Tom

Thanks for your input both. I guess the issue with the I beams is I don't really need a big span (max 5m) - and they're going to come in more expensive than normal timber. If I go for the composite panels on purlins at the moment that seems cheaper than I-beam/timber rafters - and I've immediately already got a U value of about 0.17 with the 120mm PIR in them. Then I would fill the void created by the Z-purlins with say 150mm-200mm mineral wool and the U-value would be down close to 0.10. Tell me if I'm talking absolute bollocks!

Got some more info on the composite panels that I can ghet for £15/m: its Tata Trimapanel, which is a flat composite panel actually designed for walls it seems. As I'll be covering with another layer of wriggly tin I guess they would be usable on the roof. Anyway, SE looking at it now.

Thanks Russel. The roofs have a maximum span from wall to ridge of 5m, with angles of 14, 22 and 23 degrees for the three different roofs. Floor plans attached to show how they are arranged, the largest and smallest "barns" on the right and left respectively have their ridges running vertically up the page, the middle barn has it running horizontally - hipped where it meets the larger barn, and gable end and valley gutter where it meets the smaller barn. It's all single storey with vaulted ceilings.

Thanks all. Trussed roof not an option unfortunately. Hadn't thought of the I-joist/posi rafters. Essentially the costs would be similar to the standard cut roof as a whole I guess, except more for the joists themselves - online it seems like they are approx £10/m? Are they worth the extra? What makes them outperform traditional timber? We're not so bothered about routing cables etc as ductwork will be external.

Hi all. So, finally, the jokers who put our Nudura walls up have finished and I have a really good builder lined up to start the roof in about 4 weeks. The problem is I need to finalise exactly what structure the roof will be. The building has 3 large elements to it, all single storey with a total of approx 360sqm of roof. It has been designed as a cut roof with insulation of mineral wool, the final covering will be corrugated metal. It is designed with steel ridge beams ( two steel rafters to split the longest of the 3 roofs) and lots of rafters in 8"x2" timber. The reason I'm waivering is over the cost in materials and man hours to do this and of course factor this against achievable U-value, and the builder we have lined up has lots of experience with industrial builds and is recommending going down the composite panel route. The options I can see we have so far are as follows: 1. Cut roof. Costs: approx 900 linear metres of 8x2" at approx £4.50/m (from TP) = £4000 mineral wool - 200mm thick approx £5400 for 360sqm 18mm ply sarking - £30/sheet would be £3,750 battens and counter battens membrane corrugated steel at approx £20/m = £7,200 a lot of man hours to cut and fit joists (total approx 190 timber joists) probably a lot of scaffolding U value? 200mm woool probably not enough 2. Composite panels. Costs: redesign of roofing steels to incorporate a few extra steel rafters and Z purlins composite panel seconds that my builder can get at £15/sqm (120mm thick PIR)-= £5,400 approx, these are in box section, so would need to cover roof with ... battens corrugated steel at approx £20/m = £7,200 fewer man hours, could potentially be done in the building with a scissor lift rather than scaffolding U value: 120mm PIR plus 175mm wool 3. SIPS Same costs for the steels, purlins etc as composite panels, still awaiting a quote for the panels again, much fewer man hours, less scaffolding etc 4. Thermoroof self-supporting EPS panels Same cost for the steels and purlins as the above two options quote received of approx £25k for supply of 360sqm - which makes it about £70/sqm, quite a bit more expensive than the composite panels at £15/sqm! Another cost to factor in would be how the internal finish would be done. Cut roof can have vapour barrier then just PB or even a thin layer of PIR taped to add more insulation and act as a barrier. The composite panels would need some internal timbers fixed to the purlins to board on to I guess. I know there will be lots of other costs I must be missing, but I just wanted to get something down in writing and out of my head. Hopefully then I'll be able to sleep tonight - and hopefully I can invite some comments/voices of reason to help me see a way through this. Can anyone give any advice re the above?

Long shot I know, but does anyone have an off-cut of this going spare? I need a 250mmx250mmx20mm piece to go under a steel column, but there is a £100 minimum order from them! Thanks all...

Paid by BACS a short while ago, then just now got a text from HSBC saying that if I don't verify the transfer they will assume it's fraudulent and recover my money! Wish they would do that with my council tax...

Can't pay anything by credit card unless they take credit card payments Long way to go until I get in to my overdraught...? lol

it seems they don't?

OK, thanks all for the above. Will stump up the dough. As an aside, I'm about to pay the deposit for our sliders and I want to pay part of this by credit card so that I am covered under section 75 - but they will only accept payment by BACS or cheque annoyingly. Am trying to confirm with HSBC whether I can send a BACS payment from my online credit card account...

Hi all, our front door supplier (supply only) is insisting on charging VAT, saying I can just reclaim at the end. It was my understanding that they are legally obliged to zero rate if this is a new build though. Fine, I guess, if we can reclaim at the end - but could there be a problem if we try to do this?

...and the manufacturer adds a nice mark-up. Firm handshakes all round and guess who pays...

That's useful to hear your experiences, thanks Ian. It does sound like it could be an issue, but I suppose I'm erring on the side of without, as I'd prefer not to look through tinted glass and rely on removable things eg shutters or the venetians you suggest, to use as and when needed. I guess the external film is removable? So could put this on for a few months then remove for the rest of the year?

Aha, good point ?

We will be putting in a long run of sliding doors in a south/south-east elevation - total length 10m x 2.4m high. How important is solar control glass? I was about to pull the trigger on a quote and noticed this wasn't included and am now in two minds whether to pay for the extra. The room where these are is quite large - 18mx9m with a vaulted ceiling up to approx 5m. What factors are important here? We plan to have sliding shutters on the outside of these doors (like timber-clad barn doors) to help with the solar gain. Looks like visible light is reduced by 30% too which isn't great. If the consensus is equivocal I'd probably go without, but given the amount of glazing I'm having second thoughts. Any views? Thanks all

I've always blunted nails with a tap from the hammer before using tbh, can't remember where I picked up the habit but good to hear I'm not the only one!

Thanks for your input both, apologies for my late response. Build is ICF and highly insulated, heat source: ASHP. 300mm EPS below warm slab, UFH pipes within this in the living area - polished slab as the final floor, pipes in screed over the top of the slab in the bedroom/snug etc areas - with mixture of tiles/carpet/wood floor finishes. I'll see if I can ease the congestion in the corridor - but I guess from your observations I could get away with uninsulated flow/returns as long as they are at 150mm centres - esp if temps are going to be low as ragg987 points out?

Great, many thanks for you reply. The pipe is 16mm by the look of it. I agree with your idea re the en suite, would make sense to have a floor probe here. The quote includes 12 actuators - so I guess they planned for the manifold for the main area to be without them (the actuators being for the other manifold) - I don't understand what a 2 port zone valve does, can you expand? Why would you recommend this for both manifolds? I could also run the loop for the spare beroom directly through the wall in to it, so reducing congestion in the hallway a little. Re this congestion, they suggest using insulation around the return pipes - is this necessary? What insulation should I consider?

Don't forget to think about how you are going to brace the ICF - we are using Nudura and it needs bracing against the floor with props which need to be bolted down. If this is in to your final floor finish (albeit before the final grinding perhaps) could mess things up a bit. We are having the slab as the final floor finish in the main living are of our build so have poured small strip footings within the walls to take the bracing. Obviously not an option if you are doing a raft.

Morning all - received the attached from WUNDA yesterday. Are there any obvious errors/improvements that you can see for this? I suggested to them that we could have the pipes for the main area on the right punching through the plant room wall beneath the fish tank (marked "6" on plan), but they seem to have put them through the wall in to the corridor. Also, the manifold for these pipes is in a different position to the other, which seems odd - but perhaps that's OK? I'm expecting to have the UVC etc on the left hand wall of the plant room - but haven't spent any sleepless nights worrying about this yet, perhaps I need to start. Anyway, would be very pleased to hear any feedback. Pipe spacing's are 150mm. Cheers all 05054 Tom PIPE LAYOUT - A1.pdf

It does, Gus, many thanks. And thanks Conor, Dave and Jonny. So, approx 6 hours to go until the next issue bubbles to the surface in my subconscious...

Hi all, latest one waking me at 4.30AM: do we fix our sliding door headers directly to the cantilever steels - or do we fix eg some ply to the steels then fix to this? Or possibly some thermal break material (armatherm or similar) to the steel instead of wood? Slider's are these: https://www.cortizo.com/en/sistemas/ver/93/cor-vision-plus-sliding.html Below is the detail from the architects, so looks like wood or similar between the header and steel, would be good to hear what the consensus is. door header detail.pdf

I'd say Internorm are more composite than merely "aluminium clad". There is lot of external material there until you actually get to the wooden element. We looked at Nordan and that really was just clad it seems - some very thin pieces of aluminium laid flat on the wood. The Internorm was very solid and seemed in a different league. A bit like calling all wood flooring "laminate", like lots of people do.

Taping the PIR means you can make holes all over it (as long as they dont pierce the foil on the reverse) and it will still function as a vcl, no need for anything behind it.

I'd swap bedroom 2 and the office - less chance of hearing your guests snore.