Dave Jones

what is your m2 build budget (excluding the land), this will shape the decisions.

the screed is 35mm out ?

this is not a warm roof.

890 is fine, i wouldnt worry about it.

Warm roof rot lol

Make sure there is ventilation at the eaves and the ridge unobstructed by steels etc you need airflow from bottom to top with nothing in its way. if you have a flat roof can look at mushroom vents.

pretty much all wrong. the vcl is there to stop moist air from inside migrating into the insulation. How you going to do that without lapping it down the walls? you could have a parapet and lap it up that but don’t see many sheds with a parapet. the whole point of a warm roof is ventilation is not required as it’s a sealed sandwich by the vcl from below and the covering above.

I don't believe there is a distance requirement for pumped chamber. There is however for ceptic tanks.

almost but you want the vapour barrier to seal to the inside walls so needs to be underneath the joists. also waste of money top decking, you can buy glass fibre backed insulation that takes the epdm spray.

the issue will be where the dew point ( condensation) forms, for example outside is 0c then inside will be between 0c and whatever the temp is inside which will be higher. so condensation will form inside the building its just a case of where. you want it above the insulation so the air gap takes care off it. problem is you dont have a uniform covering just stuffing it between the joists. vapour barrier will do nothing unless you put a warm roof on which will stop it completely.

underwriters have gone bust CRL went a few years ago leaving the warranty worthless.

dont look on any of the consumer sites chekatrade etc as if they are on there for a reason. Have a drive round and find a build happening locally and have a chat, expect to wait for decent trades. personally id drop that side extension and start again its a total bodge and a real trade wont want to be polishing a turd.

http://www.thewatercalculator.org.uk/

you can staple UFH to EPS no problem at all, just have to use more.

stub cills look good with stone cills as you dont have the double cill effect.

you have a cold roof, this means you need copious ventilation to keep it dry. Much better would be a warm roof.

either is fine. if you dont have to wait for a sewer connection then its easiest before the shell goes up as you have space.

nope. you need an air gap under the osb. vap barrier is pointless in a shed.

separate the lounge and kitchen. nothing worse.

ok its an expensive trussed roof, way you trying to make it a warm woof ?

it boils down to m2 cost. £2000/m2 is council house spec. do the math.

n but doesnt meet regs. credit to your builder for walking away. Hope you paid him a bonus.

you have a trussed roof, whats the point in trying to make it a warm roof ?

what is the GDV of the site when finished ?

this time of year when its cold it will mark for 48hours if walked on. 3 days to be safe. This is sand cement with fibres screed laid to 75mm depth.