Mulberry View

I greatly appreciate all replies on here, well except for @Dave Jones. Firstly, I am the 'builder'. Nothing has been butchered, I take great offence at that. I have also not improvised. The whole scheme is installed to the absolute letter of the structural design and this mindset is what has led to this post. I am concerned about deviating 'off plan', but I don't think the Architects plan has been thought through. The Ledgers are mounted to the ICF with pairs of M16 bolts at 800 centres and with concrete pads directly through to the back of the timber as seen here. This was agreed with my engineer. The Posi scheme was designed by Pasquill and meets <10mm deflection limits. I have a designer there who has been exceptional and we have carefully examined every detail as I wanted to understand it all. I'd be keen to hear what you think has been butchered as I take great pride in my work and strive for perfection. I know you're a great contributor here and take all (most) advice on board with great appreciation, but I'd love to see/hear some substance to your suggestions as you've added another layer of worry at a time when I could do without it (unless its justified of course). @ETC and I are chatting in DM's. I am beyond grateful for his input and he knows that.

Yes I know. We might end up with one on a little garden building just as a feature to keep 'er indoors happy.

SWMBO would KILL for a rain chain. Honestly.

I'm starting to think the same way. It's a short section (around 1200mm max), we could have a nice gutter and downpipe on that side. That wouldn't bother me, I guess I just need to understand how the edge would be detailed and if that would look OK.

I'm starting to think this roof may have to be open and into a short gutter. I'm fast running out of time.

Would be lovely to gain that much space back, but what about the insulation under the VCL? Everyone seems to say that's a no no.

Indeedy, and the fact that I am facing this problem doesn't write the whole design off. As someone who is not a 'tradie', this has been an ambitious build and far harder than a straight-forward square/rectangle building would have been, but that doesn't take away from how pleased we are with how it is turning out.

Dave, again, please stop posting here. It's not helpful. The fact that you think those 2 roofs should be joined shows that you do not have a good idea of how the design works and therefore should not try to give advice.

Am I right in saying that a hopper could only be used with a parapet wall in this scenario?

@ETC My sketch is getting a bit ugly now I'm tippex'ing and scrawling, but what would be the effect of reducing the insulation on the flat roof to, say 150 or 175mm when the rest of the house is at 200mm? If I could do something like below, with 100mm base layer of PIR forming the bottom of the gutter and the Parapet be 150mm above this, I'd be in the ballpark of 275mm total height, 75mm under the window at the worst point. Keep in mind this is ICF, in my original sketch I thought it was sufficient to have made the PIR lap over the EPS inner skin of the ICF.

No I hadn't. I think I can accommodate insulation in the Posi area, but worry about the hybrid roof thing as this will be under the VCL. I agree on the box gutter shape. I'll have a measure up today and see what I think I can do with having fully vertical sides. I'm just trying to get as much PIR as possible over the wall-roof junction as I imagine that's where potential bridging issues can arise?

Crikey, that does sound like a similar situation. We haven't ordered the windows yet, but I'm reluctant to push the sill level up as it'll be my Grand-Daughters bedroom. I wanted her to have a low sill (I already had to raise it from 800mm to 900mm off the floor). If I have to I will, but it's a last resort. Is the Alwitra VSK the gold standard for this type of coating?

Yes, OSB is what most seem to suggest as Plywood can apparently delaminate under a fully adhered membrane. I agree, the way I've drawn it is off, but I'm trying to figure if the general principle works. Mainly in terms of the parapet wall height in relation to the insulation depth.

@Dave Jones With respect Dave, can you ease up on tearing holes in our design. I hate our Architect with a passion, but we're generally very happy with the overall design. I could do without anything else to feel negative about right now.

