Flat roof design guide.
Box gutter fall ratio.
This applies to general roof areas along with any internal gutters.
There is always some confusion as to how the slope affects the overall depth.
Fall gradient x distance.
Calculate the gutter slope by dividing the length of the gutter needed by 10.
For example calculate the fall in a 50 metre section of foul water pipework if the gradient is to be 1 in 80.
Minimum width 300 mm for commercial construction and 200 mm for domestic construction.
A gradient of 1 in 80 is converted to a number instead of.
As a general rule gutter slope is set at 1 4 inch per 10 feet of guttering.
Rainhead overflow or specific box gutter overflow must be at least 30mm below the height of the back of the box gutter.
For example if you have 30 feet of guttering the calculation is 1 4 x 3 0 75 i e.
It may be lined with epdm rubber metal asphalt or roofing felt and may be concealed behind a parapet or the eaves or in a roof valley.
According to bs 6229 bs 8217 flat roofs should be designed with minimum falls of 1 40 to ensure a finished fall of 1 80 can be achieved allowing for any inaccuracies in the construction.
This effectively states that all box gutters must allow for 30mm of freeboard which is from the overflow point eg.
The standard is about inch per 10 feet.
A box gutter internal gutter parallel gutter or trough gutter is a rain gutter on a roof usually rectangular in shape.
Box gutters are essentially placed between parallel surfaces as in a valley between parallel roofs or at the junction of a roof and.
Measure the length of gutter needed.
I fall or slope box gutters to be installed with a minimum uniform fall of 1 in 200 towards the outlet.
Box gutter with rain water head at end of box gutter.
The minimal slope needed for proper gutter drainage is 1 25 cm 1 4 inch for every 3 metres 10 feet of gutter.
Box gutters allowable width slope and length.
This means the downspout end of the gutter should be set 3 4 of an inch lower than the other end.
