Attentions in space frame roofing design

With the rapid development of the world’s industry, the space frame roof structure is widely used in industrial buildings due to its light weight, good seismic performance, fast construction progress, large span, large space under the roof among other advantages. However, due to design reasons, problems will erupt in  subsequent use, so the design should pay attention to the following points:

1.Anti-seepage: Prevent rainwater from seeping into the roof panel from outside. Rainwater enters the metal roof mainly through seams or joints. To achieve the anti-seepage function, it is necessary to use concealed fixation after using the sealing washer at the screw mouth, and use sealant or welding treatment at the lap joint of the plate. It isbetter to use long board to eliminate lap-joint in all kinds of joint parts as well as abdominal distension so as to strict waterproof treatment.

2.Fire prevention: metal roofing materials will not burn in case of fire, and the flame will not penetrate the metal roofing plate.

3.Wind resistance: resist the maximum local wind pressure, and the metal roof plate will not be pulled off by negative wind pressure. Wind resistance is related to the binding force of metal roof plate and fixed support and the density of fixed support.

4.Sound insulation: prevents sound from being transmitted from outside to inside or from inside to outside .In the metal roof layer filled with sound insulation material (usually served as a thermal insulation cotton), sound insulation effect in the metal roof layer on both sides of the sound intensitywithdifferent db.The sound insulation effect is related to the density and thickness of the material. Attention should be paid to the sound insulation materials on different frequencies of the sound barrier effect.

5.Ventilation: indoor and outdoor air exchange. Air vents are provided on the metal roof.

6.Moisture proof: to prevent the condensation of water vapor in and between the metal roof bottom layer, and drain the water vapor. The solution is to fill the metal roof layer with thermal insulation cotton, put waterproof film on the metal roof bottom board, and place ventilated joints.

7.Load bearing: bearing construction load, rain, dust, snow pressure, maintenance load. The bearing capacity of the metal roof plate is related to the section characteristics of the plate shape, the strength thickness of the material, the way of force transmission and the spacing of the purlin (secondary purlin).

8.Anti-thunder: lead the lightning to the ground and prevent it from penetrating the metal roof and entering the room.

9.Insulation: to prevent heat transfer on both sides of the metal roof, so the indoor temperature is stable. The thermal insulation function is achieved by filling thermal insulation materials (commonly used glass wool and rock wool) under the metal roof board. Insulation performance is determined by the following factors: insulation cotton raw materials, density, thickness, the humidity of the insulation cotton, the connection mode between the metal roof board and the lower structure (to prevent “cold bridge” phenomenon), and the repeated ability of metal roofing to heat radiation.

10.Daylighting: improve indoor lighting through skylights during the day to save energy. In the specific position of metal roof layout lighting board or daylighting glass, should consider the service life of the skylight and metal roof board coordination, so as to achieve a good waterproof treatment in the skylight and metal roof board connection.

11.Aesthetics: metal roof appearance should have good texture, and pleasant color.

12.Control thermal expansion and cold contraction: control the contraction displacement and direction of metal roof panel.To ensure that metal roofing plate in the temperature difference between regions, will not be due to thermal expansion and contraction of stress and damage.