Nestor

We have a metal seamed roof so on +25c days we overheat in the summer months in the 1st floor bedrooms, I think mainly because we have zero shade and the building gets 16 hours of direct sun during the peak summer months. I plumbed for AC. We have T&G fibre board over both roof and walls, would not build any other way now. I put the VCL inbound between the insulation and OSB, lot of attention to detail and plenty. of airtight tape.

Similar warm roof build up to mine, though have an additional 120mm insulation and 11mm OSB( for racking) instead of your 30mm PIR. I would avoid Multifoil, I saw some after installation in a new property and it had sagged and no mass. I also would not use PIR between the rafters, never seen a decent fit. Steico, though costly are great products.

We were in for 3 years before private BC got pushy. Just go for it. Have a read :

+1 for airtight tape. Worth spending some time and money on covering all holes. https://passivehousesystems.co.uk/shop/airtight-tape/gerband-586/ No comment on "a contractor".

From memory I probably allowed 25mm on each side as I then fitted Pavatex 20mm reveal board around all openings for windows.

@Bramco That is a fab project and build, the flush roof lights very smart. All our triple glazed Velux are on the 1st floor, bedrooms, bathrooms and landing with fitted internal blinds, just about accessible if you are 5'9" +. Would consider solar glass or external blinds and in hindsight have the large fixed window at the gable end opening. 2 in each bedroom to provide some cross ventilation but will be connecting (plumbed in during build) AC to provide proper cooling.

I used EDW for fitting 7 Velux in Tata Standing seam roof. All I can add is take your time with the detail and an extra pair of strong arms for the lift. Have a look at this for starters.

I agree @Roger440. Its a grift, the ultimate pathological altruism.

Have had a quick look and the dpm is mostly cut short next to bottom of sole plate. I would just try and protect soleplate from water splashes, also fitted rodent stainless steel mesh behind cladding. I wrapped the breather membrane underneath the 40mm pavatherm, green. I extended the Cedar 50mm below batten to protect the sole plate. Once board, 2 x batten and cladding fitted probably 75mm proud of render face. Dodgy drawing enclosed. I would not create a pocket where damp could remain in B.

Enclosed a drawing of sole plate detail on my build, not a builder but I brought the 40mm pavatherm flush with the sole plate and lapped the dpc under. Then batten, counter batten and Cedar. I would not leave it exposed. Would bring the medite board level with block and sole plate. Others will have ideas.

With a tray 1200mm is fine as @Kelvin.

Are you using a tray or flush wet room floor? We have overhead rain showers with a wet room walk in shower tray kit, 900mm x 1800mm. Fitted a 1400mm x 1950mm shower screen secured with a horizontal bar at the open end. It works fine and not obtrusive. Anything shorter and water would exit past the screen. I would consider losing the 800mm screen and fitting a 1400mm only. Easy access. Fit 50mm waste if not too late.

I use flexible tile adhesive usually on 6mm or 12mm cement board base. Your existing floor and joists need to be solid.

Quick scan at your drawings. Not dissimilar to our build, as @ProDave make sure you have a ridge beam, try and get 1.5m before roof pitch starts. Make sure Velux are accessible by hand or automate and consider external blinds if possible. Make sure the other bedroom window can open, do not rely on Velux for cross ventilation. I would rotate the kitchen island 90' anti clockwise and change hob to sink. Consider how to address overheating and cooling issues now. Lose the chimney / fireplace for a stove / flue. Spend on airtightness. This bedroom photo is 6.2 metres wide with some built in draws / cupboards. 1.5m to the eaves.

Same spec as your Lindab, 125mm Half round Majestic, 87mm downpipes. Cannot fault it, excellent quality, design and fitting. Just the cost, I have 78 metres of guttering. Your fascia detail looks fine to me in the drawing, all my feather edge on 25mm batten. I had to make a combined fascia / soffit board out of Douglas fir due to the overhang.

@Stones Maybe it does have a fault or I misunderstand the indoor & outdoor temperature settings. I think I should set the indoor temp as low as possible, 16c and the outdoor as high, 20c to enable bypass. The Outdoor Temp screen enables you to choose the minimum outdoor temperature at which the bypass will operate in degrees Centigrade – only displayed when the bypass is fitted.

So 5 years in and think I now understand the summer bypass has minimal effective function in the warmer months. It's 16c outside, it's midnight but the air supplied is at 23c with summer bypass on or off. I naively assumed with the bypass on it would supply the external temperature and have a moderate cooling effect. Is the heat exchanger supplied by the extracts? Help.

I made and fitted the fascia boards first before fixing the horizontal Douglas fir cladding. Does that help?

@AdamSee Yes, lots of hanging around by the fingertips.

My son made some sort of hangboard? above the door, he removed architrave then used long wafer screws to fix through to stud work. Not moving. Then left home.

@Tom Home made cut stringer yet to be finished, temporary hand rail etc....yours looks fine.

Have a look here. https://www.fhbrundle.co.uk

Marshalls Driveline Priora https://www.bradfords.co.uk/product-mar426-driveline-priorar-permeable-paving-200-x-100-x-60mm-charcoal-8-08m2?gad_source=1&gad_campaignid=21419188078&gbraid=0AAAAAC3XVZy1CYchyxu_zsJB-bDxfT6NZ&gclid=EAIaIQobChMI3PD41r2mjgMVAIFQBh0wMiUCEAQYAyABEgJ7U_D_BwE

I had a problem with being recommended and purchased a Vent Axia based only on area and not volume. All based on 2.4m ceiling heights. Due to exceptional ceiling heights in 50% of our dwelling the MVHR could not reach the minimum requirements for building control even at 100% boost. I had to be a little creative with figures for BC to pass. However our MVHR runs 24/7 at 30% and seems adequate for our needs. The Zehender 600 has an air volume of up to 600m3/h at 200Pa.

@flanagaj Like you we are south facing and have no shading so do overheat. I plumbed for AC in the first floor bedrooms and the main family room as seemed simplest to install. We have PV so running cost is offset and have ASHP for DHW and heating. We cross ventilate in the evening to purge the house as @Russdl. Would consider built in external blinds ( no view, natural light during the day) and solar glass next time.