Whether you have just added siding to your home or you are replacing your existing gutters, you need to hang the downspouts correctly. Fastening a downspout to vinyl siding does not require anchors. Professional gutter installers use zip screws to secure the downspout straps. Zip screws bite into the siding without going into the outside wall of the house. You can buy zip screws and straps at home improvement centers.
Things You'll Need
Zip screws 1 1/4-inch long
Cordless drill or screwdriver
1/4-inch socket attachment for drill or screwdriver
Fasten the downspout to the gutter elbow with sheet metal screws according to the manufacturer's instructions.
Place a downspout strap at the top where it meets the elbow. Secure one end of the strap to the siding with a zip screw and a cordless screwdriver with 1/4-inch socket attachment. Screw the fastener in slowly and release the trigger on the drill just before the screw head meets the vinyl siding. Tighten the screw just enough that the back of the screw head is flush on the siding.
Bend the strap across the downspout and secure the other end to the siding with a zip screw.
Attach another strap 18 inches from the bottom of the downspout. Secure the strap in the same manner as you did the upper strap. Place additional straps every 10 feet of the downspout length if it is a long downspout, or just one more between the upper and lower strap if the downspout is less than 10 feet long.
Apply silicone caulk around each zip screw head with a caulking gun where the head meets the vinyl siding. This prevents water from leaking into the siding around the screw.