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outlets . Not considering these will led to overflow and blockages – none of which are helpful to the owner or the building .
Gutter capacity The flow capacity of a gutter will vary according to the fall of the gutter and the positioning of downpipes and gutter angles . An outlet situated centrally in a length of gutter drains water from the gutter at twice the rate provided by a single end outlet .
Gutter fall . Tests show that the performance of eaves gutters is improved by 20 % at a fall of 1 in 600 . Excessive falls are to be avoided because , apart from the bad appearance , a wide gap between the roof edge and the gutter results in wind driven rainwater missing the gutter .
(* SANS 10400 : L section 4.3.2 – Gutters and downpipes makes it clear that “ the outlet shall be set flush with the concrete or recessed into the timber decking to prevent ponding at the outlet .” The section advises on distances and makes the point that the manufacturer ’ s instructions must be followed .)
Effect of gutter angles . A square gutter angle situated within 2m of an outlet will reduce the drainage capacity of the gutter assembly .
© SA Plumbers ’ Handbook www . plumbingafrica . co . za @ plumbingonline @ plumbingonline @ PlumbingAfricaOnline September 2022 Volume 28 I Number 7