How Much Drop Should A Rain Gutter Have

All guttering must slope toward the nearest downspout.

How much drop should a rain gutter have. Doubling the number of downspouts halves the required capacity for each. A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour. As a general rule gutter slope is set at 1 4 inch per 10 feet of guttering. This means the downspout end of the gutter should be set 3 4 of an inch lower than the other end.

For rainy climates where gutters will handle a larger amount of water for long periods they should have a maximum distance of 18 inches apart between them. So if you have a 25 foot section of guttering you should set the downspout end of the gutter 5 8 of an inch lower 1 4 x 2 5 5 8 than the other end. Or you can slope the gutters down from each end toward a single downspout placed in the middle of the run. 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.

If you live in a warm place with sporadic rain you can hang gutter hangers close to the middle of the gutter with a spacing of no more than 36 inches or three feet apart from the center. To ensure that gutters drain properly make certain they slope inch for every 10 feet toward a downspout. If the pitch is too gentle water will just fill up in the gutters until it overflows and a too sharp pitch isn t aesthetically pleasing. Most contractors tend to set the slop at one quarter inch per ten feet of guttering.

Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed. Gutters should slope an inch or two for every 40 feet. For example if you have 30 feet of guttering the calculation is 1 4 x 3 0 75 i e. Size downspouts to fit the gutter.

Calculate the gutter slope by dividing the length of the gutter needed by 10. This brings up another important rule to keep in mind. Gutters need to be pitched at a 5 degree angle. For example for every 10 feet of gutter they need to drop 1 2 inch from the high end to the downspout.

For gutter runs longer than 40 feet it s best to pitch the gutter down from the middle to a downspout at each end.