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FWIW, French regulations specify a maximum of 250mm between pipes - more here:

When I studied construction - when there were very few building physics geeks - the library had a whole bookcase documenting experimental buildings technologies that people had tried in an attempt to live off grid or cut their energy bills (carbon emissions weren't a thing). Trombe walls, solar hot water (usually using salvaged radiators), solar chimneys, superinsulation, earth sheltering, water powered generators and plenty more. Most of the people only had a rough clue about what they were doing and how well it would work, not much idea about what to prioritise, nor whether any of it made economic sense. And intuition was the only way of knowing whether or not a brilliant idea from Arizona, Tokyo or Stockholm might have any relevance in Abergavenny, Brighton or Clydebank. The revolution that PHPP brought to this jungle shouldn't be underestimated. It's difficult, for example, to be a member of this forum without knowing about the key ideas it helped popularise - such as airtightness, MVHR, superinsulation and triple glazing - even if there is a case for prioritising ASHP, PV & battery storage (at least in Ireland).

Was that coloured glass then or did you manage a neat job with the sealant?

I did that in our previous house. I got a piece of glass cut to the exact size of the top with a central hole cut, sealed the edges with silicone (handn’t heard of CT-1 at that stage). Never had any problems with condensation or water tracking underneath in the 10+ years we lived with it.

That's a though for water condensing on the basin and running down onto the top as well.

The calcs need to take account of what's going on top of the rafters, of course. I was having a Gemini AI chat about a workshop with a flat roof & proposed 6.5m span, about a week ago. Gemini recommended reducing the width to 6m internal so I could use 47 x 220 C24 at 400 centres to save a load of money against the next size up, in C24 spec' (THIS WAS MIS-INFORMATION). The same chat gave this link for a span calculator, which shows that 47 x 220 will not be good enough for a 6m span. https://www.timberbeamcalculator.co.uk/en-gb/span-table/flat-roof-joists?load=0.75&class=C24

Depends on the depth of pipes, ours are in 100mm screed and there is zero. So thats should not be a concern. Even when I used the boiler at 34 degs there were none. 300mm is generally fine, one thing it does bring is a fall off of heat transfer at very low flow temps, so to counter that on 7 to 10 deg days I just flow at 29 and in Cosy periods and the runs are good. Have a WC curve that runs 29 to 32 (10 degs to -5 degs). Running 29 degs gives a very stable run time of over 3 hours and also excellent CoP, just finished a run I did as I was getting free electricity, ran in manual for 3 hours and got a CoP average of 6.6 at one point it was doing over 7. At 300mm spacing you can very easily hit very high room temps, just flow too high for too long and you go into melt down. Just use the chart I posted on 30 Aug to work out how little flow temp increase you need to add to increase output hugely. If you are concerned just drop the spacing to 200-250mm, but tighter in bathrooms due to the limited floor area

An idea: How about removing the top wooden surface and putting something like quartz or corian on it? Keep the rest of the unit as is. That's about as bomb proof as you are going to get. Pricier than glass but you might find a keenly priced offcut the right size. Something like Corian can be cut easily. Does change the look though so maybe not what you are going for.

It is quite a piece of work to create a meaningful budget and to stick to it. Our original builder had a QS draw up a line item budget for our extension/refurb contract but with estimates for the plumbing and electrics. I insisted he got quotes for those items which came in a lot higher than his estimates. You need to either have a pretty good idea of what you want to do and the relevant prices, or be defining a budget and then constraining your choices to fit within it. These days there are lots of items where choice and affordability can change the price by multiples and huge amounts of that choice. You should have a window and door schedule and cost that up, a steels and lintels schedule etc etc. You are bound to want some labour too I'd have thought - some things require multiple people, some particular skills, or placing risk with contractors. As it's your forever home you will need to phase it appropriately. Are you going to be living there, or when would you need to start living there ? Living on a building site is not much fun, but makes it easy to be around as much as possible. Are you trying or willing to do it over 1 year or 5 years or even 10 years ? Do you have a partner ?

It's not just water getting underneath; it's the temperature differential too. Just think about what happens to a mirror without a demister. Do you want that for your flat surface?

That would have worked if it had been designed in at the outset, but that will mean changing the orientation of the joists which in turn will probably mean that the inner leaf steel for the large garage door opening is now not adequate enough to support the loading of the joists that are not resting on the blockwork above.

🤣 Definitely not 1. Glass is a good protection surface, not sure I've heard it done in a bathroom and fear water getting underneath (which would likely be a worse problem than not having the glass if you didn't notice it - and it's a pain to get at once everything is finished). My initial thought was a good application of latex type paint. Not waterproof but kinda close if you are good at keeping things relatively clean and hopefully moves with the wood. However, given your first statement, if you expect a collection of objects to accumulate and therefore maybe spills to get missed in the clutter I doubt it's a good idea. I've no practical experience doing something like this so just thinking aloud.

