I have a "log cabin" build onto raised decking rafters, surrounded by decking boards. Id like to remove a window of the cabin and use this as an entry point to a sort of "extension of the cabin", a diy shed attached if you will.

i'd like to build the side shed out of timber. This means I would be laying on existing decking, which has a strong foundation.

can I build my floor frame directly on to the decking using e.g 4x2s as it is? or not?
what are my issues with that?


I was thinking 4x2 create floor frame - attach this frame in place to decking and through to rafters and sideways on to current "cabin"

How would I insulate this floor?

Am i best off laying ply straight down onto the frame then put kingspan onto the ply and finish with a laminate or such?

or should i fit kingspan boards between the frame leaving 2" gap between the insulation board and the decking base below it?


The same for the walls - whats my best bet here to insulate

Build up my 4x2 frame and then dpm the entire frame, then outside skin e.g. ply with log cladding to finish asthetically.

Inside putting kingspan or wool and then finishing with ply or whatever i choose for my internal finishing?

OR

should I simple build wall frame - ply outside.
Batton inside frame to leave 2" air gap, install vent to circulate air.
install kingspan and finish with ply inside?





When i build the wall frames - i want this shed to be fully insulated.

what are my options?

External wood log cladding
moisture barrier sheeting?
insulation roll/bats
internal wall?

what have i missed?