Great_scot_selfbuild

We’re approaching the point of having the plumbing first fix done and I’m not getting the confident feeling from our plumber - they’re asking for the design of the plant room and system configuration. It seems they are skilled as the practical work when told what to do, but now I’m looking into what a design should look like. I’m not expecting our principal designer to provide a design of the plumbing pipework, and although I’m looking at alternative plumbers, I now want to see some examples of what to expect as to a design / configuration of the plumbing pipework. If it’s not that complicated (which I don’t believe our system is) then in order to get a neat and tidy install that we’re after, I’m wanting to work out a design even if it’s just a means of me assessing whether the plumber we contract proposes something similar or miles off. Help me educate myself - TIA

@garrymartin Out of interest, how is this calculated? In terms of ‘enclosed in insulation’, I’ve just been thinking this over, how enclosed is enclosed (if this makes sense). Our situation: There will be 75mm batt insulation in the 89mm stud walls (3m high), then cables running above the insulation in the ceiling space (425mm deep posi joists, with 100mm acoustic insulation), and then out into the plant room.

Mandated in our planning conditions - seems to be a default on all planning approvals from our council (not sure if wider as they all seem to vary so much).

Couldn’t agree more. I’ve yet to find an element of this project where doing some due diligence and checking of my own hasn’t thrown up very valuable questions or even identified glaring errors. I equate it to doing a QA ‘dip check’ and then finding I quickly need to ramp up to a 100% check 😭

Part of the challenge - we haven't decided yet, but equally this could change in the future anyway, so I'm just looking to install the wiring to be the most robust / good design we can. If it future-proofed the design I'd even go for 10mm, but if this is HUGE overkill and only really needed for industrial systems, then I don't want to waste the money. Based on me searches, I'm inclined to run separate 6mm radials. I assume a double oven is one (not two) cable, and a warming drawer is another(?)

I'm looking to make sure we document our electrical design and detail of all the layout. I have a very useable and functional method I'm using at the moment, but would like to know what it 'should' look like. We have a principal designer and this detail is exactly what I expect to be provided, but I'll be honest - on some of the nitty gritty drawing detail like this, I think it may fall short of expectations. Hence, I'm interested in: 1. Is there a layout / standard style that an architect would produce (to be clear, our PD isn't an architect - we couldn't afford to use our architect from planning phase for the construction drawings). 2. Are there other methods that anyone has found to be preferable / useful / look good. Thanks

We're laying first fix wiring with our electrician but the only size cable we have on site (at the moment at least) is 1.5TE (light), 2.5TE (power) and 3CE (blinds). I've not yet seen any radial circuits for the key appliances that I would expect to have on a dedicated circuit. Having done some searching and ChatGPT (but never fully trusting it), responses come back referring to oven/hobs on a 6 or 10mm2 cable and appliances could be on a fuzed spur from a ring, but radial is preferred. I'd much rather have more robustness in our design for the sake of a small cost of some cable whilst all the walls are open. Looking for a second opinion from those who know about this stuff. Detail: Induction hob, cable run = 25m double oven & warming drawer, cable run = 30m TIA

How are people fitting their MVHR unit to the wall? I’ll be unboxing ours this weekend and hoping that there’s some instructions inside, but I’ve had no detail on installation from the company (yet - have emailed, but waiting on a reply).

They are allowed as you say - confirmed by both my BCO and electrician (I got the idea from another build locally which installed floor sockets).

That would do - I didn't know how much the edge needed to be left floating/free to move.

Are you referring to the doormat issue, or are we going to need a trim for getting flush to the sliding door / window (i.e. can we not get the flooring to be flush to the edge)?

Any advice / experience on laying a floating floor LVT system. I'm aware of the requirement to leave a gap at the edge underneath skirting board, but we're wanting to have it flush at a couple of locations. Would appreciate advice on the following scenarios: 1. Flush/right up to the edge of the sliding door and windows which make up 3 sides of an open plan kitchen/dining room (all other edges of the flooring will have a gap around the edge concealed by skirting). 2. Flush up to a well mat at the front and rear doors. Can we take it right up to the edge of the mat, or is there a trim that would neatly act as the edge of a mat well and provide a cover over the edge of the LVT? Thanks in advance.

Concrete beam & block, 150mm PIR, UFH in 75mm screed, LVT to finish

How deep into the PIR should I recess 20mm conduit for in-floor plug sockets? Any tips on cutting the PIR? I’m assuming I cut a square channel with a thin layer of PIR over the top of the conduit just so the UFH pipe isn’t directly on the conduit.

Thanks all - the fit is pretty good tbh

I’m busy installing PIR flooring insulation (on top of beam & block floor, to then have a dry screed laid on top. We have the DPC down, and it’s all going together fairly well. I understand expanding foam is typically used to help fix them all together and generally fill the odd gap (none are large). I’m worried about the foam getting underneath and lifting the boards. 1. How much foam is typically needed (assume the sheets are tight together)? 2. Any tips on installing the foam? 3. Do I need to be worried about the foam lifting sheets, or will it only really expand where there’s a gap for it to? TIA

Great to hear. We've had our Internorm door fitted and LOVE it. Definitely felt like a luxury spend, but we went by a similar logic - few bits of the house will have such a guaranteed impact. No fingerprint scanner though... 👏

