Description: Copper downspouts are usually shop fabricated using 16 or 20 oz. cold rolled copper. Plain and corrugated, round and rectangular downspouts are typical. Other decorative downspout designs can also be fabricated.
Special Conditions: Downspouts should be installed vertically wherever possible. All horizontal offsets should be sloped in the direction of flow.
10.7A. Typical Downspout Sections
This drawing shows typical downspout cross-sections. Downspouts can be fabricated in any size. Table 10.7A shows the dimensions of standard sizes.
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| Type | Area (Sq. In.) | Nominal Size (Inches) | Actual Size (Inches) |
|---|---|---|---|
| Plain Round | 7.07 | 3 Dia. | 3 Dia. |
| 12.57 | 4 Dia. | 4 Dia. | |
| 19.63 | 5 Dia. | 5 Dia. | |
| 28.27 | 6 Dia. | 6 Dia. | |
| Corrugated Round | 5.91 | 3 Dia. | 3 Dia. |
| 11.01 | 4 Dia. | 4 Dia. | |
| 17.72 | 5 Dia. | 5 Dia. | |
| 25.97 | 6 Dia. | 6 Dia. | |
| Corrugated Rectangular | 3.8 | 2 | 1 3/4 x 2 1/4 |
| 7.73 | 3 | 2 3/8 x 3 1/4 | |
| 11.70 | 4 | 2 3/4 x 4 1/4 | |
| 18.75 | 5 | 3 3/4 x 5 | |
| Plain Rectangular | 3.94 | 2 | 1 3/4 x 2 1/4 |
| 6.00 | 3 | 2 x 3 | |
| 12.00 | 4 | 3 x 4 | |
| 20.00 | 5 | 3 3/4 x 4 3/4 | |
| 24.00 | 6 | 4 x 6 |
10.7B. Downspout Assembly
This detail illustrates the various components of an installed downspout assembly.
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The downspout is joined to the gutter with an outlet tube, see Detail 10.7C. The flanges of the outlet tube are soldered to the gutter. Downspout sections are joined together by soldering. The bottom end of the upper section is inserted into the top of the section below it. Copper straps are used to hold the downspout against the building or structure.
Note: Copper drainage tubes can be substituted for the downspouts in all indicated details.
10.7C. Outlet Tube in Gutter Lining
The length of the outlet tube is a minimum of 4" from the flange edge to the bottom edge. The flange is 3/8" wide. The outside dimension of the outlet tube is 1/8" less than the inside dimension of the downspout.
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The outlet tube is inserted through a hole at the gutter bottom. The hole size equals the outside dimension of the tube. The flange of the tube is soldered to the gutter.
For Additional Information:
- Gutters and Downspouts - Hung Gutters, for information on downspout hangers.
- Gutters and Downspouts - Downspout Hangers, for additional information on hung copper gutters.