Gutter Downspout Requirements

Mm hr rainfall that varies with diameter for example 3.

Gutter downspout requirements. The number of downspouts will depend on the cross section dimension of the downspout material. A high slope moves water more quickly and if gutters have trouble dealing with a lot of water in a short. Doubling the number of downspouts halves the required capacity for each. Allow 1 square inch of downspout cross section for every 100 square feet of roof area.

Plumbing codes typically use the vertically projected roof. This means the downspout end of the gutter should be set 3 4 of an inch lower than the other end. Lots of times you will find that downspouts are missing from the gutter system. Come visit our selection of quality products.

Area for drainage design and they often use a square foot. Divide 1600 sq ft 149 sq m by 160 sq ft sq in 2 3 sq m 100 sq mm to determine that each downspout should have a minimum area of 10 sq in 6470 sq mm. Are sized in relation to rainfall on this basis. Use needlenosed pliers to slightly crimp the elbow to fit into the downspout as shown.

Wood rot behind gutters. Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed. Place downspouts at least 20 feet apart but no more than 50 feet apart. The more roof surface above the gutters the more rainwater will be caught and funneled down into those.

From chart 1 2 it is determined that a 9 5 in 241 mm half round gutter should be used. Gutters come in many sizes. Hold another elbow against the house and cut a piece of downspout to fit between the two elbows. Downspout empties onto the roof.

Allowance per square inch of downspout for 1 in hr 25. Screw a downspout elbow to the outlet tube protruding down from the gutter. As with gutters a downspout s capacity must match or exceed the expected runoff. I have seen several downspouts dented or bent due to mechanical damage.

Gutters and downspouts need to be sized to accommodate anticipated water loads. Secure the downspout outlet to the gutter with four pop rivets or screws. As a general rule gutter slope is set at 1 4 inch per 10 feet of guttering. From table 1 3 it is found that a4 in 102 mm downspout is required.

For example if you have 30 feet of guttering the calculation is 1 4 x 3 0 75 i e. Welcome to gutter supply your online reference for gutters gutter machines gutter guards and accessories. Adding a 2 by 3 rectangular downspout for instance boosts your gutter s capacity by 600 square feet of drainage area. A damaged section of gutter.

A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour.