Iceverge

Any drawings of your roof and wall interface? If it's complex then I would recommend moving your airtight layer outboard of the rafters.

Seal any air paths too with acoustic caulk.

No calling me by my real name. This is supposed to be an anonymous forum.

I'm thinking idiot resistant ( not idiot proof, that's impossible). Simple pattern to lay. Single zone. Run at a low flow temp. Would it actually make any difference to the feel of the house avoiding walls beds, kitchen cabinets etc etc.

Ok..... Having a brainwave here .......it's hurting......there's blood coming out my ears.............. Take a well insulated house with an ASHP. Lay UFH at 200mm centres Don't bother with room by room patterns. Just slap it down in a big up and down pattern or whatever. Pour 150mm of concrete over the top and then ensure no one drills more than 75mm into the concrete. And after than go to town with room layout etc. "Trim" heat the bathrooms with direct electric to make warmer if needed. Any reason this wouldn't work?

Yup, I had 26mm mlcp coming from the UVC inexplicably via a manifold to the kitchen tap. It took about a minute and 9-10 litres of water to get warm at the tap. Solved (9-10secs) and about 1l of water to do the same thing with 10mm Hep2O. I should really have put the UVC closer to the kitchen.

According to the makers. MCLP is suitable for hot ring mains where Hep isn't. It has more in common with hydraulics fittings than plumbing. Its rated for 10Bar continuous at 70deg where Hep you'd have to drop to 50deg ish to get the same rating. It's pretty achedemic in a domestic install but for a commercial setting I can see the advantage. In Ireland and UK we can't seem to get the 12mm fittings. I really like the 10mm Hep. Its like installing 3 core cable rather than pipe and for a radial system delivers hot water extremely fast, coupled with the slim inserts I'm getting 6l/min over 16m at 3Bar. That's plenty for everything except a shower/bath or jetwash kitchen tap. Failure mode in my wellwater experience is metal corrosion (copper/brass) and I love that Hep can avoid this almost entirely. I expect the stuff I put in to do 75 years +.

It's been the standard go-to in Ireland with a while for new builds I've seen. You can buy screw fittings if you don't have the compression tool. It's a very robust system. HEP2O is an easier system to install in my experience and has less restrictive fittings for flow and plenty good enough for houses. I would be happy with a multilayer system if done well though. Much more so than copper or cheaper push fit.

Don't forget physics. Meaningful energy transfer will only occur when there's enough temperature difference. A slab at 24⁰ will impart very little heat into a room at 22⁰ but a lot into a room at 15⁰. Given identical pipe spacing, on a single zone, the room with big windows or a leaky external door will extract far more energy from the UFH all by itself than the small internal room. Its not the case that a pantry will end up at 30⁰ and the hallway at 15⁰. The pantry will probably get to 22⁰ and the hallway to 20.5⁰. In a passive class house it'll all end up at 21⁰. Regardless of pipe spacing or omitting rooms or forgetting UFH and ASHP and just plugging in a cheap oil filled rad.

If you are certainly pursuing IWI . Like John says above. Wrap everything in 25mm of PIR. foam the cracks and joints. Trim and tape. It'll be adequate for your needs.

Lol, that will amusingly make the heat route downwards through the steel so it may not help retain that much heat. To be effective you will need to wrap the entire steel and wall ( inc between the joists ) in Insulation. A small bit everywhere is more useful than a lot in one place.

I've "thermally modeled" the junction....... In short the solid wall above will do such a good conducting job from inside to outside that no further heat will pass through the steel ( it's not actually creating any cold bridge) and it'll remain at indoor temperature. Unless you plan EWI or IWI ing the solid brick wall I wouldn't give it any more thought. Similar story with the posts. A thermal bridge only becomes significant when it is disproportionately worse than the surrounding materials. The posts to the ground might be in an issue if piercing an insulated raft in a passivhaus. In your case it won't make any real difference as the existing walls are uninsulated anyway.

I suspect your humiliation is extra high in the bathroom. Is the extractor fan working?

Very strange indeed but it's not entirely impossible there's a bad batch of seals or heat exchanger a floating around. It would be easy enough to set up a rig to pressurise one side of the unit and see if it leaks out. I'm thinking a couple of bungs, a Schrader valve and a bicycle pump. Pressurise the exhaust(or inlet) side and see if it leaks out immediately. Perhaps something as simple as a dab of sealant would be enough to cure it.

Self building is a bit like golf in that rather futile pursuit of perfection I suppose. Mind you I don't play golf.

It was my parents house. They have well water which EATS copper for breakfast. Of course I could have put in a water treatment unit etc etc bla bla but I risk/wallet assesed that a Hep2O olive and insert into a brass fixing (as per their manual!) was a satisfactory solution. I was able to run the pipe joint free to its final destination too which pleased me. In any case its accessible from the rear through a cupboard and any leaks will end up in the shower so I think I'm covered. None the less my advice is to listen to the Welshman, especially if you are on mains water.

