Croccy

By my simple calculations if I use 140mm Mineral wool 35 between studs. I only need 40mm PIR over the top? (U value of 0.172)?

To answer the last 2 replies (thank you both). If I used a 140mm 35 product between studs. (My merchants, Huws Gray, are limited with what insulatio they can supply. Isover I think? I have a Jewsons account but they are way too expensive now) What would my requirement be to go over the top of the studs. (thickness of PIR). This would be the perfect scenario labour/time wise!

90mm I think.

Frame is up (140mm stud, OSB sheathing, 25mm batten + Cement board cladding). Insulation wise I was going for Knauff frametherm 32 (0.33 W/mK)+ superquilt over, taped & cross battened. Which should give me 0.18. The Knauff insulation is very expensive. But the only blanket insulation that has the thermal conductivity good enough! I think I can get PIR cheaper. 75mm would be the equivalent I think? Are there any details out there to show calculations & alternatives?

Can I put a floor slab (30m sq) down without a 100mm concrete slab? Using more MOT, 250mm? Insulation & Screed on top? I know it can be done this way on refurbs!

I have sent them an Email thank you.

The new timber frame garage/office/utilty... will have a shallow double pitch roof (10-12°). To a central ridge. Span is about 2m, length of ridge is 7m overall but there will be internal walls supporting which could be structural. So maybe 4m max ridge length. What sort of ridge should I go for? Steel so the rafters can sit inside it? Glulam? At that shallow pitch, do I need a collar/gusset? Should I treat it as 2 flat roofs joined together? Covering will be single ply, cold roof.

I know a friendly building control officer. So I may just give him a call & get regs as I build , probably be cheaper in the long run too. Yes, footings on the clay round these parts is normally 1m deep. The slab has gone, a foot thick in places! glad I had a man with machine + breaker. Still been here next spring otherwise!

Rebuilding our pre-fab concrete garage with something a little more habitable (office & utility, for now!). Single storey timber ladder frame, clad in feather edge. under 30m sq. shallow pitch roof with single ply covering. We are on heavy clay subsoil. The old concrete slab is going this weekend. I hope! Undecided on foundation type. And whether to just put a 1m deep strip foundation in, so in the future we could go 2 storeys up? It is not subject to regs, but I would like it to comply to future proof it. I am right in thinking a raft would be more expensive to construct than simple strip foundations? Thank you.

Been a carpenter/builder most of my 56 years. Live in a beautiful village in Rural SE Leicestershire. Most of my work is old property re-furbs. We live in a pre war council house on a big plot with great views. Concrete pre-fab double garage is now gone, the old slab is going this weekend. Seeking guidance...........questions to come.