Calculate How Many Downspouts Gutters Need

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Calculate how many downspouts gutters need.

From time to time rain gutters wear out and must be replaced. Smaller gutters may need extra downspouts to make up for their low volume. Doubling the number of downspouts halves the required capacity for each. Adding a 2 by 3 rectangular downspout for instance boosts your gutter s capacity by 600 square feet of drainage area.

Typically professionally installed aluminum seamless gutters cost 10 12 per linear foot. 3 by 4 inches 1 200 square. Gutters come in many sizes. Large gutters can hold more water and may not need as many spouts.

Now architects engineers designers and contractors can easily and accurately size downspouts and gutters according to the specifications in smacna s architectural sheet metal manual 7th edition 2012. Use the chart below to figure out how many extra downspouts you need. Aluminum is the most popular choice for gutter material because it s lightweight and durable. So if you need to install 150 ln ft.

Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed. The downspout and gutter sizing calculator is located on the tools cad and apps page of the smacna website. 2 by 3 inches 600 square feet. As with gutters a downspout s capacity must match or exceed the expected runoff.

On average two hundred feet of gutter and 50 feet of downspout will cost approximately 2250. Particularly wet climates could require better drainage systems than relatively dry climates rainy. Rectangular 2 by 3 inches 600 square feet 3 by 4 inches 1 200. Size downspouts to fit the gutter.

Keeping gutters in good condition is more important than many people realize. 3200 square feet of roof is calculated as 3200 600 5 33 rounding up you would need 6 2x3 downspouts or 3200 square feet of roof is calculated as 3200 1200 2 67 rounding up you would need 3 3x4 downspouts one 2x3 downspout will drain 600 sq. Cost of aluminum gutters and downspouts. A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour.

One 3x4 downspout will drain 1200 sq. Of gutters and downspouts you will be spending about 1 500 1 800. As with gutters a downspout s capacity must match or exceed the expected runoff. Not only can runoff from a roof ruin landscaping next to a building it may cause erosion that will damage the foundation.

In terms of material options most seamless gutters roughly 80 of all installs are made from aluminum. Prices range from 6 12 per linear foot for both gutters and downspouts. Heavy rainstorms put a lot more pressure on gutters.