Calculate How Many Downspouts Gutters Need

Cost of aluminum gutters and downspouts.

Calculate how many downspouts gutters need. 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. One 3x4 downspout will drain 1200 sq. Large gutters can hold more water and may not need as many spouts.

The downspout and gutter sizing calculator is located on the tools cad and apps page of the smacna website. Keeping gutters in good condition is more important than many people realize. Adding a 2 by 3 rectangular downspout for instance boosts your gutter s capacity by 600 square feet of drainage area. As with gutters a downspout s capacity must match or exceed the expected runoff.

As with gutters a downspout s capacity must match or exceed the expected runoff. Prices range from 6 12 per linear foot for both gutters and downspouts. 2 by 3 inches 600 square feet. Elbows miters end caps gutter outlets gutter wedges gutter offsets coil sheet goods gutter hangers downspout brackets gutter flashings gutter fasteners conductor leader heads aluminum soffit trim gutter decorations downspout guards accessories paint sealant solder polish tile.

Rectangular 2 by 3 inches 600 square feet 3 by 4 inches 1 200. Aluminum is the most popular choice for gutter material because it s lightweight and durable. Of gutters and downspouts you will be spending about 1 500 1 800. Size downspouts to fit the gutter.

Particularly wet climates could require better drainage systems than relatively dry climates rainy. Typically professionally installed aluminum seamless gutters cost 10 12 per linear foot. Gutters come in many sizes. Doubling the number of downspouts halves the required capacity for each.

Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed. Cost of vinyl gutters and downspouts. Heavy rainstorms put a lot more pressure on gutters. Adding a 2 by 3 rectangular downspout for instance boosts your gutter s capacity by 600 square feet of drainage area.

Smaller gutters may need extra downspouts to make up for their low volume. A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour. From time to time rain gutters wear out and must be replaced. In terms of material options most seamless gutters roughly 80 of all installs are made from aluminum.

Use the chart below to figure out how many extra downspouts you need. 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. Not only can runoff from a roof ruin landscaping next to a building it may cause erosion that will damage the foundation.