Downpipes are used to efficiently drain water from the roof surface to the storm sewer or to a soakaway. They are characterized by a simple, solid construction. Do you want to create an efficient and durable gutter system for draining rainwater? Not sure what shape, material and size of downpipe will be right for your design needs? Read the guide prepared by Onninen experts.
Check the downpipes at the Onninen wholesaler
What material should the downpipe be made of?
A downpipe is an element of the rainwater drainage system from building roofs. Thanks to the use of gutters and downpipes, foundations, walls and garden are better protected from flooding, which allows you to avoid many costly damages and problems. Various materials are used to produce gutters and downpipes. Plastic models made of polyvinyl chloride (PVC) are especially popular.
This material is extremely durable and strong. PVC downpipes are lightweight, inexpensive and highly resistant to mechanical damage and difficult weather conditions. They do not corrode or discolour due to UV radiation. They are an aesthetic complement to the facade for a long time. There are various colour variants to choose from.
Gutters and downpipes made of powder-coated aluminum, steel - coated steel sheet, and copper are also available on the market.
How to choose the diameter of the downpipe?
One of the factors that determines the choice of a given gutter system is the size of the roof. In order to correctly select the size of the gutters and the diameter of the downpipe, you should consider:
- effective roof area - i.e. the area that requires drainage,
- rainfall intensity in a given location.
As the slope of the roof increases, the effective roof area decreases. This value can be calculated using a special formula:
EPD = (H/2 + W) x L
To perform the calculations, you need to know/measure the height of the roof, the distance from the corner to the ridge horizontally, and the length of the roof slope. The diameter of the downpipe determines its capacity, i.e. the surface from which the water will be drained. It should be remembered that using a gutter with a larger diameter requires changing the downpipe to a larger diameter version. Otherwise, the water will not be drained fully effectively.
Manufacturers often provide tables that facilitate the selection of downpipes, but they are usually not universal, but dedicated to specific systems. For example, it is assumed that smaller roofs, with an area of up to 50 m2, require the use of downpipes with a diameter of approx. 80 mm and a correspondingly larger gutter - approx. 100 mm. In the case of a large roof, with an area of more than 100 m2, the downpipes should not be smaller than 110 mm in diameter, and the gutter should not be smaller than 150 mm.
Both the diameters, as well as the number and arrangement of downpipes and gutters on roofs, are best planned together with a professional, e.g. an architect who prepares a drainage project. The specialist will make the necessary calculations and take into account the specifics of the building, in particular the layout of windows and balconies.
Check the downpipes at the Onninen wholesaler
Choosing the shape of the downpipe
The choices are:
- round downpipes (the most popular semicircular gutters fit them),
- square downpipes,
- rectangular downpipes.
The shape of the gutter and downpipe is not only important for aesthetics. It can significantly affect the life and efficiency of the entire gutter system. The downpipe must be matched to the gutter in terms of cross-section. The cross-section of the downpipe should be equal to 3/4 of the gutter cross-section. Specialists sometimes recommend that downpipe inlets be conical.
It is worth remembering that the semicircular structure of the downpipe makes it easy for various types of dirt to get into it and accumulate in it, e.g. mud, sand, leaves, fruit, branches, feathers and animal hair, etc. They can lead to a significant reduction in throughput and, consequently, damage to the material. Therefore, it is necessary to ensure regular cleaning of the gutter system, especially in the autumn-winter season, when the flowing water tends to freeze.
It is best to consult a professional when selecting downpipes and all other elements of the gutter system. When ordering a gutter system from the Onninen wholesaler, you can count on reliable advice on the optimal diameter, shape and number of downpipes.
Downpipes at the Onninen wholesaler
The Onninen online plumbing wholesaler offers a wide range of plastic gutters and downpipes and accessories necessary for the correct installation of the pipe system in various types of buildings. You can order from us, among others, gutter and downpipe connectors, handles and screws, downpipes, corners, bottoms, elbows, gutter reductions and tees, clamps, cleaners and inspections and many other products. Our assortment includes solutions from the most valued manufacturers of plastic installation systems, such as Kaczmarek and Wavin . The customer is sure that the downpipe he receives is a product of excellent quality, covered by a long-term warranty, resistant to damage and discoloration, lightweight and easy to install.
Still not sure which downpipe will ensure efficient water drainage from your roof? Are you having trouble calculating the effective surface area or selecting the shape or diameter of downpipes and gutters? Contact us! Onninen experts are here to help – both when selecting a complete rainwater management system and when purchasing individual products. Are you an installer or do you sell plastic gutters? We will be happy to cooperate! Special conditions and unique benefits await professionals.