The roof structure is made of rectangular steel tubes for rafters and galvanized trapezoidal sheet for roofing. Fabrication of this type of roof is simple, mostly using screws and bolts.
Insulation and drainage layer is required on top which may be as cheap as mud+straw+cowdung and/or clay tiles.
It is also possible to cover the roof with a soil layer for a green roof.
The rates of the roofing sheets varies according to the types and quality that you prefer… for poultry form I suggest to choose pre-coated roofing sheets or just check out this link that may help u malurtubes.com/