Sean foley

There’s a decent fall on the roof , could condensation forming under the metal sheets be the issue as I use a electric heater inside the garden room ,

My garden roof roof is leaking , the roof consists of plywood sheets over the joists, the roofing felt over the plywood , then the galvanised metal sheets are fixed , I’ve been up on the roof and can’t figure out how water is getting trough, I was thinking it might be condensation under the metal sheets but it only leaks in heavy rainfalls,

Could I just staple the dpc directly onto the osb ? And have it in tight so no catch tray is formed , I will also have cladding around the sides so it won’t be exposed , should be fine then

Would it be necessary to use doc or will I be fine with out it , it’s osb3 it says it’s weather resistant

I am putting osb on the underside of a garden shed/room I am building to hold the insulation in place , it will be fixed to the underside of the floor joists , the osb3 is 11mm thick and I am wondering will it crush under the weight of the shed ? It will be in direct contact with concrete blocks which are the foundations

I am building a timber framed garden room , It will be suspended on blocks and I will use rock wool insulation between the floor joists, I was wondering what should I have on the underside of the floor to keep the Rockwool in place and rodent free, I was thinking of just using an airtight membrane or should I use sheeting ? , thanks