18. Metals A metal is a chemical element that is a good conductor of both electricity and heat. -Steel: is an alloy consisting mostly of iron, with a carbon content. We used it for the construction of beams, columns and roof trusses. -Aluminum: It is a silvery white and ductile element. It's used used as a profile for door frames, windows, railings or fences. -Copper: It is a ductile metal with very high thermal and electrical conductivity. It's used in water, gas and heating facilities.
19. Woods Wood is an organic material, a natural composite of cellulose fibers (which are strong in tension) embedded in a matrix of lignin which resists compression.Is a common material in roofing, doors, windows and wall covering and flooring