Elbows are used to attach a gutter connector to a downspout not only at its top but also at the bottom to run an extension out away from the foundation of the structure. Wherever a change of direction in a downspout is needed, an elbow is necessary. A typical gutter attaches to the downspouts via a connector. The connector sticks out from a hole in the gutter. To this connector, an elbow is attached angling back towards the siding. A straight extension piece reaches to the siding, where another elbow is attached to the downspout. At that point, elbows are used if the downspout needs to move around an obstacle, or where it channels water away from the home at the ground level. To attach another elbow at the base of the downspout to direct the water away from the storm drain, follow this how-to.
Step 1: Redirect Downspout
Some municipalities offer incentives to homeowners who disconnect their downspouts from the storm drain and direct rainwater either into a rain barrel or onto a downspout ramp. This reduces pressure on the storm drain system. If you want to do this, the first thing to do is to cut the downspout off a few feet from where it enters the storm drain. Measure up between 2 to 3 feet from the ground and use the hacksaw to cut the lower section off the downspout. Once complete, remove it from where it enters the storm drain.
Step 2: Attach Elbow
Attach the new downspout elbow fixture to the shortened downspout. The lower, open end of the elbow should be facing away from the house. Insert the bottom of the downspout into the top entry of the elbow. The downspout should taper in slightly as it approaches the ground. With the end inserted into the elbow, draining water will run properly through the elbow. Use a hose clamp to tighten the elbow to the downspout. Flexible elbows that have a little give to them work better for this use.
Step 3: Attach Extension
You can probably use the piece of downspout that you cut off from the bottom as your extension. Insert the bottom of the elbow facing away from the house into the larger end of the extension. Fasten the second hose clamp around the two pieces and tighten.
Step 4: Position the Extension Over the Runoff Ramp
With the extension in place, position the runoff ramp directly below the angled-out extension piece. Prop up the backside of the ramp so it slants, although it is built with preformed pitch.
Step 5: Test and Modify if Necessary
Test the strength of the hose clamps. Tug on the extension piece and the elbow to make sure the clamps have a good hold. There is not much weight pulling on the clamps this far down the downspout. If for some reason it will not hold, sheet metal screws may be required. Drill two small pilot holes in both the top and bottom connection points on the elbow and insert two small sheet metal screws to secure the connection.
Consider sealing around the sheet metal screws so water does not leak out in heavy rainfall. One of these two methods will work to secure the elbow joint at the bottom of the downspout. With the added extension, draining water will run through the downspout, onto the runoff ramp and away from the home, keeping it out of the storm drain.