Gutter Downspout Capacity

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

Gutter downspout capacity.

As with gutters a downspout s capacity must match or exceed the expected runoff. The risk of rain gutter overflow from insufficient drainage capacity. As with gutters a downspout s capacity must match or exceed the expected runoff. These are safe numbers meaning designed to work under the strongest rainfall not the average for.

The capacity of a sloped rectangular gutter may be approximated by using a gutter cross section area not less than that of a semicircular gutter and. Size downspouts to fit the gutter. It is possible to use a mix of gutter sizes a mix of downspout sizes and quantities to accommodate the theoretical gallons per minute draining. Adding a 2 by 3 rectangular downspout for instance boosts your gutter s capacity by 600 square feet of drainage area.

Gutter and downspout water capacity. Water capacity values of a gutter downspout system is calculated using the height head of water a gutter can hold the outlet orifice size of the downspout and the quantity of downspouts used. 2 by 3 inches 600 square feet. 3 by 4 inches 1 200 square.

Use the chart below to figure out how many extra downspouts you need. Downspout sizes must not exceed the bottom width of the gutter. The downspout and gutter sizing calculator is located on the tools cad and apps page of the smacna website. 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.

Rectangular 2 by 3 inches 600 square feet 3 by 4 inches 1 200. The gutter outlet capacity should suit the downspout capacity. How to make sure your gutter is large enough and you have enough downspouts. Doubling the number of downspouts halves the required capacity for each.

Van mark brakes ladder max stabilizer outlet punches gutter mate nail hawg end cap crimpers soldering irons accessories downspout crimpers snips hand seamers hand notchers drill bits chuck drivers gloves folding tools gutter nail driver rivet gun 3 8 awl large grip 12 combination. Design of roof drainage systems roof drainage the roof is one of the most essential parts of a building as it protects occupants contents and interior of the structure from the elements. The downspout size must suit the bottom width of the gutter. A scupper serving a designated roof area ï after the number and location of downspouts have been determined the areas to be drained by each downspout should be figured.

15 m is a practical maximum gutter length to be served by a downspout. Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed. Use the chart below to figure out how many extra downspouts you need. To limit the effects of thermal expansion in gutters 50 ft.