JohnMo

Looking at one of your previous threads it says you looking to build 100 to 120m2. If that's still the case your heating demand for the whole house could be as low as 1 to 1.5kW. You should get good built in airtightness from the Sip if your still going that route. Which Scottish building regs will drive you to MVHR. What is really important is getting the boiler sizing right, in nearly all cases they will be hugely oversized. So plan from the offset for a big buffer. If you are doing UFH you should make sure you can flow at low temperatures - 25 degC or so. Don't zone your heating use thermostat as limit stops not temperature controllers. Otherwise you will get short cycling of the boiler and big lpg costs.

Your size is ok if electrical stuff behind plasterboard, if there is plumbing 50mm makes life easier. On a ceiling if you are doing down-lights 50mm means the led driver will fit in the cavity.

Things I made sure of before I started the build. Takes from the below are 1. plan on paper, 2. Alway go for the simplest way - keep it simple. Don't build technology into a building that may not be supported in a year's time. 3. do not change design unless there is a really good reason. Your mental attitude needs to be looking forward, how do I get from A to B and C and so on, once A is done it's done move on. Don't ask for too many opinions, as you will get 101 opposing views, that all valid in their own way. The order I did things Made sure layouts where right, we went to the beach and draw out the house in the sand to make it flowed right, scrubbed bits out, added bits, did this a couple of times. Sorted where we wanted light switches etc. Did as much upfront as possible to limit any decision making or more importantly changes during the build, tried to keep things as simple as possible, no clever or complex stuff built in to the fabric of the building. No paid for learning curves at my expense. Still a 1001 things you are asked during the build, but that's the nature of building a one off. Discussed with contractor how they were going to do the build process. Realised pretty soon, they didn't want us on site during the build and we would be invited a key stages only. So knocked that idea on it his head and went self managed, mostly self build. Changed build method to ICF, so it was easier for me to do the walls. Had plans redrawn and new Warrant (Scotland). This caused a 2 month delay. Explored myself internally what I could and couldn't do on the build, and what would be given to others to do. In the end we had we had the following changes to initial design, after building work started CAT5 cables installed in all rooms - an add on to electrical scope. Made sense while electrical work was being done. Changed from main water to private borehole, due to the stupid high price Scottish water wanted. Posi joist roof rafters instead of cut roof. Joiner suggestions to save time on site. Worked really well. Changed the roof insulation to spray foam. 2 day job instead lots of days. This made sense with the posi rafters as all gaps are filled. Reduced the size of a hall cupboard, to make hall feel more generous. That was one my scopes of work, so saved time and materials. Upgraded windows from double to triple glazed. Expensive upgrade.

Why buy a house when you don't know what you plan to do with it. Are you putting the cart before the horse?

Just look for an Ames taper. I paid around 3.5k for labour only, I supplied all materials. But on 192m2 bungalow, main living room vaulted 6.5m high, all other rooms had an angled ceiling approx 3 to 3.5m in most rooms down to 2.5m for some of the smaller rooms. So not the easiest job.

Our original plans were cut joists, but the joiner recommended posi-joists/rafters. Came cut to the correct length and shaped ends, no trimming on site. Longest rafter circa 9m, all manual handled in to place. I then added counter battons to give 350mm cavity. Mine was spray foamed; as I couldn't find a cellulose installer anywhere close to me.

That would one huge battery.

Front door for each bedroom, what wrong with that

I would get the land lord to fix it. The install instructions state. Check the flue draught which should read 10—20 pa, or 0.1 to 0.2 mbar. if you have a suitable flue draft, you should not get smoke in the room.

Are you using the connection to outside air?

Would you then include for a fair comparison, the enclosure ie the house shell and the insulation, the finished linings etc. - then you are back to why are heat pumps so expensive?

And back to the question - why do cost so much?

It is the same. A fridge removes heat from the air (inside a fridge) and moves the heat the to room. A heat pump removes heat from the air in its location and puts into the room.

We had intumescent paint on internal doors, it looked cr*p. Got building control out the way, rubbed it down lightly to knock of the high spots and acrylic painted over the top, looked the same as the other doors without the intumescent paint.

I would download the install instructions and see what the manufacturer says, with reference mounting and none combustible materials. Then go from there.

If your electrician doesn't know what he recommends, maybe you should be looking for a more experienced electrician.

Similar to above. Plant room, isn't right. Access to be bedroom via a plant room? Quite long duct runs from MVHR due to its location. You are doing double stud walls internally (waste of time in my opinion) but the noise will pass through the door undercut 10mm min. Not sure about the two access doors to the downstairs toilet. I would ditch the door between the bottom of the stairs and toilet. You don't seem to have a utility room? Storage space is limited, where's the hoover going and other stuff you want out of the way? Upstairs is a mess, just not right. Our house is about the same size, but with 3 bedrooms, all rooms are good size without being small or huge.

Why? Sounds like over kill. Main living space and main bedroom have a multifunctional sensor. £150 to £200 each. They can be stand alone items, we have mains wired CO2, temperature in lounge and bedroom. What benefit is there wiring it all into a central brain, bit lost with that one. MVHR, leave it as stand alone item, manual boost switch at each wet room, possibly auto humidity boost. Job done. Look at filters every sex months replace if required. A big house tends to be very over ventilated rather than under. MVHR, comparison

Just been looking at some other prices and some are plain daft. AV installation £70 to 80k Over £60k for electrical install incl lights MVHR, not sure how you design to building regs and passivhaus standards as they ask for different flow rates. Seems to kicking in around £100k for plumbing and heating. Item 067b, would advise not to full fill partition walls with insulation, as it needs an air gap to perform best, 50mm would be a better choice. Been looking but cannot find ground floor installation?

One tray per panel, is the norm. Internal blind - normal roller blind for example, fits inside window reveal. Old school. Or just close the curtains.

It's not rocket science, you are trying to overthink it. Was in the local b&q the other day their price are the same as Wickes and they had loads of stock. Just roll it out it will find its own level, plumping is great for a day or two, it will then find its own level with the help gravity.

Background, I have a gas boiler. But the assertion that heat pump don't work and he wouldn't sell to his worst enemy, is more a statement of his skill set, or lack of. A correctly designed, installed and commissioned heat pump will work and shouldn't cost any more to run than a gas boiler. The key is correctly designed, installed and commissioning. Solar PV and thermal, can work great in the shoulder months, but they cannot deliver a heating system. Example I live in NE Scotland and have 3.1kW of PV. The other day it was generating 3.01 kW at around midday, today it was generating 0.1kW at the same time, as it was very heavy cloud and pouring with rain. Generation is winter is about a 10th of that. IR rads work great in a single direction, so they warm your body that is exposed to the heater. If your back is away from the heater they will remain cold. They are 100% efficient, but that's not good compared to a well installed heat pump which could be 400% in the same weather. If I had a shed used as an office for a hour or so a day, IR would be fine. LPG, not convinced with your argument.

You really should be aiming at a really tight fit. Any gaps that remain spray foam then tape. Remember to add the perimeter boards before the fill insulation, the use a thin DPM membrane on top of the insulation. This serves two jobs, it's good to prevent screed getting below the insulation, if it does the insulation will just float. It also stops a chemical reaction between the aluminium coating on the board and the concrete within the screed.

Do you need to go through the could at all, with a Willis heater, could direct heat the water? I believe that was the original design intent. Ask it then heats top down, so you can a part hot tank or a fully hot one.

Your solicitor should be requesting all this info from the seller. The full warrant package should be available to you that includes the layout prior to modification and after. If the seller has lost them they are available from the council for a price, that the seller should provide to you the buyer free of charge. It's their obligation. Builder go bust all the time, sometimes on purpose.