What access to machinery do you have at the moment? Is there layer of topsoil existing in the area you plan to raise? Will you DIY this or get a landscaper/builder?

Sentimental attachment? If not I'd recommend knock and rebuild. Any pics? The construction type will change the advice.

https://www.plasterers1stopshop.co.uk/product/plasterboard-pvc-edge-bead-12-5mm-x-2-5m/?srsltid=AfmBOorQvJbCIIUOacdScHTyybmkxk6-Reoj9fvgTCU_mV-xb9e_OQqU Buy a length of the above. Dry fit it first. Just to the right of your pencil line, "holy" side nearer the glass. Get some double sided tape and stick it in place exactly. Where you want it. Use some thin self tapping screws to screw the bead onto the frame. In the valley of the bead so to speak. Dry fit some plasterboard for your reveal. Squirt some FM330 foam (NOT TOO MUCH!) on the reveal, enough to ensure a full fill of all voids and a continuous seal all around the window. Not too much that it will expand and crack the plasterboard. Anywhere you fear a leak onto the frame you should mask it off first. Slide the plasterboard into the bead and then screw onto the reveal. You will be left with. 1. A board mechanicaly secured at both ends. 2. A thorough insuation job. 3. Arrow straight reveals following the line of the bead. 4. A good key to stop skim chipping off the board near the window frame. 5. Good air sealing at the reveal to window junction with the FM330. P.S I wouldn't be tempted to use a metal bead. The frame will be colder than the rest of the room and a metal bead will attract condensation and rust over time.

Worry is what gets me, worry and eating a meal too late. ( Supper ideally on a plate no later than 5hrs before sleep, snack later if needed) Self build is often battling to get something to a standard above the humdrum, hence conflict and hence, for me, worry. I would prefer to do it myself and take years and avoid the worry or ideally only work with reliable high standards people. Both are impractical in reality. To curb the worry I have tried to give up the things that trigger me negatively emotionally. The news was the top of the list. I still consume a lot of current affairs podcasts but limit them to ones that tackle the subject dispassionately. The FT does some good ones. Instagram got the chop, Snapchat, Facebook. Not deleted the app but eradicated my accounts. All in all you're not alone. I went to the beach with the family today. It cheered us all up after a very wet January here.

I did.........it's working still ....2 years later...... Or just listen to Nick.

Single A2A and direct 300l UVC here and pull cord heaters in the bathrooms. Pros. Very simple to control. Daikin app for a2A and time clock for UVC. Spacing heat is cheap. Cheap to install. Heating the UVC to 70/75 on immersion allows it all to be done on TOU tarriff. Simple to repair. Cons. A2A sounds like a fan. I can't fix or install the A2A, needs an f-gas man.. DHW uses 10kWh/day. Vulnerable to elec tarriffs. It works just fine, add a few PV panels and I reckon it's the cheapest thing you could have over a lifetime. Next time I think a monoblock A2W, cheaply bought. A 300l UVC. Simple UFH. Under tile electric mats in the bathrooms. It'd be as cheap to run but be more luxurious than the blown air option I have. Allow a 70mm blanked duct through the wall and a fuses spur for an A2A for cooling if ever needed. Ps. I'll take suggestions of "simple" UFH. Could a single 100m loop be enough. I don't know enough about these things

That's fair.

Go the whole hog in that case. Take the insulation and airtightness line outside the attic space and a regulation staircase to access. Design dependant though it can be much much dearer. In our case making the footprint bigger or a garden shed was multiples of times cheaper. Suitcases in the garden shed or be sensible and just take hand luggage. MVHR should be inside the heated envelope, I've seen issues with vibration and noise when in the attic. Care is needed. Also you need to get at them to replace bearings and filters. House battery should be away from the house entirely in my view given the severity of Li cell thermal runaway. Kids toys should be sold on eBay unless they're being used. I'd have loved a trainset as a lad but couldn't get any cheap as they were all hoarded in some geezers attic......

I was dead set against it from an air tightness and hoarding point of view. I have never seen anything in an attic that didn't belong in a skip. I even found a timber box of gelignite explosive in my parents one from the 1950's. It's a place where people who can't organize their brains stick their crap. Rant over, I did include one, only for access to inspect. I might visit once a year to check the roof and to say hello to my insulation. Airtight(ish) + insulated(ish) attic hatch and 500mm OSB upstand to keep the cellulose in situ. I added 500mm of a PIR "plug" that fits into the OSB upstand box to keep in the heat. I reckon it comes with a U value of 0.05W/m²K. No storage allowed thank you very much.