Principle of rain curtain and waterproof structure design of stone curtain wall

The principle of the rain curtain is a design principle that points out how the penetration of rainwater into this "curtain" will be prevented. In this application of the principle, the main factor is that there is a cavity inside the joint, and the outer surface is The pressure on the inside must be kept equal to the outdoor air pressure at all locations, so that both sides of the outer surface are in an equal pressure state, and the outer surface mentioned therein is the "rain screen." The pressure balance is obtained by intentionally leaving the opening open to allow the cavity and outdoor air to circulate to achieve pressure balance. This effect is formed by the cavity left behind the outer wall. This cavity must be connected to the outside to achieve the above purpose. The gust fluctuation caused by the randomness of the wind also needs to be balanced on both sides of the outer wall.

As we all know, there are three elements for the leakage of the curtain wall:

A. There should be gaps on the curtain wall;

B. There must be water around the gap;

C. It has the effect of allowing water to enter the interior of the curtain wall through the gap.

If one of the three elements is missing, leakage will not occur (if the effects of these three elements are reduced to the minimum, then the leakage can be reduced to the minimum). Water and crevices on the outer wall cannot be eliminated. Only by working hard to eliminate water, the water will not enter the isobaric cavity through the crevices on the outer wall. On the inner wall, the gaps and effects (especially the pressure difference) cannot be eliminated. To achieve no leakage of the inner wall, the water must not reach the inner wall. This is precisely achieved by the effect exerted by the outer wall (rain screen). If water cannot enter the isobaric chamber, there will be no water on the inner wall. If there is no water around the inner wall gap, there will be no leakage on the inner wall, so that no water will seep into the interior of the united curtain wall. The core principle of this design is the equal pressure inside and outside the outer wall (rain screen), so that the rainwater can not enter the equal pressure chamber, and there is no water around the inner wall gap, that is, the inner wall eliminates the factors of water in the three elements to achieve the unitary curtain wall connection The joint system does not leak.In this way, the waterproof structure of the joint of the unit curtain wall should make the outer wall have the ability to prevent a large amount of rainwater from infiltrating, and the small amount of rainwater that penetrates into the isobaric chamber can be discharged immediately, so that the water cannot reach the inner wall, and the water factor in the three elements of leakage is eliminated on the inner wall , So as to prevent rainwater from leaking into the room.

It must also be pointed out that this is just a theoretically stated principle. It is not easy to completely eliminate any of the three elements of leakage in actual engineering, but it does not mean that we are powerless, although the three elements of leakage cannot be completely eliminated. The purpose of any one of the above, but measures can be taken to minimize each of the three elements of leakage. In this way, on the basis of learning foreign experience and summing up the domestic experience, there is a set of more mature technical solutions for the design of the waterproof structure of the unit type curtain wall to the joint, that is, setting the poncho on the outside of the horizontal (vertical) joint, only in two units A small opening is left at the connection point of the component to allow the equal pressure chamber to circulate with the outdoor air to maintain the pressure balance, so that a continuous outer wall (rain screen) is formed from top to bottom and from left to right. The poncho prevents a large amount along the entire length of the joint Rainwater infiltrated inside the curtain wall, only a small amount of rainwater infiltrated at the opening, and the water layer falling along the mullion cavity was collected with a sealing plate (sump) and immediately discharged to the surface of the outdoor panel to drain, and the drainage hole was far away from the joint to reduce Gathering of water around the gap.