Flat Roof Gutter Falls

Calculate the gutter slope by dividing the length of the gutter needed by 10.

Flat roof gutter falls.

Flat roof drainage. 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. 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. Rainfall onto flat roofs needs to be correctly managed to protect the structure against ingress of water.

As an read more. For a flat roof to function correctly and to ensure the durability of its waterproof layers it is essential to prevent the accumulation of ponding water and ensure that rainwater run off falls are at the correct angle of slope. The minimal slope needed for proper gutter drainage is 1 25 cm 1 4 inch for every 3 metres 10 feet of gutter. The proper design of falls in a flat roof is an essential consideration in the overall drainage of the roof.

To be effective it is essential to clear surface water as rapidly as possible from the flat roof to avoid ponding or stagnation. 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 rounded up is 2 5 cm 1 inch. Sika limited strongly recommends that in accordance with bs 6229 2018 flat roofs with continuously supported flexible waterproof coverings code of practice and the spra code of practice a minimum 1 80 finished fall is recommended to both the general area of the roof and to any formed internal gutters. Visit this page to know more.

Falls create flow paths to direct the drainage of rain water away from the roof to suitable discharge points. The recommended minimum fall for a flat roof is 1 80 0 72. However the layers used to create these falls often impose an unnecessary additional load and bring no technical advantage.