WannabeBob

Thanks @IanR, that web stiffeners do seem consistent with the MI. I don't see any truss clips in your images - how have you fixed them to the top plate? Just nails?

That looks like a good way to halve the number of cuts @Chanmenie; I think we might use this thanks!

You mean something like this? (Sorry about my terrible drawing)

It’s actual height. D35 is for the lean to roof on the right. The insulation is at the rafter as there will be mvhr and pipes run above the false ceiling. Wouldn’t a truss still need to be supported where it meets the wall? The main roof spans a rectangle about 11 by 12m, and has rooms in it. I didn’t think a trussed roof would span that distance especially with maximising the room above?

That could be a good way to do it too. What connector did you use to fix the rafter to the plate @JohnMo?

yes i think i’ll get them to fix that detail even if it does need to eventually go through the contractor.

I’m might end up doing much of it myself too. I reckon there’s going to be almost 100 birdsmouth to cut. Yes it’s pretty much just to support the rafters. The alternative was to rip the ICF off to fix to concrete and we felt like that had more chances of creating a thermal bridge if not done correctly. It’ll be hidden above a false ceiling, so wont be visible once completed.

Thanks @JohnMo So building regs wont have an issue with this? And once we get building regs approval, we’d approach a carpenter and joist manufacturer to liaise with our SE to get this all to work?

Hi all, Our architect have specified a couple of roofs using I-joist rafters, and our SE have the following details on how this connects to the wall plate. I've a bit of concern about the bird mouth, as the diagrams seem to indicate the bottom flange terminating before the plate, and so isn't bearing any load. At least a couple of the I-joist MIs I've seen specifically say that the bottom flage/cord should not be cut short, for example: https://www.jamesjones.co.uk/assets/downloads/subdir/Technical manual 5th edition.pdf Before I send off an email to the SE, I thought I'd check with the BH experts if my concerns are justified, or the SE details are actually OK and I'm just getting my panties in a twist for no reason. Our SE's details below:

Thanks! Yeah I’m going to be doing a whole lot more reading and researching, and maybe I can then convince myself I’m competent 🫡

With the CDM/HSE aspect, I was just going to stage it such that it was clear who was in control of that phase, i.e. ground works and foundation by the ground works crew, trying not to overlap trades etc. But the BRPC roles require explicit handing over from previous to next appointment, and the new BRPC needs to review the previous stages - not something an electrician would care for?!

Yeah, it sounds like as a self builder unless you’re in the industry, you’ve done it before, or have dedicated enough research or training to assume competency, you’re far more limited in options. My initial plan of hiring individual trades and doing some non critical bits myself are quickly evaporating.

Yeah the question is about Building Regs PC, which is distinct from the CDM role of the same name. CDM PC is mostly concerned about the safety while the works are being carried out. BRPC is related to compliance to Building Regulations. There some overlap, but the BSA makes it clear that they are distinct. So for example if a fire were to happen (potentially years after the build was completed) and spread, and an investigation turns up that inadequate fire breaks were built, the BRPC would be brought into scrutiny. Edit: to be clear i’m not suggesting skirting around the competency requirement if unjustified. But all the advice so far about “taking on the role yourself” seems to be addressing the CDM role. And I’m also concerned about smaller trades refusing to take on the role of BRPC if you’re doing in stages and letting that contractor be the PC, as is another common advice regarding CDM. So it looks to me that if you’re self building and not in the industry, realistically you need a main builder.

I guess i’m slightly hung up on the “competence” requirement for the Principal Contractor role. Can I as a self builder who’s not in the building industry be deemed competent?

I’ve just encountered the same issue when our architects were preparing to submit to building regs, as apparently we need to appoint a Building Regulations Principal Designer and Building Regulations Principal Contractor under Part 2A of the Building Regulations. These roles being distinct from the PD/PC roles defined in CDM. They’ve agreed to be the Principal Designer but we need a Principal Contractor(s) How are people handling this if intending to contract trades individually? From the wording of the Building Regulations, each time the client appoints a new BRPC, they need to notify building regs of the change in appointment. Does this mean that when I hire an electrician, they’d have to be appointed as the new BRPC and they would have to notify building regs that they are now the BRPC? Building regs also says that where a new BRPC is appointed, they must review the arrangements made by the previous BRPC. This seems a bit onerous for say a sparky to review something a previous builder might have done, and I can imagine most smaller trades refusing to do this. Has anybody encountered this in practice, and how have people handled arranging individual trades under the new building regulations?