To design a sloped or flat roof drainage system we need to know several things.
Roof drainage design standard.
The manual is intended to be used in conjunction with bs en 12056 3 and contains separate chapters dealing with the following topics.
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.
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.
These roof design standards are limited to slope to drain roofs with slopes ranging from per foot to 2 per foot.
Minnesota state goal for roofing performance.
An extensive green roof system installed atop the nyc department of parks and recreation s dpr five borough building on randall s island.
In the design and detailing of a roof drainage system consideration must be given to a range of factors such as.
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.
Hr wallingford ltd howbery park wallingford oxon ox10 8ba.
Drainage area a with sub areas 1 thru 7 delineated in the absence of a minimum design factor based on the structural design of the pavement the res ervoir depth should be a minimum of 6 inches above the underdrain or choker layer.
And the provision of appropriate overflow devices.
Roof drainage systems should be designed and detailed by a suitably qualified trade or professional in accordance with the bca and the australian standards.
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.
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.
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.
The roof design standards focus on high quality and long term performance.
Particular reference should be made to the correct sizing of gutter.
Roof drainage layout and calculations.
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.
Hence this is by far the most common roof drainage situation.
According to the chart for 1 8 slope per 12 of pipe for 5 000 square feet of roof area with a 6 per hour of rainfall the required pipe size is 8.
Rainfall data effective catchment area design flow loads capacity of freely discharging gutters.
