Mulberry View

I'm sure my proper UFH design will uncover that 40w/m2 is far too much. See my reply to @SimonD below. Thanks for your input, BH has been great to me, the support is helping me keep my head above the water (just about!).

In fairness, this is an outline quote, we're not at design stage yet so a set of heat loss calculations has not yet been done. I guess they'll charge for that in the end? I'm trying to do that myself through Heatpunk, but it's tricky with my very irregular shaped house. I'm considering paying for the Pro level for a month or two so I can upload my plans! But that doesn't help with ceiling levels (I have sloped ceilings). I haven't added all the windows yet, but it looks like 21w/m2 on there at the minute.

Thanks for this @Gus Potter. I'm a very very patient guy. I am possibly too far into the details, but I gave this guy so many chances, we communicated loads. I provided additional photos and dimensions as were needed to articulate the as-built structure. I spent FAR too long trying to mock layouts up in ChatGPT to try to further illustrate points I felt the Architect had missed. The fundamentals were missing though, without adherence to the standard details of the roofing system, we needed to go all the way back to square one and the passage of time thus far made it feel too risky to do with how weakly applied this guy was. With the idea that the ZInc roof needs to be stripped, part of my brief was to try to retain the Plywood deck if possible, as "taking the lid off" and seeing daylight from inside again felt like too much regression and another layer of waste that might have been able to be avoided. I already have 170sqm of 200mm Celotex that I cannot reuse. This might be why he couldn't have oversailed the edge to provide a similar detail as the one you kindly posted. I also now realise he's not as experienced as I initially believed. Keep in mind the total quote was £4000+VAT. FOUR THOUSAND POUNDS to provide a set of 6-8 details. Many people do not pay this for their whole Architectural package. I was desperately in need of help and believed this guy could take some of the stress off my shoulders. Turned out he just added to the ever-growing pile of nonsense that we're battling. We've lost tens of thousands of pounds in this project on "leakage". Poor Architects and this whole roofing debacle being at the forefront. Those elements have BY FAR been harder than physically standing this place up, even at my experience level. Some of the things I have achieved in this build make me proud, dimensional accuracy, level and having 3 ground floor levels that are +/- 10mm from the planned levels being some of them. Why can't professional services take the pride in their work as standard and just do the right thing if the customer isn't happy (and brings justification)?

Sadly, to our detriment, we do not have legal cover. This emerged during the early stages of the legal action that is still ongoing with the defective Zinc roof. We live and learn!

Although I need to look more closely at the quote, they've based the whole-house design on 40w/m2. I'm guessing that 10.5mm pipe at 75mm spacing is similar output as 16mm pipe at 150mm spacing. You're right though, this is more to give a warm feeling to the floor and what little bit of heat input might be needed.

Yes, they prescribe 10.5mm pipe for 17mm total, or 16mm pipe for 25mm total. I'd like to try to make the UFH/Screed/Microcement layer compatible with thick carpet/underlay in adjoining room, so figured that 21mm total would work well against underlay and carpet. We don't need loads of heat in there. I also have a floor to ceiling window with only 50-55mm of frame to play with. The 10.5mm pipe solution gives me 41mm, the 16mm pipe would be 51mm.

The only issue for me is that I can't accommodate that thickness of screed. However, I could go for a "halfway house" with the Roth system and their fibre reinforced liquid leveller (or another similar product), which they rate at 17mm total system thickness, so it'll be a few mm thicker by getting rid of the plastic grids. That's obviously not 16mm pipe though.

Interesting thought. Seems quite reasonable. Are the grids just for installation convenience? As long as the Chipboard is sufficiently waterproof... Is that a Chipboard floor with a DPM then UFH pipes?

You'll notice from my wording that I said "I wondered". It was a fragment of my own uneducated thought process.

That's all very helpful. My small first floor is designed to have acoustic insulation under it, but I also realise that will block some of the heat rising from the ground floor. I had, however, wondered whether it might be a good idea to add some sort of reflective layer between the Chipboard and the "egg crate" system, what do you think?

