Anti seepage: prevent rainwater from seeping into the metal roof panel from the outside. Rainwater mainly enters into the metal roof through lap joints or nodes. To achieve the function of anti-seepage, it is necessary to use the sealing washer at the screw mouth and then use the hidden fixation, and use the sealant or welding treatment at the overlap of the plate. It is better to use the full-length plate to eliminate the overlap, and use the water-proof treatment with tight abdominal expansion at various joints.
Fire prevention: in case of fire, the metal roof materials will not burn and the flame will not penetrate the metal roof panel.
Wind pressure resistance: resist the local maximum wind pressure, and the metal roof panel will not be pulled off by the negative wind pressure. The wind resistance performance is related to the fastening force of metal roof panel and fixed seat, and the density of fixed seat.
Sound insulation: prevent sound from outside to inside or from inside to outside. The metal roof layer is filled with sound insulation materials (usually insulation cotton), and the sound insulation effect is expressed by the difference of sound intensity on both sides of the metal roof layer. The sound insulation effect is related to the density and thickness of the sound insulation material. It should be noted that the sound insulation materials have different blocking effects on the sound of different frequencies.
Ventilation: indoor and outdoor air exchange. Set vent on metal roof.
Dampproof: prevent water vapor condensation in the metal roof bottom layer and metal roof layer, and drain the water vapor in the metal roof layer. The solution is to fill thermal insulation cotton in the metal roof layer, lay waterproof membrane on the metal roof bottom plate, and there are ventilation nodes on the metal roof panel.
Bearing: Bear construction load, rainwater, dust, snow pressure and maintenance load. The bearing capacity of the metal roof slab is related to the section characteristics of the slab type, the strength and thickness of the material, the mode of force transmission, and the spacing of purlins (auxiliary purlins).
Lightning protection: lead lightning to the ground to prevent lightning from breaking through the metal roof and entering the room.
Heat preservation: to prevent heat transfer on both sides of the metal roof, so that the indoor temperature is stable. The thermal insulation function is realized by filling thermal insulation materials (commonly used glass wool and rock wool) under the metal roof panel. The thermal insulation effect is expressed in U value, and the unit is w / m2k. The thermal insulation performance is determined by the following factors: the raw material, density and thickness of the thermal insulation cotton; the humidity of the thermal insulation cotton, the connection mode between the metal roof panel and the lower structure (to prevent the “cold bridge” phenomenon); the repeated ability of the metal roof layer to the heat radiation.
Daylighting: improve indoor lighting by skylight during the day, save energy. When arranging the lighting board or glass at the specific position of the metal roof, the service life of the skylight shall be coordinated with the metal roof panel, and the connection between the skylight and the metal roof panel shall be waterproof.
Beauty: metal roof surface has good texture and pleasant color.
Control thermal expansion and cold contraction: control the contraction displacement and direction of metal roof panel. Ensure that the metal roof panel will not be damaged due to the stress caused by thermal expansion and contraction in the area with large temperature difference.
Anti avalanche: set up a snow barrier on the metal roof of the snowfall area to prevent the sudden sliding of snow.
Anti icicles: prevent rain and snow from forming icicles at cornices.