Iceverge

Welcome @Gary Martin. Always nice to hear of new ideas. I tried plenty on our build. Almost every time I had pushback. It falls into two camps. The first being a genuine logical, regulatory or cost reason. Second being people don't want to expend the energy to think about it. I'll try to avoid the first camp!

I was in a new house today with UFH in a slab above 200mm insulation. The house was a pleasant temp but underfoot the floor felt exactly the same as our house with 200mm insulation and no UFH. Not warm, not cold. UFH with hot floors are generally a symptom of a badly set up system or a high heat loss house. The exception to this is electric UFH for bathrooms which is generally only for short bursts anyway just to heat your toes.

It can be done with OSB in lieu of screed. Compact the stone base well and get it dead level. It may need to be laid in several layers to achieve this. Install a layer of EPS. Install your DPM. Another layer of EPS with all joints crossed. Install 18mm OSB with a suitable expansion gaps. Glue and screw another layer of 18mm OSB on top. With all joints well staggered. Tape the edges of the OSB to the walls to prevent any air or water leaks into the floor.

It sounds like a thermal bridge which will redirect any condensation driven decay to the bottom of the studs. What is the issue with timber sole plates?

A vote from a ramp here. You can continue to enjoy your garden indefinitely then.

True but it reminds me of this.

For what specific reason are you hoping to use UFH?

12mm seems very thin for engineered flooring. I suspect it's 12mm laminate you mean? In that case you could just swap it out for 6mm LVT which I would prefer anyway.

It'll work, but it will cost an absolute fortune to run. You'll have 6 times the advised heat loss through the floor. Be cautious of reviews, especially ones online. Lots of them are just bought from click farms. 2 sensible options. 1. Dig out the floor and do it properly. 2. Stick with rads and use warmer floor coverings for your feet.

https://oldholloway.wordpress.com/2016/09/ Another way to use straw as a building material although it really is a timber house with straw insulation. One of my favourite houses though but I think I would stick build it instead and blow in cellulose. Not without it's risks though. Cost, long supply chains, and the issue of the walls starting to grow if they get wet in the building process.

@Selina Here's is what I would consider to be a higher quality straw bale house although in reality it is a timber house with bale insulation. https://passivehouseplus.ie/magazine/new-build/norfolk-straw-bale-cottage-aims-for-passive However it relies solely on external render for rain protection. I wouldn't consider that wise in Islay which has about twice the rainfall of Norfolk and much of it horizontal.

Reminds me of my cousin who is a geologist and has a very different take on climate change to most people. He can't believe how short term our perspective is, but then he largely deals in Eras.

Agreed. As a structural material or an insulant bales bring lots of issues. Nothing is Impossible, but to get a high performance straw house will be much more expensive than alternative methods. Especially on an island with very high winds, rainfall levels and straw bales that will need to be sourced hundreds of miles away. As an insulation material alone I actually like straw. It can be installed as a blown product in a similar fashion to cellulose. At a guess it has less environmental issues as the access to second hand newspapers for cellulose to recycle is diminished and more virgin paper is pulled into manufacturing. https://www.iso-stroh.ch/en/ I don't know if anyone doing it in the UK or Ireland though.

I would argue the toss on this. I would say there's nothing too modern about blown cellulose, EPS or mineral wool. I'd take them any day of the week over PIR, Phenolic or Aerogel insulants.

Looks fine. Mineral wool and then stick on the soffits.

Could be worth staying stum. Maybe the seller thinks the saw is no good and want rid at a bargain price.

As usual with sound you have 4 issues. 1. Airpathways. The big issue here is the doors. They're very lightly to be the weak point. Really focus on getting an absolutely seal all around them. (This may require dedicated ventilation to the music room) Similarly seal the ceiling plasterboard and the stud partition plasterboard with acoustic sealant in a hermitic fashion. 2. Decoupling. Mainly an issue with the stud walls and ceiling. A dropped metal ceiling or resilient bars will do here. 3. Reverberation. "The drum effect". Anything that you hit a thump of your fist that noticeably acts in this manner needs a layer of fluffy stuff inside to prevent it. Similarly dissuading harmonic frequencies is important. Use differing thickness of plasterboard on both sides of a wall for example. Add some foam to the back of the fire doors to stop sound bouncing around in the void there. As it's a dedicated music room you could consider lining the walls and ceiling with acoustic foam too. 4. ADD MASS. Not required for the 225mm wall or the poured concete wall. There's literally tonnes there already. Remember all that you are doing is buying kilogrammes, not magic beans. Dense rockwool, MLV and other secret sauces are expensive ways to buy these kgs. Standard plasterboard, soundbloc and OSB and are all the cheapest at about 60p per kg from memory. More is better, including on the doors.

What a great observation. I'm going to have to concoct some project that requires gabions now....

Scrim tape over it. Stick a couple of long screws through the tape into the beam to give it some structure. Skim over the top as best you can and leave it dry. Skim it smooth then. It'll be as robust as any other part of the ceiling.

I stayed over at a mates house recently that was about the same vintage as yours. I could not believe just how cold the tiled floors were. They were very uncomfortable under socked feet. Hurt your bones cold. Pain through your knees cold. I totally get your desire for UFH. Meanwhile his living room which was wood/laminate was quite ok to walk on despite being, on paper, of a very similar U value. As said above, the heating losses will be very large unless you dig out the floor and install a chunk of insulation so in order to increase comfort at a fraction of the cost I would consider installing "warm" floor coverings instead. Laminate, LVT, vinyl, carpet, cork, wood are all good options IMO.

Short answer 120m².

Ok, I see what you are saying. The priority risk is wind driven rain making it's way in between the eps foundation and the woodfiber ultimately damage the sole plate and sheathing so I would be keen to keep a mechanically robust detail in place here to stop that happening. However I would argue that if your window and door detailing is done to a good standard above this, then you lose the benefits of a completely taped wind tight layer unless you secure the membrane to the foundation.

If you tape it it should be fine. However the effort in doing so might not be rewarded in any extra resilience over just cutting it off. As a general principal I would very much lean towards a simpler build is better. Extra membranes and tapes goes against this philosophy.

No mains sewerage here so on a domestic treatment tank. Our AAV is working perfectly so far. We have a vent stack that runs up the back of the garage.

Absolutely. A cardboard model. The a ply model. Then a bird house. Then a dog house. Then a pump house. Then a garage. Then the house.