If you ve got a simple gable end roof then it s easy you only need to know two figures one for either slope.
Calculate gutter size uk.
6 inch 7 960 square feet.
Determine the rainfall intensity for your location.
Calculate the square footage by getting up there with a tape measure.
To limit the effects of thermal expansion in gutters 50 ft.
British standard bs en 12056 3.
Change the style of gutters to one with a greater capacity.
Calculations are based on level gutter capacity as experimentally determined by the national institute of standards and technology nist.
If a roof s various drainage areas call for different size gutters go for the biggest one k style.
For a typical gutter run up to a maximum of 10m the ratio of gutter lengths is calculated from.
That will show how much water a gutter will have to drain.
Choosing the right size of gutters and downpipes step 1.
Lg 10 133 therefore reduction factor 0 86 d 0 1 gutter capacity x reduction factor 2 84 x 0 86 2 44 l s therefore the proposed system is suitable.
Frequency and positioning of outlets downpipes.
That is how much rain a roof can drain during the most intense rainfall.
5 inch 5 520 square feet.
Divide the inch per hour watershed of the roof by the 5 minute rainfall intensity.
15 m is a practical maximum gutter length to be served by a downspout.
Geographical location and rainfall intensity maps.
Downspout sizes must not exceed the bottom width of the gutter.
Increasing the capacity of your gutter system.
L1 l2 selecting gutter size there is no standard rate of rainfall in the uk so for accurate calculations refer to an approved weather authority to get a site specific rainfall level.
Multiply the drainage area by the roof pitch factor and rainfall intensity to find out the adjusted square footage.
2000 contains maps showing.
The most logical way to choose your gutter size would be according to the area of your roof.
Ask gutter suppliers what size gutters will be needed to handle that amount.
Using the 5280 square feet example from step 6 you will choose a gutter size that can handle at least 5280 square feet.
Design area effective area 5 x 10 x 1 29 64 5m run off 64 5m x 0 022 l s per m 1 42 l s from chart 125 x 100 gutter with 76 ΓΈ downpipe appears suitable but check.
Move the outlet downpipe from the end of the gutter to the middle.
Add a fall to the gutters which we recommend you do anyway.