Roof Drainage Design Standard

Typical problems and design.

Roof drainage design standard.

In the design and detailing of a roof drainage system consideration must be given to a range of factors such as. This modular system is one of six variations installed on the roof and covers 800 square feet con sisting of two foot by two foot trays with six inches of mineral soil and over 1 500 sedum plugs. An extensive green roof system installed atop the nyc department of parks and recreation s dpr five borough building on randall s island. Typically a low slope roof is designed with one primary roof drain and one secondary roof drain or overflow scupper drainage outlet at the perimeter of the building per structural bay.

Manual for the design of roof drainage systems a guide to the use of european standard bs en 12056 3 2000 r w p may report sr 620 march 2003 address and registered office. Roof drainage layout and calculations. Roof drainage systems should be designed and detailed by a suitably qualified trade or professional in accordance with the bca and the australian standards. To design a sloped or flat roof drainage system we need to know several things.

Quantity and placement of downpipes. The roof design standards focus on high quality and long term performance. These roof design standards are limited to slope to drain roofs with slopes ranging from per foot to 2 per foot. Hence this is by far the most common roof drainage situation.

For most dwellings you ll find that gutters range in size from approximately 100mm diameter to 150mm diameter assuming gutters with a half round section profile and downpipes range from approximately 60mm diameter to 90mm diameter assuming circular downpipes. This manual provides comprehensive guidance on how roof drainage systems for buildings should be designed using information given in european standard 12056 3 2000 gravity drainage systems inside buildings part 3. Particular reference should be made to the correct sizing of gutter. This manual was produced based on experience and expertise in 40 year roof performance.

The manual is intended to be used in conjunction with bs en 12056 3 and contains separate chapters dealing with the following topics. To size the vertical roof drain for the same parameters 5 000 square feet of room area and 6 per hour of rain consult table 1106 2 figure 3. Rainfall data effective catchment area design flow loads capacity of freely discharging gutters. The maximum rainfall rate anticipated in the area where the building is located the flow in liters per minute per square meter for some x number of minutes.

And the provision of appropriate overflow devices. Hr wallingford ltd howbery park wallingford oxon ox10 8ba.