Used to build wood structures, the load-bearing system consists of wooden poles, wooden huts, wood purlin (carried in two wooden huts or one side gable) commonly known as frame, wood rafters (carried in between two purlin), commonly known as the rafters, wood purlin or wood rafters on the nail cabin panels, on board waterproof (linoleum, tile). At this time the cabin panel is commonly known as "Lookout".
Where the roof is set, the building elements that insulate the top-floor room from the topmost outdoor space can be described as roof panels, including reinforced concrete slabs, color plates, wood lookout, etc.
Now the wood purlin is less used, and steel purlin, reinforced concrete purlin and other applications more and more, steel trusses are sometimes used truss-type steel purlin. No matter what material is used, designers are determined by the economic comparison of the structure and cost.
