When the main structure of the building has no windowsill wall, the horizontal smoke belt of the glass curtain wall should be located between the upper end of the structural beam and the curtain wall structure. And a non-burning solid skirt wall with a fire resistance limit of no less than 1 hour and a height of no less than 0.8m is installed along the outer edge of the floor slab.

If the horizontal smoke belt is set at the lower end of the main structure, the two glasses of A and B will be damaged in a short time when the building encounters fire. Harmful gases will enter the upper floor of the building through the gap C between the curtain wall and the main structure. Although this design ostensibly meets the curtain wall fire regulations, it fails to meet the building fire requirements.

For the main structure of the building without windowsill wall, the non-burning solid skirt wall with fire resistance limit of not less than 1 hour and height of not less than 0.8m is set along the outer edge of the floor slab, because of the consideration of the coiling flame effect. Because the common building interstory structure is about 0.6m, which is smaller than the coil flame radius (1.2m) of general civil buildings in case of fire. This distance is about 1.4m after adding 0.8m non-burning solid skirt wall, which is larger than the coil flame radius. If not set 0.8m non-burning solid skirt wall. When the building meets fire, two pieces of glass A and B will be damaged in a short time. Harmful gases will escape from the broken B glass into the upper floor of the building.

The above forms are to set the horizontal smoke belt at the upper end of the main structure adjacent to the curtain wall. When a building on one floor catches fire, all the glass curtain walls on the same floor will be destroyed. Considering the coiling flame effect, the adjacent glass will also be damaged, so the horizontal smoke belt can be set on the upper part of the structure to ensure that harmful gases will not be able to sneak into the upper floor of the building in a short time.