What are internal drainage and external drainage?

Internal drainage and external drainage mainly refer to the area in the direction of drainage slope of building roof. The drainage leading to the outside of the building is called external drainage, and the drainage leading to the inside of the building is called internal drainage (such as open-air patio). The internal drainage system needs to discharge water from the building in an organized way.

Internal drainage system is often used in multi-span industrial workshops, as well as shell-shaped roofs, serrated roofs and workshops with skylights, where it is difficult to set gutters. High-rise buildings with high building facade requirements, large roof buildings and buildings in cold areas are not allowed to set rainwater risers on the external walls, and internal drainage should also be considered.

External drainage system The external drainage system of the gutter consists of gutter, rain bucket and drainage riser. The gutter is set between the two spans, and the rain bucket is arranged along the outer wall. Rainwater falling on the roof is collected on the roof of the gutter along the grave, flows to both ends of the building (gables and parapets) along the gutter, enters the gutter, and is discharged to the ground or rainwater wells through risers. The drainage system outside the gutter is suitable for multi-span industries with the length not exceeding 100m.

Extended data

Drainage system layout requirements

The layout of the drainage system should be as comprehensive as possible:

1, the drainage ditch should be at the lowest place in the control area, so as to drain water by itself as much as possible.

2. According to the terrain, the drainage area is divided into three sections: high, medium and low, so as to achieve high water and high drainage, low water and low drainage, with self-drainage as the main part and pumping as the supplement.

3. The outlet of the main drainage ditch should be selected in the place where the water level in the discharge area is low and the riverbed is relatively stable.

4, decorate the lower drainage ditch to create good conditions for the superior drainage, the main canal should be arranged in a straight line as far as possible. In addition, the drainage ditch layout should avoid areas with poor soil quality, so as to save the project cost and make the drainage safe and timely.

5. In the drainage area with external water invasion, intercepting ditch or flood control ditch should be set up, so that external surface water and groundwater can be directly introduced into the main drainage ditch or drainage area.

References:

Baidu encyclopedia-internal drainage system

Baidu encyclopedia-building external drainage system