Find the right system

System sizes are adapted to different types of houses. A size 10 rain gutter is mounted on small buildings such as summer houses and roofing over terraces and conservatories. A size 11 is used for traditional houses and size 12 is mounted on large buildings, such as tenements as well as warehouses and industrial premises. In order to ensure that you have sufficient drainage capacity, you should use the following calculations as your starting point.

First calculate the roof area (drainage area: A X B), and determine the location of the downspout.

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Check the drainage capacity

In the table you can gauge the system’s drainage capacity in relation to the location of the downspout. If the drainage area is greater than the figures in the table, you can choose to install an additional downspout, since that increases drainage capacity. Make sure you plan drainage for all downspouts. 

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The above is calculated on the basis of expected rainfall intensity of 0,0146 l/s/m2. 

The rain gutter sizes in the above examples can be combined with the following variable dimensions of the downspouts:

Is there a need for an expansion spout/expansion piece? 

Plastic will move slightly when the temperature varies. One should therefore in the following cases use an expansion spout and/or an expansion piece: