The finish you see — timber, composite or contemporary board, fixed to battens so it can move and dry.
A gap behind the cladding that lets air circulate and moisture escape, so the structure never sits wet.
A breather membrane that keeps rain out while letting water vapour leave the wall.
The engineered timber frame that carries the roof and takes the fixings for everything else.
Fills the frame in walls, floor and roof. This is what makes the room usable in January and July.
A layer on the warm side that stops moisture from inside the room condensing within the wall.
Plasterboard fixed to the frame — a solid, straight wall ready for skim.
Plastered, painted, floored and lit — the standard of a room inside the house.