Mr Blobby

You'll will have two lintels over each opening, one on the inner leaf, one on the outer leaf, so cavity width is irrelevant.

I'm going round in circles with roof buildup 😫 and decision time is here. We started out with a warm buildup but with spray foam between the rafters (as an airtightness strategy that should be difficult for a main contractor to get wrong) but I was not keen on. I have taken responsibility on site for the aritghtness so the foam will be replaced with an airtight membrane in the loft. The architect then proposed the cold-roof, warm loft buildup above but I've been told by the insulation sales guy that it will present a condensation risk if we put metac between the rafters and then 100mm PIR underneath the rafters. He's not done the condensation anlaysis on this yet though. So, starting afresh, our requirements are: 1. We have no ridge height restriction to limit roof height so insulation on top of rafters is no problem 2. Standing seam aluminium covering 3. Some vaulted ceilings but about 90% ceiling josts and loft space 4. Cut roof supported by 2 purlins What roof buildup can I install to get a low u-value pitched roof without condensation risk? It can't be this difficult, surely 🤨 What about this.... 1. prefa aluminium standing seam 2. seperation layer 3. ply 4. battened +50mm air gap 5. breather membrane 6. PIR 7. Do I need another layer of ply in here between the rafter and the PIR ? 8. 150mm rafter 9. 150 mm Metac or similar between rafters, or does this hybrid roof present a condensation risk? 10. Airtight membrane like intello plus or Isover Vario 11. plasterboard How much PIR can I put on top of the rafters to reduce the overall u-value? Is there a sensible limit? is this done in two layers and taped? Roof construction is starting in about two weeks so I need to decide this now 😬. Please help!

Here's that paint tin. It says the sealer is optional if the beams are in dry concealed conditions. They will be dry at some point, but not during construction.

Energy storage is never going to make a contribution. Well not transmission network attached storage anyway. Current technologies like batteries do frequency regulation and pumped storage is there for short-term reserve. There will remain the need for conventional generation plant, which will almost certainly be gas turbines, into the renewables age for the days the wind doesn't blow. That gas plant will just run less often. Which is good. Alongside the gas units will be more demand side management, as there already is for industrial users who have contracts to stop factories etc at short notice. And more smart meters and flexible tariffs. Electricity demand has actually fallen for much of the last 15 years, mainly due to better regulation of things like LED bulbs and inefficient vacuum cleaners, much of which has been driven by EU regulation. The increase in demand going forward is likely from things like EVs (and domestic batterries) that are charged over night when wind is curtailed hence the forecast increase in wind penetration. And CCS is about as real and viable as the tooth fairy.

They do have a misleading name. But we have all heard of them and that's their goal. I've never been affected by them but then I don't drive in a big English city or watch cricket or snooker much.

This is a common misunderstanding. Just stop oil actually campaign to stop new licenses for gas and oil. They don't actually call for everyone to stop using oil right now, or even to stop extracting oil out of existing wells. They just want us to use less of it over time.

Thanks @Mr Punter My mistake sorry, I meant mineral wool between rafters of course, not above. 🙄 So no ventilation gap is required between breather membrane and mineral wool between rafters. That's good. Our architect seems to be keen on PIR between rafters. Not sure why. We can hit our target u value with 150 mineral wool between rafters and PIR under rafters ok. Detail diagram has airtigtht membrane placed between layers of insulation. I would have thought easier to install the airtight membrane under the insulation. At the purlins the membrane is just taped to either side of the steel I reckon. Under, over, does it matter?

Here you go... Good question. No ridge detail available yet. I assume it is vented. No Dormers No plans to do that. Roof will be covered in standing seam aluminium, so no tiles. Is there anything missing here? Well I hope the SE and architect have figured this out right! AFAICS there are two steel purlins supporting the roof. Otherwise roof is standard 35 degree cut pitched roof with gable ends, not a hipped roof. No dormers.

Sorry if this is answered elsewhere but here goes... Following the warnings on here about warm/hybrid roofs we are going for a cold roof over a warm loft construction. Well I thnk we are, I've not done this before, hence the need for some guidance on here. The proposal from the architect is like this: 1. standing seam 2. standing seam breather 3. ply 4. batten + ventilation gap 5. breather membrane (replacing old roofing felt type) 6. batten + ventilation gap 7. PIR between rafters 8. Airtight membrane 9. PIR under rafters Cut roof hanging off two steel beams AFAICS Architect diagram like this: So my questions are: 1. Cutting PIR between rafters seems like a challenge that will end up with lots of air gaps. What about mineral wool between rafters and PIR below rafters? 2. Builder says we can do mineral wool between rafters, full fill up to the breather membrane. The 50mm gap between breather membrane and PIR is not needed for mineral wool. Is that right? 3. Architect says mineral wool is no good above rafters because cold air will blow through it like a wooly jumper on a windy day. 4. Is this cold roof / warm loft thing a typical design? Any general way to improve this? I like the idea of mineral wool for the sound insulation too. Any advice on buildup here very welcome.

