# Diameter of the gutter - so choose correctly

Depending on the size of the roof and the shape of the gutter, the appropriate size must be calculated so that the water is reliably kept away from the facade. There are some little basic rules to find the right diameter.

### Measure the size of the roof

Based on the size of the roof you can find the right diameter for the gutter. If the roof size is just at the border between two sizes in the following list, you should definitely choose the next larger gutter.

If you install two downpipes and drain the water, for example, at both ends, you only need to consider half of the roof area in the calculation.

#### Roof sizes for semicircular gutter

• up to 25 square meters roof area 70 millimeters in diameter
• up to 50 square meters roof area 100 millimeters in diameter
• up to 100 square meters of roof area 125 millimeters in diameter
• up to 160 square meters of roof area 150 millimeters in diameter

#### Calculate size of box-shaped gutter

The ten-centimeter wide box-shaped gutter does not exist in every building materials market. Either you take the next larger gutter, or you use another sequence. So all the water can be absorbed.

• up to 25 square meters roof area 70 millimeters in diameter
• up to 50 square meters roof area 85 millimeters in diameter
• up to 100 square meters of roof area 100 millimeters in diameter
• up to 160 square meters roof area 120 millimeters in diameter

### Corresponding downpipes for the gutters

• up to 25 square meters of roof area 60 millimeters in diameter
• up to 50 square meters of roof area 80 millimeters in diameter
• up to 100 square meters of roof area 100 millimeters in diameter
• up to 160 square meters roof area 100/120 mm diameter

Tips & Tricks

As you can see, the larger roof areas require a smaller gutter diameter when using a box-shaped gutter. Therefore, the box-shaped gutter can fit better in certain cases.

Wherever a huge semicircular gutter ruins the look, as in a low house with a large roof area or a so-called Nurdachhaus, a box-shaped gutter should be used.