2. The envelope is a component (including some accessories) that constitutes the building space and resists the adverse effects of the environment. According to the position in the building, the envelope is divided into outer envelope and inner envelope. Exterior protection structure, including external wall, roof, side windows, external doors, etc. , used to resist wind and rain, temperature changes, solar radiation, etc. , and should have heat preservation, heat insulation, sound insulation, waterproof, moisture-proof, fire prevention and durability. Internal enclosure structure, such as partition wall, floor, internal doors and windows, etc. , play the role of separating indoor space, and should have sound insulation, line of sight separation and some special requirements. Envelope usually refers to external walls and roofs.
3. Roof structure refers to a mechanical system composed of roof load-bearing members. Such as roof truss, purlin support and roof panel; Roof beams, roof slabs, etc.