Gutter Downspout Requirements

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.

Gutter downspout requirements.

Come visit our selection of quality products. Use needlenosed pliers to slightly crimp the elbow to fit into the downspout as shown. Plumbing codes typically use the vertically projected roof. Are sized in relation to rainfall on this basis.

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. As with gutters a downspout s capacity must match or exceed the expected runoff. From chart 1 2 it is determined that a 9 5 in 241 mm half round gutter should be used.

Use the chart below to figure out how many extra downspouts you need. Mm hr rainfall that varies with diameter for example 3. Downspout empties onto the roof. Doubling the number of downspouts halves the required capacity for each.

Welcome to gutter supply your online reference for gutters gutter machines gutter guards and accessories. I have seen several downspouts dented or bent due to mechanical damage. A high slope moves water more quickly and if gutters have trouble dealing with a lot of water in a short. Allow 1 square inch of downspout cross section for every 100 square feet of roof area.

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. The more roof surface above the gutters the more rainwater will be caught and funneled down into those. Adding a 2 by 3 rectangular downspout for instance boosts your gutter s capacity by 600 square feet of drainage area.

Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed. Quite often you will see downspouts that are short and discharge onto the roof which is. Lots of times you will find that downspouts are missing from the gutter system. Screw a downspout elbow to the outlet tube protruding down from the gutter.

Area for drainage design and they often use a square foot. Size downspouts to fit the gutter. Place downspouts at least 20 feet apart but no more than 50 feet apart. Secure the downspout outlet to the gutter with four pop rivets or screws.

For example if you have 30 feet of guttering the calculation is 1 4 x 3 0 75 i e. Wood rot behind gutters. Allowance per square inch of downspout for 1 in hr 25. The number of downspouts will depend on the cross section dimension of the downspout material.

Gutters come in many sizes.