have the cashflow to do that you could pay for stuff like concrete directly, although if he has accounts with suppliers he should be able to bill you before he pays them.

Yes it is just outside the CA with no TPO. The branches have to come off to enable construction.

Put the dehumidifiers x2 downstairs. They also add some heat. Have trickle vents in the downstairs windows and extracts upstairs. The gap under doors works well to allow easy air flow.

You could breed with @ToughButterCup and your spawn may have 10 digits!

I have recently bought a plot with an overhanging tree from a neighbour. I will just pay to have the overhanging branches cut back to the boundary.

Is the high humidity throughout the building and throughout the day / year? Have you looked at a dehumidifier instead of increasing ventilation?

Could you have an air leakage test done cheaply? You could then work out where most of the uncontrolled leakage is. The extract rates seem rather low. Can you increase them? Maybe double or triple. In the plant room you could just have a light switch or pull cord fan. I doubt if heat recovery will make much difference to your bills. What is you heating fuel?

@Onoff gets the prize for most geographically distant British Mainland cultural insults in a thread page.

curiouser and curiouser...

No just looking at the guidance here where the reason the lower one is not acceptable is stated as it extends more than 6 metres beyond the rear wall. No mention of "wraparound" in the document.

It is different in Scotland where they have proper weather.

The existing slates may be worth a few quid as reclaims.

None of the the guidance makes any mention of "wraparound", so it is not a relevant definition or description. This is a rear extension. If the extension is 6m or less from the rear wall it is OK. He may need to create a slight dog leg on the kitchen side (if the pantry is currently the outside wall an the distance to the proposed new rear wall is >6.0m) but it looks to otherwise comply.

You don't see that down here but we don't get the weather you do. I like local vernacular building methods. He didn't scrimp on the slate and a halves / doubles either.

You normally get the name of the manufacturer printed on the membrane. Has it been replaced? The battens look a bit puny and are not to BS. You are replacing natural slate with interlocking concrete tiles.

Mixed reviews on Trustpilot https://uk.trustpilot.com/review/www.duration.co.uk

Looking much better. Pocket doors are good if you don't need to open or close them often. They are a hassle to fit and operate and they limit what you can do with the walls either side.

Amazing product. They carry such a wide variety of quality products, all currently on special offer. I like some of the photo compositions in their adverts:

Round here closeboard fencing is 3m bays, panel is 2.4m.

I disagree. The proposal more closely resembles that at the bottom of page 19 and would comply as long as it does not project more than 6.0m from the rear wall. Not sure if the pantry wall is currently the outside wall? It is shown as single leaf.

It looks like a rear extension. I understand it can be 6.0m with a prior approval application.