I agree with that sentiment, I'm the king of overkill, which is why I have 253x145 joists at 400 centres under this bathroom, with a 5m span and strongbacks in there too. It doesn't budge.

Egg box overlay? So like this??... https://www.roth-uk.com/products/low-level-overlay-system/roth-quicktemp-climacomfort-system That system has as low as 17mm total build-up when using 10mm pipes at 75mm centres and their fibre-reinforced leveller. Forcrete Microcement could, I think, go directly over this and the 21mm height off the top of the Chipboard would work well with the adjoining carpet/underlay if we go that way. My Ensuite is a reasonable size (around 3.0x3.0)

Following on from our Architectural woes (we had to part ways with our original Architect). I instructed an Architect to handle the re-detailing of our roof as the Zinc scheme that was installed 2 years ago has to be ripped off. The assignment was a fixed scope, to provide replacement details to cover all areas of the Zinc roof but with Sika SGK membrane, I had obtained a spec from Sika which was in hand. I was very open and candid about the as-built structure and the pain points. I provided lots of photos, plans and a detailed narrative all in advance of the quote. I explicitly told him that I needed decisive details, as I don't have the headspace to do this myself. The Architect quoted, I agreed and paid 50% up front as requested. The suggested timeframe was 4-6 weeks. It quickly emerged that the Architect was not confident. He flitted between solutions and relied upon me far too much to back him up. 5-6 months later, we still did not have a workable set of details that were efficiently buildable and conformed with Sikas standard details. After much patience, I called a halt and raised a dispute. After some backwards and forwards emails, the Architect has agreed to waive the remaining 50% fee, but insists that the 50% up front is payment for time spent. This is an example of the details produced... There is far more timber in here than the alternative detailing and much of that is not practical in my view. Besides, the Aluminium edge drip trim arrangement doesn't conform to Sika's detailing and for their own trim that is the only one they allow. This is the alternative that I now have in hand (not quite finished but you get the idea). Far simpler and compliant with the manufacturers requirements.... As I understand it, payment for time spent is not a thing with fixed-scope/fixed-fee work? Nothing about payment for time spent was discussed in a email "contract". I have nothing usable from his detailing and have since found a good Architect who has already pretty much re-detailed it proving it can be done. I'm not prepared to let the £2400 I've paid this guy just slip away. I'd appreciate any advice on this.

We're building a 200sqm Nudura house, around 135sqm gross ground floor, 230mm PIR over B&B floor. In-screed UFH with around 50mm of liquid screed is looking likely. First floor is just a Master Bedroom, Master Ensuite and a second Bedroom with a small Ensuite, around 65sqm total. We like warm floors in the Bathrooms, so are thinking of going for Roth Clima Comfort mats with 10.5mm pipe over the 22mm Chipboard, their liquid screed over that as it'll make a nice substrate for the Microcement (that SWMBO simply will not compromise on). The Bathrooms are back-to-back and the Posi design is super-rigid. Does anyone have experience of this type of system for first floor? I gather we have to have some sort of emitter in the Bedrooms to qualify for the BUS grant? But we want nice carpets (not limited to 2.5tog), so the option I guess is UFH and just accept the performance loss (the heating will be minimal anyway) or fan coils, but we lose wall area with these I guess? I realise the upstairs heating is debatable for most people, but I don't think we can go for no heating at all up there, I'd hate to have to do something retrospectively. Also, what type of pipe? Roth have quoted for PE-RT (they have an Alu option but say it's overkill), Continal suggest PE-RT/AL/PE-RT....

As a follow-up to this, I replaced the PRV (cost about £20 locally). Really was a pretty easy job, certainly isolating and draining the boiler was the tricky bit but only because I didn't have a suitable piece of hose at first to allow me to drain the boiler into a bowl/sink. I repressurised the EV. This was about 2 weeks ago, the system is still holding 1.5bar. I'm sure I'm not in the clear, but it seems OK. So we'll see how it goes. Thanks @Nickfromwales