They determine the roof area slope and rainfall intensity.
Roof downpipe design.
Roof area m gutter flow litres sec roof area m downpipe at centre half round 76mm 0 7 34 0 8 38 112mm 1 8 86 2 6 125 squareflo 3 2 154 3 8 182 125 68mm downpipe 3 8 182 4 6 221 82mm downpipe 4 0 191 4 9 235 regency 4 2 202 4 7 226 highflo 5 4 258 6 0 289 stormflo 110mm 11 1 534 12 4 598 160mm 12 5 601 14 0 673 downpipe at end half.
This is particularly important with 2 storey designs where upper floor walls intersect lower storey roofs and drain water onto the roof increasing the total roof catchment area.
Design of eaves gutters box gutters downpipes to the australian national plumbing code as nzs 3500 3.
They also influence the use of gutters and downspouts roof drains and scuppers.
The process of calculating the required size of gutters and downspouts involves.
Plumbing and drainage part 3.
Particular reference should be made to the correct sizing of gutter.
Builders plumbers and roof plumbers installing roof drainage systems should be fully aware of all the factors for consideration requirements and options available.
For roof slope less than 12 5 degs design as a box gutter.
Free online calculator for the design and sizing of roof eaves gutters and downpipes to the australian plumbing code downpipe and eaves gutter calculator to as nzs 3500 3 2018 stormwater drainage acceptable solutions.
Roof drainage systems should be designed and detailed by a suitably qualified trade or professional in accordance with the bca and the australian standards.
The building type its appearance and location have a direct influence on the design of the roof drainage system.
Design approach for a given roof configuration the first task is to decide on the number and location of downpipes as this will determine the size of the effective roof areas.
Designing the roof as an integral component of the overall building design will ensure roof drainage is not compromised.
Approved document h suggests that to achieve this roofs should be designed with a suitable fall towards either a surface water collection channel or gutter that surface water to vertical rainwater downpipes which in turn connect the discharge to the drainage system.
The bca specifically provides standards for the design and construction of downpipes and gutters and calls up the as nzs 3500 3.
A downpipe is typically vertical and extends to ground level.
And the provision of appropriate overflow devices.
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