Temp

Our architect produced a great design but way over the original budget. To minimise cost keep it simple.. Avoid roof complications like dormer window or 1.5 storey houses with rooms in the roof. Stick to a 2 storey house with simple roof. Even making the house L shape adds a bit although how much is debatable. Do you really need a chimney? A working chimney? Avoid anything needing steel beams or posts if possible. (eg windows that wrap around the corner of a house). Architects tend to like charging a fixed % of the final build cost. Sometimes as much as 10%. So if you splurge on a kitchen just remember to add 10% for your architect who may not have had anything to do with the kitchen. Better still find a builder you trust so you dont need an architect involved during construction other than perhaps a few hours to sort out design problems that might come up.

We have a B&B first floor with UFH. Think the make up is... 75mm UFH in screed 80mm PIR (would use more now) B&B Floor 150mm beams with 100mm blocks (so 50mm void between beams) Battens on clips supplied by B&B company Plasterboard. The combined depth of plasterboard, batten and 50mm void was just enough for Fire and Part E rated downlights. Our SE recommended using two steel beams in our largest room to reduce the span that the concrete beams needed to cope with. Thses steels are deeper than 150mm so the tops project into the 80mm PIR. I can make a sketch if thats not clear.

And as someone pointed out to me once.. if they decide he is making his living from building houses they will charge income tax not cgt on the profits.. https://thepropertygroupsite.com/2019/10/03/capital-gains-warning-for-self-builders/

Can HMRC decide he is really a "Mainstream Contractor" under the Construction Industry Scheme (CIS).. https://www.self-build.co.uk/make-money-self-build/ https://www.dobanti.com/articles/can-you-make-money-by-self-building/ He should read the rest of those links as well.

There is some spin going on. Some reports suggest the govrnment will allow new gas boilers to be installed if they are "hydrogen ready". https://www.hvnplus.co.uk/news/uk-boiler-industry-provisionally-backs-mandating-hydrogen-ready-systems-01-03-2021/ I recall reading somewhere this might add £200 to the cost of a new boiler?

Google suggests... https://www.hygienesuppliesdirect.com/pearl-super-concentrated-horse-tail-and-mares-tail-weed-killer

@Nickfromwales will the mixer work if he does that? Or should the mixer also be moved?

I'd go with @PeterW suggestion. Perhaps under/overlapping the lead more like 150mm.

We had an issue with mares tail in Belgium but ony in one flower bed. From what I can find on the web Mares Tail is able to grow through hardcore, tarmac and weed control membranes... https://forum.gardenersworld.com/discussion/983962/mares-tail-what-to-do https://forum.gardenersworld.com/discussion/999541/best-weed-membrane-for-horsetail https://forums.moneysavingexpert.com/discussion/6026745/tarmac-driveway-some-advice-please I think if they did a half decent job first time around they are being generous with options 2 and 3. I'm thinking that tarmac might not be best choice. At least with gravel the weeds don't break it up. This youtube vid has interesting recommendation for killing it but we ended up moving so I havent tried it..

For the WC... My recommendation is to go with something more or less standard size and shape so replacement seats are easy. Avoid a very short projection pan unless you are sure the loo seat will stay up. There are also a few pans around with non-standard hole spacing (eg distance between flush pipe, bolts and waste pipe). I'm also not a fan of WC that only allow the seat to be fixed from above. Invariably I've found the expanding plug like device rotates allowing the seat to move. Much less likely on those that have "nut" on the underside.

+1 to filling the holes with a polyester car body filler (sets quick so work fast). Sand smoth and use ct1.

PS: Instead of asking for quotes for the whole job you might also consider hiring a "man and excavator", buy your own pipe and sand.

No issues and it will still help maintain pressure. Yes to sand, no need for conduit. Use narrow bucket on digger to save on sand. Yes. See below. You also need marker tapes.

Looks like the developer may have sold them some sort of land, design and build deal.

https://www.thesun.co.uk/money/15014020/luxury-mansions-devastated-homeowners/ Says one owner paid £1,057,000 for his plot in 2016. "He told the inquiry he had launched litigation against the developer but "they had disappeared" and refused to take responsibility for "what they have done"."

+1 They certainly look very out of place. Problem is the developer managed to sell the houses.

Think this may have come up before but can't find old thread.. https://uk.news.yahoo.com/planning-bosses-order-mansions-demolished-dispute-100526374.html "Owners had appealed against an order to demolish the houses but their claims were rejected and a planning inspector has now given them 12 months to demolish the structures and return the site to its previous state."

Some companies use a slotted insulation to hold the pipe in place. Definitly not needed in your case.

https://www.greengatemetals.co.uk/scrapmetal/prices Could be £4-£6 per kg.

I think properly ventilating the 50mm void will help in summer. I'm surprised how cool my outbuilding is and I think its down to the well ventilated void behind the timber cladding. Its frequently cooler in there than in some bedrooms in our roof that have far more insulation. So I would look at decent sized eaves and ridge vents to get convection going.

See Diagram 19 in Approved Document J. https://www.gov.uk/government/publications/combustion-appliances-and-fuel-storage-systems-approved-document-j That appears to require a separation distance of 1.5 pipe diameters between the flue pipe and combustible materials and a non combustible shield and air gap. Think this rules out using EPS or PIR in your case so will need to look at non-combustible insulation like Rockwool behind a fire proof board of some sort.

Is that temperature gauge reading 50? Can you take a pic of the whole manifold.

One zone downstairs is probably fine if they are all living rooms. I would put each bedroom and bathroom on its own zone so it can be turned on/off/up/down at different times. We find it nice to crank up the bathroom temperature in winter but leave bedrooms at 18. You can get stats with remote sensors for bathrooms. Now our kids are away at university the UFH in their rooms are off and their doors shut.

+1 Best get input from an SE before doing any modifications.

I've had a look at the pictures and it looks like many other badly built houses. I agree with all the things @markc mentioned. The way the outbuilding has been built close to the house was probably acceptable to Building Control when originally built., however.. The pitch (steepness) of the roof looks quite shallow? Possibly too shallow for the tiles used? If so that could allow rain to be blown under the tiles. Any chance of a picture from further back so we can see the slope? I also suspect the flashing over the gap has failed or was badly installed allowing water into the void between the two buildings. The flashing should be wide enough to cover the first ridge of the tiles. This is a slightly different type of flashing but see the left hand side of this image.. Sorry if the council man laughed, I'm afraid they probably see far worse although that's no excuse.