Temp

Think I would put a layer down the cavity and a layer of insulated plasterboard on the inside. The inner layer would need careful cutting at an angle to fit the existing.

I'm a bit late but I found this useful... https://electrical.theiet.org/media/1695/electrical-installations-outdoors-a-supply-to-a-detached-outbuilding.pdf

For info.. All services, including supply and fit that might include materials (eg Bricklayers, electrician, plumbers, plasterers) must be zero rated to you. The only things you can reclaim VAT on are materials you buy personally. If shown on a landscape plan as part of your planning permission you can also include trees.

I don't think that's the correct procedure. Pretty sure it should all be zero rated to you. So no VAT to pay and reclaim. Might help to provide the company with a certificate. A letter giving your details, that of the site and copy of the planning permission. Something like.. I certify that the service you are providing are for a new house at... You can also refer them to VAT708. You should get the quote revised before you accept it to say vat at 0%. Note you can't reclaim VAT on anything paid before you get planning permission. If the CIL is in your area don't do anything on site until you have filed the exemption forms and have confirmation of receipt.

If its a warm roof then the void should not be draughty. However if its a cold roof then it should be! You can't really make decisions until it clear which it is.

Yes it would raise the roof line by about 30mm. As it's a semi I probably wouldnt add counter battens.

We have 12mm Hardibacker board behind stone. No tanking but shower tray not wet room. Been fine. You can fix almost anything to it without needing to find studs.

I think I would drain and refill the system, possibly twice, then run the heating overnight and do one more drain and refill adding Fernox F1 or similar next day. Ideally when you drain it measure the volume by filling and emptying bucket so you can calculate the exact volume of Fernox needed. Overdosing is OK though.

Ask for alternative quotes. Presumably this project doesn't qualify for reduced VAT? Eg it's not been empty for years?

If you are replacing the membrane with vapour permeable one I don't think you need a ventilated air gap but you should still allow the membrane to drape unless external counter battens are used to lift the main tile battens off the membrane. Otherwise I would fit one layer of insulation between the existing rafters and another layer at 90 degrees below them as @Crofter suggested.

We did but I think in theory you can build a house without full plans under a Building Notice - so I'm not sure if they can insist on them? Your permission letter will almost certainly have a condition requiring you build the house to the approved drawings. In the past you had to submit three copies and they stamped one set and sent them back with the letter. You can probably download a set marked approved from the planning portal if you don't have them.

It's very variable depending on the council and water co. Was there a condition in your planning permission saying you must get your surface water plans approved? We had one. Soakaways don't work on our soil type and during the consultation period the water co had said that they "wouldn't want us to make local flooding worse". We ended up proposing a rainwater storage tank with overflow into a pipe running along the edge of the road (piped ditch). This was approved by the planners even though it doesn't actually provide storm water attenuation. These days they might ask for that. I would propose discharging into the existing combined system and see what they say. If they object propose putting surface water into the roadside drain/pipe. If they object to that propose a storm water attenuation tank with discharge into the roadside drain/pipe. If they still object propose rainwater recycling tank. If space is tight I believe storage tanks can be closer to foundations than soakaways.

The formal grant of planning permission includes a copy of the drawings that they approved. They want a copy of both the letter and the drawings. Doesn't need to be the original. We sent photocopies.

Basically it's a tank of hot water that delivers heat to both the heating and the DHW. The room thermostats control a pump that takes heat from the thermal store and send it to the rads/ufh A thermostat on the store controls the boiler telling it when to put heat into the thermal store. So the store acts like a buffer between the boiler and heating/rads/UFH allowing them to run semi independently. Bit like a gearbox in a car which matches the engine with it's limited range of rpm to the load/wheels. The main advantage occurs when you have an oil boiler as they always run the burner flat out, they don't modulate/throttle down when the heating load is light. Instead they cycle the flame fully on and fully off. You can imagine how driving a car with a two position throttle would be less efficient. The thermal store allows the boiler to run flat out for longer but also with longer gaps when the flame is off. Gas boilers benefit less as they can modulate down the flame. Especially models that are fully modulating. Not all can modulate down as far as others The down side of a thermal store is the pumps and heat exchangers needed leak more heat than a regular DHW tank. As you are looking at a gas boiler I'd probably do without a thermal store but choose a fully modulating boiler.

Our down pipes go straight into 110mm pipe bends with rubber adaptors/seals. We have a lot of leaf fall which fills up gutters but it's never been a problem for the drains themselves. If we wanted to rod we would need to remove a seal and probably a section of down pipe. I use a wet vac and some plastic waste pipe to clean the gutters. The trick is to have a short 40mm section that is cut at an angle which goes in the gutter but as soon as possible that opens up to 50mm pipe for the bends and down to the wet vac. Works on our 1.5 storey house. Not tried a two storey.