DaveH

Should I just fit an air admittance valve into the pipework inside the island unit or am I better running a separate vent pipe back under the insulation too? I'm guessing an air admittance valve will be fine but I don't want to find out after I've laid the UFH and screed that something else needs to be in there! One last question (I hope).

OK. So the 50mm to 110mm reducer would go onto the back of the gully and then it would connect into the Y branch and feed into the drain? Ability for rodding is always a plus!

Thanks Peter. Obviously there will be a bottle or P trap under the sink but you mean underground too? If I put a Y branch into the foul drain, then a P trap, and finally a reducer will that be OK to drop the 50mm pipe into underground?

Thanks. My slab is already in without pipes or ducting. Is the attached diagram OK? sink drainage.pdf

Trying to get my head around exactly how I should run the plumbing for a sink and dishwasher to an island before I lay the insulation, UFH and screed on the concrete slab. I will run hot and cold feeds in plastic pipe inside separate ducting along with an electrical feed for sockets. Can anyone advise on the drainage side of things please? There will be a run of approx 2.2m to an external wall and I'm thinking the best route would be straight through this wall to the side of the house as the main drain runs here, although not at great depth at this point (under a footpath). The main soil stack will be upstream from where the sink drain will emerge. What is the minimum height above the main drain that this sink drain should be? Also, I'm guessing I'll need to factor in a vent pipe or air admittance valve somewhere? Inside the island unit or run an additional pipe back to the wall (to be hidden behind wall mounted units)? Thanks in advance

Thanks to everyone for the input

So far one vote for each method ? I guess there isn't particularly a correct and incorrect way to do it - just positives and negatives to weigh up. Studs first, I would have concerns about cold bridging and I would want to protect the bottom of the studs from the screed. Studs after, obviously you need to know where the UFH pipes are, although just gluing the sole plate down eliminates risk of puncture. I would however need to locate the UFH manifolds and take account of some first fix plumbing and wiring so at least one wall would have to go up prior to the screed. Finished floor surface will be a combination of tile and timber.

Apologies if this has been covered many times. I have a slab lower ground floor and block and beam upper ground floor. I have found conflicting advice on whether to install studwork first and then lay insulation, UFH and screed, or insulate first, lay pipes, take lots of photos and measurements, screed and then fit studwork. What is generally considered the best approach? I can see positives and negatives to both ideas. Thanks,

Parge coat and internal insulation does seem the way to go. Are there any particular pros and cons between dot and dab insulated plasterboard and battens with slab insulation in between? More PIR or EPS or rockwool?

West Yorkshire

Thanks Declan. Building Regs are perfectly happy with 50mm PIR but with hindsight it just doesn't seem enough to me. The property is actually over three floors on a sloping site but in a chalet style. The top floor has one metre of wall before the roof structure. Nod, the other option I considered was dot and dab insulated boards, paying particular attention to sealing up around the bottom edge (continuous run of adhesive at the bottom and around door casings, switch and socket boxes etc?) I'll price up the cost of materials and the installation time of both options. I do like the idea of being able to run services along battens though without having to chase walls etc..

Thanks Joe90. Lovely part of the world you're in! Unfortunately I have been working abroad a lot this year and I fear that in my absence the cavity insulation (50mm PIR) may not be quite as complete and taped up as I would have liked had I been supervising. There are certainly a couple of other things I'm now wondering the best way forward on: 1: the internal blockwork leaf was not pointed so I have some gaps in the mortar which is not good for airtightness I considered wet plastering but I'm now wondering about battening the walls with extra insulation, taping everything up and screwing plasterboard over the top. 2: the roof is a very traditional slate roof on 6x2 timber rafters and steel purlins. It has been built as a cold roof so now I'm trying to figure out the best way of achieving a good level of insulation. The 1st floor is built partially into the eaves with the rest being loft/crawl space. Any advice is welcomed.

Hi, first time self builder here. Whilst everyone seems to be going timber frame, ICF, Passivhaus etc my build is a far more traditional block and natural stone construction. This has been a big learning curve and both my architect and builder definitely favour the traditional way of doing things. The shell is constructed and I will be moving towards first fix soon but I definitely have a few questions for the experts here along the way!