Box Gutter Fall Ratio

Box gutters allowable width slope and length.

Box gutter fall ratio.

This applies to general roof areas along with any internal gutters. Required gutter slope 1 40 to 1 200. This effectively states that all box gutters must allow for 30mm of freeboard which is from the overflow point eg. For example calculate the fall in a 50 metre section of foul water pipework if the gradient is to be 1 in 80.

Calculate the gutter slope by dividing the length of the gutter needed by 10. A gradient of 1 in 80 is converted to a number instead of. 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. Flat roof design guide.

Box gutter with rain water head at end of box gutter. Rainhead overflow or specific box gutter overflow must be at least 30mm below the height of the back of the box gutter. Simplified suitable for flattish roofs with little or no vertical faces or steep roofs draining to one side of box gutter only or any roof if you are in a hurry and make the necessary allowances for all catchments. Minimum width 300 mm for commercial construction and 200 mm for domestic construction.

I fall or slope box gutters to be installed with a minimum uniform fall of 1 in 200 towards the outlet. There is always some confusion as to how the slope affects the overall depth. Measure the length of gutter needed. The standard is about inch per 10 feet.

Increasing the pitch increases a gutter s handling capacity but the gutter may look askew over a long run. The minimal slope needed for proper gutter drainage is 1 25 cm 1 4 inch for every 3 metres 10 feet of gutter. As a general rule gutter slope is set at 1 4 inch per 10 feet of guttering. A box gutter internal gutter parallel gutter or trough gutter is a rain gutter on a roof usually rectangular in shape.

For example if you have 30 feet of guttering the calculation is 1 4 x 3 0 75 i e. Fall gradient x distance.