Drainage Channels for Underground Garages

Why should underground garages be drained?

Underground garages located at lower levels are particularly susceptible to rainwater ingress. The risk of flooding can be significantly reduced by installing a roof at the entrance and a skilfully designed slope into the drainage system of the surrounding properties and streets. In multi-storey car parks, not only rainwater but also snow (meltwater) can enter through vehicles. The focus here is on safety. Dripping or trailing water can cause the formation of pools of water and thus pose a risk of slipping. The use of drainage channels not only improves safety, but also protects the building fabric from moisture damage. This helps to extend the service life of the structure

Example: False ceiling in a multi-storey car park with a flat evaporation channel and 2% slope.

What is an evaporation channel?

An evaporation channel collects excess water in the channel, but does not drain it away via a drain. Contact with the ambient air converts the liquid water into a gaseous state. The use of evaporation channels makes sense if only small amounts of water are to be expected, for example from melting, dripping and trailing water that enters the underground garage through vehicles. In multi-storey car parks, a combination is sometimes used in which some channels are connected to drainage channels while others function as evaporation channels. The decision not to connect to drainage channels not only saves costs and space, but also results in less water being discharged.

Example: Ascent and descent of an underground garage with 12.5% (start and end section 5%) and 2% slope to the drainage channel.

Special requirements for ramp drainage

Ramps are ascents and descents that are characterised by a steeper slope (>5%). Due to the steeper slope, the penetrating water reaches higher flow velocities. If the nominal width and the drainage capacity of the drainage channel are too small here, the water may overflow. The appropriate nominal width depends on the specific conditions of the ramps, such as the presence of a roof, and should be considered on an individual basis. Another aspect of ramps is the increased horizontal and shear forces that act on the channel during acceleration and deceleration. In such cases, we recommend monolithic drainage channels such as the HYDROblock, which are specially designed for transverse traffic.