Your gutters have a high point and a low point.
Minimum gutter fall uk.
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.
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The gutter flow rate chart below compares the specific flow rates for each floplast gutter system.
The minimal slope needed for proper gutter drainage is 1 25 cm 1 4 inch for every 3 metres 10 feet of gutter.
If the length of the gutter is 10 5 metres 35 feet the amount of slope required is 1 25 cm 1 4 inch multiplied by 1 metres 3 5 feet which when.
If the run has two downpipes then the high point should be placed between them.
The difference in position between the two is known as the gutter fall.
The amount of collected water increases until it spills over the sides of the gutter.
Comparing floplast gutter flow rates.
The high point is where the highest gutter bracket is placed and is the furthest from the outlet s.
The gutter slope also called the pitch is the amount the gutter tilts down to let rainwater flow out of it.
If your outlet is situated in the middle of the fascia repeat this process at both ends.
Calculate the gutter slope by dividing the length of the gutter needed by 10.
Position and fix a fascia bracket at this point ensuring that it is higher than the outlet and the fall to the outlet is about 3mm per metre.
Have a minimum depth of 75mm at the high end.
This applies to general roof areas along with any internal gutters.
If gutters slope too severely they don t hold water and water could splash over the sides in heavy rain.
Measure from the outlet to around 100mm from the opposite end of the fascia.
All gutters and downpipes should be accessible for maintenance.
Box gutter outlets must discharge through either a rainhead or sump.
If gutters don t slope water gathers in them.
Have a minimum width of 300mm for commercial installations 200mm for domestic installations.
The numbers on the left hand side of the table show the flow rates when the gutter is fixed level no fall and the figures on the right detail the flow rate when the gutter is fixed to a fall of 1 in 350.
