Essential for assessing the effectiveness of drainage channels are therefore their location, size, the opening cross-section of the cover and the channel body as well as the installation situation.
A drainage channel will only be able to develop its full effectiveness in reducing the moisture risk in the area of a door threshold if it extends at least over its entire width and is positioned sufficiently close in front of it. This should usually be the case if it is no more than 5 cm away.
Deposits due to dirt ingress are largely retained by the channel body and can be easily removed through the closed channel bottom without damaging the seal. Regular maintenance should be a matter of course here.
The safe drainage of rainwater as well as suspended matter takes place in terrace drainage via the lateral drainage slots into stub channels leading to the drains, into the free space under slab coverings on stilt bearings/mortar bags or into the drainage layer. The drainage slots should not be smaller than 4 mm, otherwise there is a risk of sintering here. The use of chippings smaller than 4 mm is not critical, because experience shows that only a little chippings penetrates through the drainage slots into the channel due to the wedging. If deposits collect on or in the grating due to an inserted dirt fleece, the entire construction is to be judged as critical.
Perforation of channel bodies on one side of the façade is not advisable, as this is a loosely laid open channel system in which moisture inevitably also settles on the façade side. With perforation of the gutter sides on both sides, the moisture is considered to be pressureless and to dry off quickly.