Dave Jones

lol 5kwh to boil a kettle. math is not strong here.

https://www.buildtestsolutions.com/air-leakage-testing/leak-checker-diagnostics-fan

The issue you will have is how will you turn the equity in your current house into cash ? Maybe extend mortgage ? Self build normally works by you buying the plot outright and then haviing a deposit to the build in cash. Selling up and finding a cheap renter (put furniture into storage) would be my preferred option over a caravan and all the issues that come with it.

totally agree. old buildings can be destroyed by adopting modern insulation and building methods. Im same going above the standards where its financially feasable. I think the most payback will be in targetting passiv levels of air tightness. I'm considering buying the 'lite' version of the blower door tester which gives the ACH so can do it at first fix stage where its still possible to sort them out.

its not clear cut for a refurb. If you look at Part L regs the target is 0.18 for a floor BUT the threshold limit is 0.70 if achieving the target U value is not technically feasible or would not achieve a payback of 15 years or less.

hard to run the tv off the hot water tank though lol Battery is a given to do the solar job properly.

If the work is done to the quote what's it matter if Fred or George is the one doing the work. Looks like your looking for a reason to penny pinch. Remember if you ever want to get him back in the future for snagging penny pinching now will burn that bridge.

2 x 2 is plenty. id use a top plate to catch a few joists/noggins and frame off that like an upside down lantern upstand.

make sure you have the plastic insert inside the MDPE pipe before tighting.

digdat will give you a map of mains .

thats is a tad expensive. Jockland prices I guess.

would have thought a 9 inch grinder and new diamond blade would make short work if it. You can buy a bull nose wheel for the grinder as well to soften and smooth the edges after. The lads who did our hearth had one made a lovely job of it.

we paid £1200 for the core drill and test, they went down 5M. Took around 3 hours.

what sort of price for a standard 2mish window ? to give an idea ?

i see you had to narrow the risers to comply with building regs, shame as it makes them look more cluttered. Had open backed in our first home back in the early 80's, carpeted all the way round each riser is a lovely flower pattern not far off the colour of your purple walls. Does help with the 'boxing in' look especially when you have multiple flights .

clamp timber to it to use as a guide for the blade, cut slow and plenty of water.

100 gives you more options though.

problem is they do not have a fixed input cost. Timber prices over doubled last 2 years. So if you paid your deposit when and then it went up by 30% prior to delivery they are fecked. They can rob peter to pay Paul but eventually the wheels come off. They wont have the capital to forward buy a years worth of timber and if they did who would offer such terms. It's not a viable build option by any stretch of the imagination and its a shame self builders are fooled into thinking paying double because it goes up quick while the rest of the build sits for 18 months anyway is a good idea.

quantum theory.

risk all that effort by not hiring a couple hundred quid pump for a couple hours. baffling.

If they dont like escrow then a solicitors undertaking could also work. It puts their solictor on the hook for the cash if it goes pete tong. If they refuse both run for the hills they are using your money for cash flow.

stick to 100mm centres if you want to go for low flow temp for maximum efficiency. Dont/limit zoneing. Get it airtight and size doesnt really matter.

what m2 is extension ? block and beam may be faster.

you have a cold roof by the looks so as long as your ventilation space is open both ends for air flow then you can mix and match insulation as it will be able to dry out.

if your air tight wont need it. Surprised your passiv designer even specified it which is worrying.