[compost]

hi, I've made a 2x2 frame for a shed, external dims 2.4m x 4.2m. on a 6x2" frame base
I've been given a load of pallet planks that are 4 - 5" wide, 7' long and 20mm thick and would like to use these for the cladding. I asked another forum and the advise was to use building paper/membrane before the cladding but it doesn't seem very available to the diy bod in uk (forum was americas). Is this overkill for the uk? I want it to be good but I dont have loads of cash to spend on it and its a softwood field cabin not a home. I plan to insulate, line it, add stove,  etc

So, iyho, do you think horizontal pallet planks nailed like feather boarding, fish scales, overlapped by say 30mm would be ok. Does anyone know anything about this magical building wrap stuff? Is there a home made or alternative version?

sorry about mixing my units
thanks

[Creagan]

There are two membrane layers usually used in an insulated/heated building.
On the inside, a pvc vapour barrier is used to prevent moisture from within the building (breathing, cooking, etc) from passing into the insulation layer. The vapour barrier is therefore 'warm' so should not suffer condensation.
On the outside of the insulation layer, you can choose to install a breathable membrane, or alternatively incorporate a cavity. How waterproof do you think your cladding will end up being? If you have doubts about it, a breathable membrane might be a good idea.

What you do NOT want to do is put a pvc barrier on the outside of the insulation. If you do, the warm moisture laden air inside the building will migrate through the insulation, hit the pvc barrier, and condense. Not good!

[AndynJ]

50m x 1m roll of breathable is approx. £30  Outside, under cladding
18m x 2m insulated foil wrap aaprox. £60 Internal