Cormac Foley

thanks for the responses guys. In relation to going with additional insulation, do you see any issues with adding additional insulation under the lower OSB deck and above the ceiling/potential VCL layer, so that I would have a sandwich of insulation-OSB-breather membrane-insulation, like I have shown in (insulation shown in orange but not annotated!) in the second image in my last post?

I was considering 2 options: A: run the vapour barrier along the underneath of the joist, up the side of the joist, across the underside of the OSB, down the side of the next joist, under the joist etc. Then stick it to the block wall. I could notch the joists where required in advance for electrics. Then use a butyl tape on the underneath of the joists when installing the plasterboard. B: add further insulation between the joists and underneath the OSB. Then install the VCL under the joists, up a bit of the sides of the joists to leave room for spotlights and services, across the underneath of the insulation, down the side of the next joist, etc. Again using butyl tape on the underneath of the joists when slabbing and sticking the VCL to the walls.

Hi all, I'm having a 4m x 5m garden office built at the moment (cavity wall construction). My builder hasn't constructed my warm roof as per the detail I provided him (LABCwarranty.co.uk warm ventilated roof detail). He hasn't completed the construction of the roof yet, is there any way of fixing it without having to strip off battens, insulation and the breather membrane he's put in the wrong place? What he has done so far is (from underneath up): OSB3 deck. Breather membrane. Foil backed 100mm rigid insulation (joints are not taped). 1st layer of battens fixed through insulation into rafters. There's 225mm x 50mm rafters underneath the OSB3 deck, could the VCL be installed here although I'll have spotlights and electrics running in this void. The finish will be an EPDM membrane on top of the higher OSB3 layer.

Would anyone have any advice on whether or not a SIP roof (flat roof) needs to be vented and if so, would you have a detail for it?

Think I've finalised the detail for the base, is there anything I'm forgetting or getting wrong? Not 100% on the cladding extending down over the insulation and concrete board The air vapour barrier is shown in pink

Thanks, definitely overthinking it!!!

Back again, how wide would I want to make the boot of a raft foundation and would I be better off having an insulation break between the slab and the boot effectively having a ring beam under the SIP panel? I've seen this detail by Viking House and also Kore.

Thanks for the detail. A few questions: Just wondering if the raft foundation would be considerably more expensive than a strip foundation. What type of insulation would you put under the raft, XPS? What depth of insulation? What strength concrete in the raft? Fibre reinforcement or mesh? Is that a perforated drain in clean stone on the outside of the foundation?

Would the PIR board in an EWI system be used at plinth level?

Thanks Iceverge, would you have a detail for this or could you point me in the right direction. Would it be a lot more expensive to do a raft/insulated slab?

PIR insulation and protection board. Haven't decided yet on whether to use a cement board or to put an EWI render finish on the PIR.

Thanks for the quick response Cheekymonkey. Yeah, the 100mm blinding is a typo, should be 50mm. I was just running the DPM out over the block to act as the DPC. Just worried about the soleplate getting damp and having condensation issues (read a few comments about this issue) Do you think if I kept the DPM as shown in green in my sketch and then joined another piece of the DPM to bring it up the internal face of the SIP that would help?

Hi all, I'm hoping to get some advice on SIP panel foundation details. I'm going to put in a 25m2 garden office and want to have a solid floor so I'm going with a strip foundation. The last block under the sole plate will be a thermal block, this is where I'll also be running my DPM/Radon Barrier. I'll be bolting the soleplate through the block and the DPM, does this not defeat the purpose of the DPM under the soleplate? Is there any way to avoid this? Is there anything else I should or shouldn't be doing with the detail? (I've borrowed the initial design from another user, sorry, can't remember the name)