Water roof in Apeldoorn © Maarten Reiling

Water roofs


  • Dimensioning: 
    Average buffer height of 60 mm (taking the slope level of the roof into account)
  • Application: 
    Flat roofs
  • Advantage: 
    Can be placed on almost any flat roof
  • Disadvantage: 
    Waterproofing requires additional attention
  • Water: 3
  • Multifunctional space usage: 2
  • Costs: 1
  • Construction costs: 1
  • Maintenance/management: 1


Flat roofs can be designed to buffer a degree of precipitation by situating the drain at a slightly higher level. This needs to be taken into account in the roof’s construction (greater load). This type of water roof is called a water roof for rainwater retention. The water only remains on the roof for a short period of time after rainfall. The rainwater is drained off at a delayed pace using a narrower lower situated opening. The water needs to be drained off to create sufficient storage capacity in time for the next rainfall.

The optimum situation would be for the water management of these roofs to have an electronic interface with the weather forecast and discharge the water before the next rainfall, as this would allow both functions to be combined. Such electronic control systems are already used for green roofs.

Water roof © atelier GROENBLAUW
Water roof © atelier GROENBLAUW