Minimum Gutter Falls

Box gutter outlets must discharge through either a rainhead or sump.

Minimum gutter falls.

If gutters don t slope water gathers in them. Falls and drainage it is a requirement of building regulation part h that adequate provision is made for rainwater to be carried from the roof of the building. Put another bracket about 25mm lower at the downpipe end. The gutter slope also called the pitch is the amount the gutter tilts down to let rainwater flow out of it.

Welted drips should extend to the middle of the rainwater gutter and there should be a minimum of 50mm turndown. Overflow box gutters must have independent overflow provision discharging to the atmosphere. Required gutter slope 1 40 to 1 200 there is always some confusion as to how the slope affects the overall depth. To ensure the rainwater is directed towards the gutters the sides of the roof surface apart from the gutter edge require a minimum of 50mm upstand verge provided using triangular pieces of timber called tilt fillets nailed.

Calculate the gutter slope by dividing the length of the gutter needed by 10. As long as there is a fall and water does not stay in the gutter then all should be fine. The depth shown in the calculations is at the upstream end. Measure the length of gutter needed.

Put a string line between the two and put the remaining brackets up. 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. Maximum allowable length between expansion joints with one end fixed. I fall or slope box gutters to be installed with a minimum uniform fall of 1 in 200 towards the outlet.

The minimal slope needed for proper gutter drainage is 1 25 cm 1 4 inch for every 3 metres 10 feet of gutter. Have a minimum width of 300mm for commercial installations 200mm for domestic installations. Put a gutter bracket on at the high end. The amount of collected water increases until it spills over the sides of the gutter.

Attach the level string to the opposite end of where the gutters will be installed. Have a minimum depth of 75mm at the high end. Layout box gutters must. If gutters slope too severely they don t hold water and water could splash over the sides in heavy rain.