The standard roof assembly for our houses(from top to bottom) is as follows:
Roof decking material (roof tiles, corrugated sheathing, thatch, or wooden shingles)
Battens
Rainproofing (hessian asphalt felt, 2 layers of aluminum foil or any other type)
Plywood with a certain thickness
Upper layer furring strips layer (proper thickness is not disclosed here) (*)
Second layer furring strips layer (proper thickness not to be disclosed here) (*)
A layer of a radiant aluminum foil barrier (*)
Plywood with a certain thickness (*)
Ceiling material
Purlins
Rafters
Truss system
(*) The furring strips system will only be installed upon approval of the client. The thickness of the furring strips is crucial and needs to be properly calculated to obtain the optimum air gap and is based on the thermal index (R-value) related to the outside temperature and inside temperature.