Basically, a flat roof is drained through a main drainage system in the underground pipe and an additional emergency drainage system on an area that can be flooded without damage.

Normally, 2 separate drains are required for each low point on the roof: 1 main drain that runs constantly and 1 emergency drain with a damming element that only drains from the underground pipe in the event of the rain of the century or in the event of a backwater.

A main-emergency combination system combines the main and emergency drainage functions in just one drain and still ensures two separate flow paths that do not influence each other.

However, only 1 drain has to be sealed and only 1 opening through the parapet has to be made. Pipe-in-pipe or double-pipe drains are common.

Every flat roof and flat sloping roof can be drained with main emergency combi systems. Especially with small and medium-sized roof areas between 50 and 500m², the advantage over separate systems is most evident.

Example: With a partial area of approx. 150m², at least 2 separate drains and downpipes are normally required, whereby the effort when using a main emergency combi system is halved to 1 system. The visual advantage is an additional argument in modern residential and commercial buildings, as only a visible downpipe is required.

Depending on the size, nature and use of the roof area, there are several main emergency combi systems to choose from.

The innovative pipe-in-pipe complete system LX772 from LORO has been a proven solution for the main emergency combi parapet drainage for years.

According to the patented pipe-in-pipe technology, the pipe for emergency drainage in DN50 is routed “invisibly” within the main drainage in DN100, without the two flows being able to influence each other. The reduction of the cross-section of the DN100 main drainage ensures optimal use of the space with more water and less air and thus also ensures a better self-cleaning effect.

The internal emergency drainage in DN50 is designed as a powerful pressure flow.

Another possibility is the LORO-X DUOFLUX double pipe solutions.

For example in DN70 / 70 for up to 75m² per main emergency combi drain or in DN100 / 100 up to approx. 150m².

Despite the low penetration depth of the double pipe drain of only 52mm in the DN70 version, the left drainage pipe drains 2.2 l / s with a water height of only 35mm on the roof into the underground pipe. As an emergency drainage, the right drainage pipe achieves a drainage rate of 3.4 l / s at a water height of 75mm on the roof as a spout to the outside.

The LORO-X DUOFLUX systems of the series 43 parapet-Direct due to the space-saving construction directly in the parapet upstand, they are particularly suitable for walkable or used roof areas.

The LORO-X pipe-in-pipe principle has proven itself many times in parapet drainage and also offers the vertical drainage decisive advantages.

In this way, the number of roof penetrations from the roof into the building can be reduced, as the emergency drainage is routed through the same roof penetration with a separate flow path.

For special roof drainage tasks - e.g. with modern column drainage from central bus stations (ZOB) - the safety and aesthetics of the roof drainage are optimized.