Nickfromwales

Rockwool fill, 40mm PIR, foil tape, then PB. You’ll need to manage the holes for lighting, or use a surface mount / pendant.

1300mm is plenty, you’d be ok at 1000mm tbh; if you're happy to receive ‘real world’ advice In-wall is fine, done this plenty of times, just a bit less ‘aesthetically pleasing’ to some. How so tricky? Have you not got posi joists?

The thinner the screed, the more likelihood of fractures (slight cracks) which over time could translate to visible failures of the tiles or grout. If it’s 40mm of fibre impregnated, cementitious liquid screed then you’re at the 49% club, if its 40mm of dry screed you’re in the 80-90% club; dry screed does not like going down as thin as 40mm, but you mention ‘poured’ so I’m assuming liquid screed? Then, if it’s gypsum vs cementitious, at 40mm this would have a reasonably high risk of cracks vs fractures imo, so I’d decouple as I can’t take any risks with clients projects. I’m also considering the repeated thinning out where the (?)16mm UFH pipes lay, reducing thickness to 24mm, linear to the whole length of each pipe run. That’s a significant, further compromise when looking at this holistically. If it’s fibrous, cementitious screed, then I think you’ll get away with having just a good quality flexible tile adhesive, with a min 6mm bed, laid over an appropriate primer (with the tiles being laid onto the primer when it’s wet). BAL do a tile adhesive that has (x)mm of decoupling qualities, like an ‘ultra-flexible’ adhesive. I always Ultra (Insta) products, never had an issue. Are you actually using ceramic tiles? These are quite feeble compared to porcelain, so with ceramic and the very thin screed I’d be saying 100% you should decouple. Points B,C,D, and E are all moot.

The only concern is 40mm of screed is as thin as it gets. That is the only reason I would suggest decoupling here.

And they deliver. Been using the one down the road for 20+ years, always great price / value, and stuff is usually in stock.

Is it cool in summer?

Yup. A pita to get a fitting on to, circa 20mm o/s dia iirc.

Why not use EPS instead of the RFG?

Draw some samples and get them to a laboratory!

You princess lol 🤣

Guilty as charged lol. The rubber bungs are very good, and have never caused me any issues, and I have used them for as long as I can remember. I would switch to 1x 50mm pipe / bung, and then T off in the cupboard for the two connections. I bring the 50mm pipe vertically into the bottom of the unit, then install a Y branch. Into the branch I install a 50mm cleaning eye (this will provide adequate rodding access to the 110mm pipe) and use the top of the branch for accepting waste water from the sink and appliances.

Expensive and laborious option? What’s the rationale for using foamglass? You can ‘plumb as you go’ and even have just one loop filled and working, as the manifold will allow you to shut off the ports for the future loops.

Sounds like grey water stink vs SVP “stench”. FWIW, the only smell that makes me being my lunch immediately back up, is when cutting ancient, blocked kitchen sink waste pipes out; the black sludge is just horrific, compared to a whiff of 💩. Do you have a pic of the plumbing?

Is there any known insulation under the existing floors, and what’s proposed for the extension floor? You’ll likely need to put pipe in at 100mm cc on the existing areas, and maybe 150-200mm cc for the extension, to balance out the difference in performance. Running the pipes in to Z2 is easy, just needs some sleeving over them where they exit the room, but why not have the manifold in the back of a kitchen unit?

Stench of sewerage? Is it coming back through the dishwasher?

https://amzn.eu/d/0ejwJXIa Lose the rigid one, and use the above to give you enough wiggle room to get these pointing vertically again.

I had it happen to me on a basement flat conversion, where I used a dense (kind of thermal) underlay in a room where the floor had no DPM at all (as I found out later) and it was literally soaking wet. I had to use SLC and a liquid (paint on) DPM to resolve that, but you should be seeing no such issues in a new build! Final test would be a core drill to sample a section of your floor to check the layers.

He loves it more than you do lol

64 million dollar question, without further investigation, sorry! You'd need to lift a section of flooring and get your hooter on to the underlay to see what's creating the niff. If it is the underlay, then you'll need a membrane on the slab, then EPS underlay, then the floor back down.

Yes, cement board can go over it if you want to render 👍. Use a combination of tile adhesive (cementitious) and screw fixings to install both of these two layers.

As above. It should be consuming moisture not emitting it, but the question is of how good a job has been done installing the DPM.

Post a link to the one you can get for £80, as there are different heights and variants. I’ve been fitting Geberit for nearly 25 years, with not so much as a murmur. Fantastic quality and unmatched longevity. Recently installed some Roca ones, very difficult to work on to access internal gubbings 👎

If its just rainwater, with no stench, then just drop the downpipe so its below grade and fit it into a rubber bung in a 110mm bend.

You either need a pump to ‘suck’ through a traditional TMV, or to get an ESBE motorised mixer to run off the heat pump. You never see the TMV after a pump, as it needs the recirculating water to function / reference the temp of the water in the loops. If you're having a TMV for Justin, you'll need to leave the manifold as-is.

For what purpose?