Gutter And Downspout Design Calculations

The gutter and downspout size required is highly dependent on the amount of gutter and the spacing of the downspouts.

Gutter and downspout design calculations.

The following is a list of the minimum required design. Doubling the number of downspouts halves the required capacity for each. Please lower the maximum spacing between downspouts to see this effect. Calculations are based on level gutter capacity as experimentally determined by the national institute of standards and technology nist.

Use the chart below to figure out how many extra downspouts you need. A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour. Featuring durable plastic construction this extension can be buried bent or connected to additional sections. Adding additional downspouts will require less gutter and downspout volume resulting in smaller gutters downspouts.

Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed. Adding a 2 by 3 rectangular downspout for instance boosts your gutter s capacity by 600 square feet of drainage area. 3 by 4 inches 1 200 square. 15 m is a practical maximum gutter length to be served by a downspout.

2 by 3 inches 600 square feet. Size downspouts to fit the gutter. Remember to save this spreadsheet to your own computer. 2 4 gutter and downspout sizing and location calculations both metric and english units.

Smacna s new downspout and gutter sizing calculator enables the user to manually enter the design area of the roof or use the design area wizard for the calculation. Once an architect has. 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.

Leaking gutters and downspouts can cause serious damage to a building s interior as well as exterior and repairs can be expensive. To limit the effects of thermal expansion in gutters 50 ft. As with gutters a downspout s capacity must match or exceed the expected runoff. Section ii design data record on appropriate engineering paper.

The amerimax home products flex a spout downspout extension has the amerimax home products flex a spout downspout extension has a green color and rigid corrugated design for versatility. First we will find the maximum amount of rain that will be captured in gallons per minute. This wizard makes it easy to calculate the roof design area by providing various shape calculations and the calculation for vertical walls area per international plumbing code ipc. We will use the larger of the two or 310 sq ft for our first calculation.

The gutter outlet capacity should suit the downspout capacity. I certify that the roof gutter and downspout type size gage roof gutter slope and mounting.