@SimonD I'm interested in doing my own calculations on this. Whilst I head off and do some searching, can you help me expedite this by directing me to any resources / reference material that takes me through the process specific to sizing UFH to a room / heat loss etc? It sounds like this should be a lot easier than trying to dig out my thermodynamics notes from 20+yrs ago (I hope... never was my favourite, but now I'm more motivated 🤣). In an earlier post which evolve into a focus on the UFH layout / sizing I had actually asked about this - I was wanting to understand if I should be looking to tailor the UFH pipe spacing and design to each room, which largely received the response "it'll all end up at the same temperature, so don't bother" (I'm heavily para-phrasing). However, I do like to learn a new aspect of engineering and although I have no available time, I'll happily sacrifice some of my sleep to work this through myself. Would be grateful for a steer... (btw I did look up Rob Berridge and in the YouTube interview he mentioned that he provided training material but I can't find it; I've reached out to him, but no response yet). I'm still waiting myself. This sums up so many of my frustrations. How are the general public (i.e. me) meant to know enough to challenge the information we're provided. I've surprised myself at how much I've spotted, been brave enough to question and then, disappointingly actually, found out I'm right and something needs to be changed or corrected! (from architect designs, timber frame structural elements, roofing construction and roof light installation). Micro rant over. Thanks for this - I will be re-visiting the ASHP / heat loss calcs (though I know it's 'just numbers plugged into a software tool' - hence my interest in learning the calcs).

Well I have been pleasantly surprised by the UFH supplier - they understood my request to increase the spacing between the supply / return pipes, replace the utilities area and have re-done the design. Where they're still bunched close, I'll insulate so that there is an exposed pipe every 150mm. Here's the revised drawing for those who will be interested. UFH-FHW CAD Drawing Rev 2.PDF

Great to hear - thank you. Our ASHP installer is complying with the MCS requirements (which doesn't allow MVHR to be taken into account, and only goes down to 35deg flow temp), however, he knows exactly what we want and, importantly, he has done exactly the same in his own house, so there's making sure it can achieve the MCS sign-off, but able to modulate down low enough to run efficiently as very low flow temp. They even audited his house as luck would have it and it still met the requirements for the BUS grant, so after being initially frustrated at the MCS / BUS restrictions, I'm happy I've found an installer who understands how to comply with it whilst delivering what we want.

They knew exactly what we planned to do and we gave a very clear requirement. I'm getting very used to this 'quality' of output from the suppliers / distributors etc. now though. Speaking to my builder, it's entirely 'normal' and he spends a large amount of time fixing design issues on site. Unfortunately it also only works on windows and I'm loathed to by a PC or try and set up a virtual machine on my Mac just for this; this was why I went with a supplier who would be paid to do the design (having provided them with all the necessary information). #sigh... Is this a personal recommendation of this one, or has it turned up on a search (just wanting to make sure I understand before I look around). Thanks for the nudge. This is a good enough reason for me I think

@Susie Thanks! - photos of it in use is really helpful. We have spoken to countless people about the screed options and I was surprised that I have been advised that for dry screed (which were going for) we don’t need a membrane/layer on to[ of the PIR insulation as, although it’s pumped in, it’s simply not as runny as liquid screed. What type of screed did you lay on top? Either way, I like the approach of using the grid membrane @torre included a link to. Our ASHP supplier is working on the heating load requirements, and the UFH supplier providing the UFH design. I’ve asked for the additional design information beyond just the drawings, yes. @JohnMo 🤣 they’re welcomed! 🙏. Posting publicly is always a risk, and sometimes the best comments are those that challenge your (my) current position, either to present an alternative not yet considered, or to make sure the path chosen is done so in knowledge of the risks/compromises (which there always are), so thank you - very much appreciated 😁. 1. I have wondered about this - why the runs to/from the loop aren’t also spaced as the same as the heating yrs serving the same function after all. I’ve not had any design / response look any different to this (nor seen ones do it in the photos I’ve seen on this group - they’re all bunched together in getting to their destination). I’m going to ask I again, but have low hopes that they’ll have the skill or wherewithal to do that. I’m getting used to the professionals’ not living up to expectations, even when they just specialise in that one aspect of design. 2. Noted. 3. Not sure I understand what you’re saying? (FYI the whole downstairs is single zone, and provides heating up through void in hallway for upstairs). 4. Manifold is in the utility, yes. This is the first I’ve had anyone mention insulating pipes, though it makes perfect sense - can you please elaborate? (Photo appreciated, to help me interpret what this looks like before screed is laid on top). 5. Yes, and yet this seems to be the way the industry operates. I approached quite a few M&E firms but the prices were quite ridiculous. Would be ha[py to pay a reasonable fee, but not how they marked everything up and tried to oversell. Rather made me very sceptical about the whole lot tbh (on top of me having to correct some of the professionals I have paid).the spread of inputs from this group helps me balance out the options and weight it all up. I agree, it isn’t a design.

Thanks - I had read about this. I’ll DM you 😁

@Barnboy that is exceptionally helpful, especially with the photos added - very much appreciated. Chalk line ordered!

Given the challenge of getting a UFH design done, now that we’ve (eventually) selected our UFH supplier, I thought I’d share the layout design they have provided. I had requested a spiral pattern and first time they sent over a serpentine design. I’m pleased I checked it as soon as it arrived as they they re-ran it and sent the spiral pattern, but I do like having both as a comparison. We will be installing the pipework and now that we have a design to look at I’m interested in hearing advice on how best to tackle (practically) the layout. I’m purchasing a UFH staple gun and decoiler for the pipe. I’ve got a couple of weeks before we start this. My initial thoughts are to mark out 150mm spacing across each room in both directions (partly to double-check the design), and lay the longest loops first. Spiral configuration that we’re installing: Close-up of the longest runs: