Mulberry View

Hadn't really thought of that, what's the concern from BC point of view?

I'll be very interested to see your scenario, do you have render over brick like us?

I would presume the renders will install a drip bead at the bottom of their work? If that protruded beyond the brick slip layer, would that be sufficient? Though, with that said, I wouldn't want to 'see' the EPS on the underside of the ledge (albeit tiny) created by the added EPS

Yes, these look good, but expensive. I'm pretty happy with how my Ledgers went in for the lower level, I'm hoping to do the same for the upper deck (roof), with the learnings from the first time.

Our external finish schedule is brick slips at low level, with render on the upper level, as per this detail. A local K-Rend applicator has told me that their build-up is likely to be no more than 8mm for thin-coat render. The slips are like to be in excess of 30mm, resulting in a more pronounced version of what our Architect drew. It feels strange to have the upper finish not overhang, or at least level, with the lower finish. Would you agree? What would the process be for adding, say, 30mm of EPS to the areas that will be rendered in order to create this effect? Would get rid of the need for the Aluminium flashing, would it not?

Would OSB3 be a good choice for a sacrificial floor? I'm expecting it to be exposed from now until about June/July. If so, could/should I apply an additional sealer to it to give it a better chance? I can get it for about £16+VAT/sheet for 18mm, so it's not wildly expensive. I'll need about 30 sheets.

OK, fair enough, but these fixings will penetrate the vapour barrier, will they not? Is this an issue?

As I said, the Zinc guy has offered to help me with detail drawings. In all honesty, he is awaiting our decision on colour, one we should have made weeks ago. If he's as good as he sounds, I think he'll be a goldmine of info once I get to that point. I haven't furthered to detail conversations with him yet, I will do that soon as we need to bump the date with him once more. The roof joists are not fitted yet, why do you ask?

@Russell griffiths I completely agree. Another of the mysterious unknowns that was apparently 'out of scope' for a £20k Architectural design package. I have good Zinc guy lined up. It's early days yet, but he's also a self-builder and has offered me lots of help with the details, so I'm going to sound him out on it as a first port-of-call. So many woolly details though, people have paid a quarter of what we did for their design and came out clearer than we are. If I had the headspace for it, I would like to employ someone to inspect our plans and critique the details to form the basis of a case against the Architect, but also as a way to know what needs sorting out.

@Russell griffiths, What is the build-up on top of the joists? Presumably you have a deck under the metal? Although I haven't looked at it in great detail at this stage, I have planned for a 6x2 wall-plate on top of the Nudura core, the concrete is 2" lower than the top of the EPS. The wall-plate will be bolted down and the top will be level with the top of the Posis. From there, the Plywood deck will sit on top of the Posi and extend out and onto the wall-plate. The Architect drew a timber upstand to the edge (4x2 timbers?). Though the mix of materials at the outer face does appear to be an issue (EPS, Plywood and Timber all reaching the outer edge under the render). I think this was not considered by the Architect. I am minded to pull that timber and the Plywood inboard by 50mm and add an EPS infill to the outside edge. Although there will be a join in the EPS, there won't be a mix of materials. The real-world implementation of that detail or a variation of it with the 5° roof angle translated to the timberwork is a little confusing. As is the fixing down of the timbers, these will evidently go through the vapour barrier. Am I overthinking this?! As an aside, I plan to amend the roof service void to 50mm as mentioned earlier and may/may not implement the service zone in the wall. That is to be decided on the basis of whether it adds to the u-value or might be better detailed with an additional internal layer of insulation?

I will not use Aerobarrier to allow me to be lazy on the air-tight details. I just need to know more about what is needed, I have the time and attention to detail. There is some great info in this post, for which I am very grateful. Reverting to an earlier point I had. How concerned should I be about the standard Nudura blocks and their u-value? What are Nudura doing now if the standard block achieves 0.24 yet current regs require 0.18? I am thinking of adding EWI, but this will screw up all my planned brick coursing and sub floor vent placement which I carefully considered at foundation stage.

I don't think that's a bad price really.

My architect specified an air gap, which I had suspected was to add to the thermal performance (as well as for services). Some on here said that it was not necessary from a service standpoint because services can of course be cut into the EPS layer. I do not intend to have the service void on the ground floor ceiling because it seems pointless with the Posis, but as I said, will aim for a 50mm void above the top floor ceiling. It's already been mentioned on here that the roof detailing is not ideal as it shows a mix of materials at the outer layer. My building is currently committed from an ICF standpoint, so I can't change that, but I'll be exploring ways to give me an EPS layer all the way up to the top of the outer skin. I think I'll be setting the outer roof timber and the edge of the Plywood deck 50mm back from the outer edge and adding an layer of EPS at the top. It's ironic because this could have been done with the Nudura but I built the ICF as drawn so that ship has sailed unfortunately.

Similar insulation levels to what I'm proposing then. The quoted u-value for the Nudura standard blocks is, I believe, 0.24, though I am told that things aren't this simple and that the individual components of the wall should be calculated and that the concrete brings its own advantage. In fact it was the relatively poor u-value that came to my realisation when Total Home Environment pointed it out as being probably the sole reason for my 'C' as designed SAP score. With that said, the as-designed SAP has window, insulation and air-tightness values that are easy to exceed.

I had presumed we'd fit 200mm of PIR. Keep in mind I haven't costed this up yet, so that might be where that decision changes. Budget is a whole other conversation, we're winging it in that regard too, though think we're doing OK so far. No spreadsheet!