Nickfromwales

Insulation is wise, wherever it goes. If EWI is laborious, adding the 30mm as I suggest is very simple and does not create any more detailing / work internally. Yes, you'll lose a fraction of internal room volume, but I would be confident this would be a cheaper and simpler route.

Just put 30mm of PIR internally on top of the studs, foamed to the factory-fitted PIR to prevent air gaps between the two layers, and use acoustic "sound barrier" plasterboard internally on all the external walls. That will stop the cold bridging from the studs, eg the connection from the outside layer of OSB to the room interior, and take you where you need to be. You'll need to live 2 more lifetimes to reap the benefit of adding EWI to this detail, so time to worry about something else now

Deffo, and will give a more spacious feeling to the room vs the solid panel imho.

IWI ( internal wall insulation ) is a great idea, and a vast improvement on the previous post!! 🙄 @Richvet, any update?

If anhydrite screed has been used, NOTHING will stick to it until the laitance has been mechanically "scrubbed" from the surface. At that point you will see the shiny semi-gloss finish reduced to a surface that looks a little like a pumice stone. That opens 'pores' in the screed which then allow such primers / adhesives / SLC's to be absorbed / key into the surface.........and then you're in business.

Actually, it wouldn't You'd just screw the sister stud to the left or right of each existing one, the same side all the way down the wall, and the OC's will stay the same. As per my earlier post to do just that. This is probably the quickest and more cost effective solution tbh.

To avoid hitting the straps. I always assume it'll be a semi-give-a-feck individual putting these up, so I make an allowance by providing 3rd parties with an 'idiot-proof' solution. For the window reveals you simply install the battens vertically against the straps, eg to the left of the left strap etc, and then just allow the PB to sail over the strap and form the edge. The PB fixed to the window reveal will come out to meet that and a scrim tape and skim ( corner ) bead will finish that off nicely. No need to apply the shaved batten to the strap, as the distance from the vertical batten to the reveal is negligible.

Yup. The solar revolution has begun, sadly. Prices are going up and soon it will get expensive. Problem is, the cheap equipment posse will be matching quotes from the big names and some folk will be sold a dream and get a nightmare.

You cannot do 10mm from the bath feed or you miss the whole point of the 10mm pipe Indeed, do the run to the basins ( hots ) in 10mm ( all of them ) plus the kitchen sink hot too. If you’re worried about flow, hook up a length and test run the kitchen tap before committing. I’d be shocked if you weren’t happy with the 10mm feeds, on the proviso that they all tee off minimum 15mm supply pipe. Done enough of these to speak from experience on live installs, so this is not a fag packet recommendation.

£10k is bloody heavy tbh. 4kWp fully fitted system from my solar guy ( SolarWatt German manufactured ) would be £8.5-9k absolute max if it were a pig of a job. That’s for glass/glass ( Vision 365 ) panels guaranteed for 30 years. Drop £1k to go to the foil backed classic panels with 20 years guarantee. For Chinese names the price should be lower.

https://www.screwfix.com/p/easydrive-bzp-bugle-head-fine-thread-uncollated-drywall-screws-3-5-x-25mm-1000-pack/25899?tc=ET2&ds_kid=92700048793290424&ds_rl=1249413&gclid=CjwKCAjwve2TBhByEiwAaktM1GXOfiYFdSyFp9XFuuRRjsdj-zinQmJEqVH9GYrZ4DeVNjcPCM1cuBoC0eQQAvD_BwE&gclsrc=aw.ds

Service battens affixed to every stud prob easiest. Maybe a sheet of 9mm OSB / ply cut into strips if you don't need to run cables down those walls? That's a proper PITA of a detail which the architect should have designed out IMO. 2x studs could have been sistered together for each rising strap, with the affected stud reduced by 6mm and its sister left flush for boarding. That's OK to do retrospectively tbh, so would be my favoured option here just to bring the wall forward to clear the straps and screws. Maybe consider horizontal 25x50mm battens at 400mm OC? A ball-ache any way you 'cut' it, as the shortest PB screw is 25mm.

Yes but you hadn't reduced the 4:1 figure which I would imagine is optimistic for heating via rads plus UFH, if keeping existing rads. 4 hours on Octopus? What will you do before that kicks in? If the system has already heated up via 'other' the HP will have very little to do, so deffo smaller HP going flat out imo. Noise for the neighbours may be a consideration, if you have any? Can you introduce a sizeable buffer tank? You could use those 4 hours to heat the system plus the volume of water in the buffer, then for the HP to shut off after the 4 hours expires. The heating would then consume the stored energy before needing to draw off oil again. If your home is very well insulated and has such low heat loss characteristics, then it sounds like this would ( could ) be a good option. Any HP will suffer short-cycling if the house performs very well and the heat demand is very low and steady ( eg after it has been initially brought up to 'comfort' temp ).

Do the hot feeds to the wash hand basins in 10mm. I do this on every job where running an HRC to an outlet is on the borderline of being overkill. Plenty of flow rate even with mains which are half of what you have there. Its just one more fitting each end, so an extra £10 per 'leg'. Chicken feed when you pay nearly £3 for a cup of coffee........

Pipeline Centre should carry stock. This is the best option here, but the OP would still have soldered joints to make at each end. @cwr, you could get a 6m length and have a commercial plumber form a mechanical bend at each end if this is really keeping you up at night. You seriously will be fine with a soldered joint. Any good plumber can solder this in their sleep.

Some manufacturers say the first 800mm - 1000mm in copper, in case the boiler overheats and sends super-high temp water out for a few seconds. Plastic pipe and fittings have very low pressure ratings at very high water temps.

Hepworth do a 6m length in a straight run. LINK People have been soldering pipes longer than they have been pushing fittings onto plastic pipes I've been plumbing for nearly 30 years, and I would use copper in this instance over plastic for sure.

So what is your rain screen going to be then?

A very rough check would be to run them at 40oC flow temp from the gas setup. If the house won't get up to temp, you're going to need bigger rads. You may also need larger bore pipework to get a higher volume of the 'cooler' water circulating around the system.

Get a glass of warm milk and have a bedtime read

Hi. Not garbage, but missing some key points to better calculate your comparison A CoP of 4:1 would be achievable if the flow temp to the heating emitters is very low, but with rads in the mix you'll likely be up much higher. When the temp goes up, the CoP goes down, and it goes down again when winter removes a significant amount of heat energy in the air. Lots of things change these numbers, such as the amount of insulation under the UFH, the fabric and ventilation heat loss of the house ( how many kWh of heat are required to be input to keep the house at 21oC when it's bitterly cold outside ) and more. The oil will be a difficult beast to replace, especially in a home which is not efficient and highly insulated / excellent glazing etc, so maybe consider going for a Grant Hybrid ASHP with an integral oil burner for the bitter parts of the year when the HP cannot quite keep up. LINK

Just solder the joint and move on with your life I've done thousands of soldered joints, water / gas etc and it's perfectly fine. You're waaaaayyyyy over-thinking this. Solder it up, pressure test it at mains for 24 hours, and get it in the ground.

Not magic, maths and sense.

Please don't, it's carp compared to Wavin Hepworth ( aka Hep2o ). 15mm for shower feeds, yes.

I’m not saying to over heat it, but without a decent amount of ‘thermal heat capacity’ you cannot store heat energy and slowly release it, as you do with your storage heaters. Getting the whole house and internal ambient materials / surfaces up to the desired temp then becomes an event, rather than a constant. Uneconomical by comparison eg between thin screed over a little bit of insulation vs passive raft.