With building design being so restrictive on space these days this is the area where designers must think about how the roofing contractor will make the box gutter comply.
Box gutter sump design.
Typically a box gutter is trapped between two roofs that feed rainwater into it.
Refer to hints for box gutter design marking and cutting the sump spigot mark cut sump hole dress the cut out to neatly fit to the sump decide on the position of the spigot mark and cut the hole.
Establish the sump location this should be the lowest point in the box gutter.
Overflow box gutters must have independent overflow provision discharging to the atmosphere.
A wider overflow needs less depth of overflow hence the box gutter depth will also be reduced.
Or c a sump with a high capacity overflow device.
To do this we need 3 things what is the biggest storm we should design for.
The box gutter depth and the sump length are influenced by the size of the overflow.
A a rainhead b a sump with a side overflow device.
Rainheads are an essential design element for buildings where internal box or trough gutters are used.
However a wider overflow may increase the length of the sump.
A rainhead or sump is a container located between the gutter and downpipe that aids the flow of water away from the roof.
Outlets box gutter outlets must discharge through either a rainhead or sump.
Design a box gutter to an internal sump with a side overflow.
If draining to a sump with a side overflow somewhere along the box gutter use this calculator.
Box gutter design to as 3500 3 2015.
Making the box gutter wider will also reduce the box gutter depth.
A good box gutter design will have falls along its length together with sumps to collect water before it is fed into large downpipes.
Each box gutter run must discharge independently to ether a sump or directly out of the building without changing the size of the gutter or changing direction.
Support the entire weight of the gutter and sumps when full of water as well as a trafficable load at any point in the gutter and sumps.
Box gutter procedure on roof of new 2 story house with flat roof top.
To avoid problems plumbers need to calculate the hydraulic capacity of a box gutter and when designing overflow devices consider whether the discharge of the box gutter is to.
Method used the method used is based on the flow chart fig 3 1 as nzs 3500 3 2003 downpipe and sump depth from fig i4 with minimum sump depth 150mm.
Find the design rainfall.
Design a box gutter to an internal sump with a vertical overflow.