They're probably hoping they will get paid without putting the cills in 😆 ... the irony here is that the cills will in fact be concrete heads that will be covered by aluminium cills from the window manufacturer, so they will be covered up anyway.

Exactly this. I have one window opening that's 3 metres wide. How is that sill going to be lifted without a crane, and how is it possible to slide that sideways into the opening? Its a recipe for a total ballacks I reckon 🧐

Maybe its an Ireland thing then? I prefer the build-in approach I think. I'll see how shocked the brickies are when I mention it on Monday 😬

That's what I thought. Thanks.

So my bricklayers like to crack on with the blockwork and put sills in later. Like this: There will be some heavy 3G windows on the sills so naturally I want them properly bedded in and perfectly horizontal without any risk of moving / twisting. I worry that the mortar bed above and below the sill at each end won't be properly filled if sills are slid in instead of placed down and built up. Should I tell the brickies to build in the sills as they go, or does it not matter?

Lindab airy valves look differnt. @Conor, are the flat plates slightly lower than the ceiling?

This stuff I think. https://www.rawlinspaints.com/home/fire-retardant-paints/steel-intumescent-paint/5227-thermoguard-thermocoat-wi-ultimate.html The tin is in the wheelie bin. I'll go and check when back on site on Tuesday.

One coat. My builder laughed when I asked if it needed a second coat. On the tin it said the sealant was optional. AFAIAA the BCO has never questioned the paint, as long as he can see it. I'd be concerned about that beam being cantilevered too! I can see that's how it looks from the picture above, with a body hiding the detail. This picture shows it better, witht the steel supported, taken from a differnent angle:

Yes, the paint company had the steels plan and calulated the required quantity. No I agree, I think the paint is probably a waste of time but building control like to see it. ..Painting wasn't as bad as I expected. But then after reading all the comments here, I was expecting it to be hellish. 😬 Yes its thick and hard work but my builder actually pitched in to halve the pain. Which was nice of him. And here's the finished beam, with a bit welded on to take it over the middle of the padstone and beautifully painted. 🤗

Holy crap, our flow rates are more than double part F recommendation. Thanks for this, I'd not looked at that document before, just assumed the flow rates from the M and E guys must be about right. Yes, they will be dialled down 👍

Your doors sound good. Which ones do you have? eclisse? Another?

Would you not have to pay capital gains tax here because you could end up owning two houses so subsequently disposing of one is a txable event?

I'd assumed the same cross section as the one installed. I'll ask...

Structural Engineer has got back to me about this RSJ (and some other things hence the delay). He says the bearing is "a bit short". He says it works in calculation at 210mm but if replacing the steel then he advises 250mm bearing to give some additional capacity. He has suggested an alternative to replacing the RSJ may be to weld a piece on at the end. Glad I checked this🧐

Surprised to hear that. Why? Who Says? Architect and builder say so because I'm doing it so it costs them nowt. There is a lot of painting to do though. Builder says do it after the hollow core slabs are in place but before then sounds more logical as @Conor says. Our BCO is allegedly easygoing on this. Any tips on the painting to make my life any easier? What's the sealing coat?

Indeed. I have run this past the SE and waiting for a full answer. There were some other issues on other padstones being installed that are smaller than specification 🧐 so this is part of a wider enquiry. I would have made that steel a bit longer to sit further over the centre of the padstone, but that's just me wanting done as best as possible rather than to min spec to save costs. The irony is, however, that it is probably just as well it isn't 😉 Yes. That's exactly what our SE has asked. Medium density 7N is the answer. So standard blocks. Interestingly enough the only some of the bigger padstone sizes supporting the bigger steels are explicitly specified on the SE drawings. And nothing AFAICS about how much steel should be resting on the padstones. And this padstone is not one that the SE has explicitly sized. The single slab between the two steels should rest on the L-shape at the end on the left. That's the theory anyway. If the slabs are the right size and installed in the right order of course. I have a choice of paint or paint. I'll be doing the painting myself so its nice to hear this is a shitty messy job to look forward to🧐. The funny thing is that (I have since remembered) a gap is needed above that padstone to run some services including MVHR ducts in the ceiling void to the kitchen. So, while I may have made that RSJ longer, its a good thing that it doesn't sit across the whole padstone as I have don't have good alternatives to run the ducts 🤪