On the surface of the glass curtain wall, in order to use the principle of rain curtain for waterproofing, the design makes the pressure Pc of the isobaric chamber equal to or close to the outdoor pressure Po, that is, the wind pressure on both sides of the watertight line is basically equal, eliminating or reducing the effect of wind pressure, so that water does not or rarely enters the isobaric chamber through the dust tight line and the watertight line.

Dust line is a sealing line designed to prevent dust. It is generally realized by overlapping adhesive strips of adjacent units to prevent dust and water.

The watertight line is an important defense line of the unit curtain wall. A small amount of water leakage through the curtain wall surface can cross this line and enter the isobaric chamber of the unit curtain wall. Through reasonable structural design, the water entering the isobaric chamber will be discharged systematically without the ability to continue to enter the room, so as to achieve the purpose of water blocking. Sometimes in order to improve the watertight performance of the glass curtain wall, it is possible to set multiple watertight lines at the same time.

The air tight line is also an important defense line of the unit curtain wall. Because the isobaric cavity between the water tight line and the air tight line is basically communicated with the outdoor space (sometimes, sponges are placed on the connected holes to prevent dust), the water tight line cannot prevent air penetration, because it is the last line of defense to prevent air penetration.

On both sides of the gas-tight line, gaps and functions are also inevitable. To achieve the purpose of non-leakage, water should not be soaked into the gas-tight line and the water factor in the three elements of leakage should be eliminated. Since there is little or no water through the dust tight line and water tight line, coupled with reasonable organizational drainage, there will be no water to the gas-tight line, and no water around the gap of the gas-tight line, leakage will not occur. So that the unit type glass curtain wall has good waterproof ability to insert parts.
The weak link of the waterproof of unit glass curtain wall is the "+" word seam of four units, which is the key to the success of the waterproof of unit curtain wall. At present, the more successful solutions include the horizontal sliding type and the "+" word cross-sealing structure.