Here's a rough idea of what I propose. If this could work, it would be the preferable option. Horizontal Parapet wall on the green lines.... Integral gulleys on the thick red lines. Outlet into the denoted hopper. Flat roof falling in the direction of the red arrows... Very roughly this. The scale is off and the measurements are for guidance. We had planned to fit 200mm PIR into the main roof, so I guess we need to do the same in the flat roof area? 120mm meets our declared as-designed SAP, but we want to do much better than that. I've shown the PIR cut at an angle so as to keep the 200mm thickness as far as possible, but oversailing onto the EPS inner skin of the Nudura. Of course I realise I'd have to place firrings under the Plywood for the fall. Keep in mind there is an outer unifying 50mm skin of EPS to go on in addition to that drawn, this will cover the external timbers. What width should the Parapet be? From the centreline of the Nudura outwards it would be roughly 200mm without needing that inward overhang and might allow the PIR to oversail a bit more. We would run the EPDM up the adjoining walls of the two-storey building. If the Parapet can be kept to 250mm maximum as denoted, it would leave 80-100mm underneath the structural opening of the window. Also, depending on what height the Parapet would need to be in relation to the insulation and gutter depth, it might not even need to be as funky as I've drawn it. @ETC - I would be very happy to pay your rates to do a proper detail drawing if you think a version of this/your idea could work. Any good?

That's an awesome help. You wouldn't believe this but the penny dropped for me earlier this evening with a similar solution. What you've done pretty much nails it, but I'll try and draw what I have in my mind and perhaps run that by you? I'm so grateful for you taking the time with the above.

Yeah, had the Zinc guy turn up this morning to see how I'm getting on. He came up with some ideas, but nothing that I can get on and build without better understanding. I had resigned to it being EPDM or similar, but i believe the Parapets need to be 150mm above the flat roof?

The rearmost window is not problematic, it's the front one. I only have 350mm from the top of the Posis in the flat roof section to the sill. My Architect drew a hopper which I like, but the flat roof really needs a parapet wall approach, which there isn't really enough room for. We opted to beef the insulation in the main roof areas up to 200mm, but this makes the problem in the flat roof section worse unless I can get away with less insulation in that area. We discussed constructing a parapet wall that follows the roofline down and gives the illusion of it continuing to meet the adjoining building, but that window is right in the way of that. Sill is already 900mm, didn't really want to push it up much more.

I'm really pee'd off. I've spent weeks working against what seemed to be an unachievable timeline to get our building ready for the Zinc contractor scheduled to arrive on site at the beginning of July. At this point, I've got 95% of it in hand and feel that I can push to meet the timings, save for one detail. The flat roof link/gutter between the 2 halves of the building. My now estranged Architect has left me with an absolute headscratcher to sort out and this is now most probably the one reason I'll miss my the roof deadline and god knows what consequences with the contractor and the hefty deposit we've paid them. I'd gladly try to lay it all our on here, but I think I need an Architect/Technician to help me sort this out. Is there anyone on here that can save my bacon? I have touched on aspects of it on here before, but I need decisive action as the 5% is consuming waaaaay too much of my head when I need to be sorting out the 95%. I'm gutted that this one detail could see weeks of hard work be in vain.

The Zinc contractor has agreed a build up for the 2 roof areas that he is applying Zinc to. This is a third 'flat roof' section that will not be Zinc'd, but is partly implicated in the main roof, so it's hard to tell if its even his problem. I don't think we can do anything but a warm roof with our design, but the rain noise is a bit of a worry. Is there a better material that could be used perhaps under or over the PIR layer to dampen the noise?

For a warm roof?

What's the alternative to PIR for this application? As for the Architect, she sacked herself. She got paid then said she wants no more to do with the project. Getting another to pick up where someone else has left off is hard! Especially now we're in build and against a timeline.

My Architect specified 120mm PIR insulation for our Warm Roof (Standing Seam VM Zinc). I want to beef the insulation levels up to 200mm. I cannot rely on my Architect for support here. I have a small (10sqm roughly) section of flat roof as part of the scheme where I cannot accommodate 200mm so I need a way to achieve an acceptable u-value compared to the 200mm on the rest of the scheme, but in a thinner build-up (the thinner the better). Any suggestions of ways I can do this would be greatly appreciated. Someone suggested 'Superquilt' as the VCL? I'm poor at understanding u-values, so would appreciate some guidance on this.

@Iceverge Would you be kind enough to show me the sort of product you think would be suited to this purpose? You thinking an expanding foam of some sort? Or Roof Sealant? Would I be able to tighten the wall-plate bolts down sufficiently without compressing the sealant beneath them?

Worse yet, having to second guess weirdly drawn details, like this....