The amount you've got down for bathrooms doesn't really allow for much more than the most basic products (and it's tight even then). When it comes to choosing fixtures and fittings you may find that number going up quite a bit.

A steel midspan might allow the existing timber you have purchased to be used.

We have used the HiTherm type lintels on the < 2.7m spans, but for the 4.8m / 5.7m openings we had to conventional steels. Hoping the SE can come up with a solution and I can try and get a metal fabricator to site to perform the required welding.

The boss has asked for the arrangement below in our en-suite. Once installed the detritus on the top will be replaced with hers, but hopefully less. It's an 1150 x 450 console table with two drawers and an Ikea Tornviken basin on top. I have already cut the required hole in the top and adapted the drawers to accommodate the trap and tap tails. Given the arrangement, I am concerned about water splashes going on the table top and ruining it. We've thought of various options to address this: Sticky furniture vinyl [d-c-fix], but I worry it would peel in time and look bad Liberal coats of yacht varnish, the wood may still move in the humidity and crack the varnish A glass table top with hole cut in. If see through (~£50), I wouldn't be able to seal between the glass and the wooden painted top. If the glass itself is painted on the back (kitchen splashback, ~£125) it could be sealed. My preference is [3] and I am thinking 8mm or 10mm thick toughened clear glass with a 10mm overhang to try to stop water tracking back and between the glass and the table top. Does anyone else have a good suggestion or experience with a glass top in a bathroom?

"Think you need contingency regardless" - Fair point! Ive added 10% contingency but in reality, its my forever home (answers your other question ) so I'll spend what needs to be spent, it will just mean delay until we save up the shortfall. "How would you phase the work ?" - very good question, we are hoping to start upstairs and get that in a good state. Then we will tackle lower floors and bathrooms incrementally, keeping the mess contained. Definitely not figured that out yet but need to have a game plan. The app I use has a Gantt chart and tasks feature so I can plan what needs doing, assign materials to tasks and ensure I'll have enough to cover each task. Electrics - Doh! Thanks, forgot to add that.

Thanks for your input, good points! The skirtings appear to be in a good shape, could do with sanding and repainting. I'm giving myself 2-years as I have a 3-year old, a baby on the way and a full time job 😅 So will mostly be evenings, annual leave and weekends.

Yes, lap it with the lower DPM under the PIR. That's your actual damp proof layer and the one that should link up with the DPC, so the EPDM under the threshold needs to be continuous with it. The slip membrane over the PIR is just there to separate the screed from the insulation and stop it running into the joints, it isn't doing any waterproofing. Where you can, lay the lap so the upper sheet sits over the lower one, so any water that does get past the threshold is shed down onto the DPM rather than behind it. Then turn the slip membrane up at the edges behind your perimeter foam as normal. If the DPC detail at the door is a bit unusual, worth a quick word with building control so they're happy with it before it's covered up.

I've just received the first draft of a more thought-out UFH layout. The designer has gone for 300mm pipe centres. It looks (worryingly) simple! I've raised concern about heat striping, I don't really want to risk that. He has gone for 3 manifolds, one on each of the 3 ground floor levels. 2no 2-port manifolds and 1no 6-port. I've proposed and idea for 2 manifolds and have fed that back. He has suggested that 20mm MLCP for each manifold is sufficient, something I've probed on because it seems very small. I'll share the design once I have it, but I am minded to want closer pipe spacing as I'd prefer some headroom. Not least in case I can't hit my desired ACH. I'd rather have more pipe and have to control the flow temp than find it's just weak performing.

With the integrated fittings, if they are discontinued or you alter the kitchen you may not be able to get the right lengths. Make sure they are able to switch from the same place as the rest of the lighting.

I have seen these where they are bolted together on site. One of the lintels has some tube / chs welded and the 2 are bolted together. Needs SE design. If the cavity is 150mm or less you can use the HiTherm lintels. Expensive and long lead time on some, but good psi / thermal bridging characteristics.

Nah, Pedal Electric is... and 15 minute urban planning.

When planning LED lighting under kitchen cabinets, there are a few details that seem worth getting right before the units and worktops are finished. For a neat installation, how do people usually plan the driver location, cable routes and access for future maintenance? Hiding the driver inside a cupboard can keep things tidy, but it still needs to be accessible if it ever needs replacing. I’m also interested in the practical differences between fitting LED strip in an aluminium profile with a diffuser and using ready-made under-cabinet light fittings. Is the profile approach worth it for better light distribution and heat management, or do integrated fittings tend to be simpler in the long run? It would be useful to hear what has worked well in real kitchen installations, particularly when planning everything before the cabinets go in.

I have asked the SE for her PI insurance and have finally managed to get her to answer the phone and agree to a site visit. Builders are not happy with the arrangement of the separated internal (C section) and external (Non equal angle) lintel specification. The two sections are not jointed together (yes, it mitigates cold bridging), but builders have told me that when they recently did the same thing on another job, the brickwork above the lintel all cracked. Having been outside to look, it's quite easy to see how the external L lintel just wants to topple backwards into the cavity.