When you wish to install downspout you should also install a new gutter system to ensure that your new home weather drainage system is consistent and free of trouble. When doing this you should be sure that you have a partner to help you out with extra hands. Even if your walls are concrete the job is not a difficult task.
Step 1 - Prepare the Roof for Gutter and Downspout Assembly
Be sure to install the proper mounting brackets for the gutter because when this is installed correctly then the installation of the downspout will be easier. Install the gutters on the brackets using the proper hardware. If your gutter comes with a cover wait to install that until you have the downspout installed at the exit end of the gutter.
Step 2 - Install the Downspout
Attach the downspout elbow to the gutter assembly. Make sure that you use a sealant like silicone to ensure that there are no leaks between the downspout and the gutter. Attach the extensions to the downspout to the elbow. Make sure that you have enough to run the downspout pipe from the gutter to about 6 inches from the ground.
Step 3 - Attaching Downspout to Building
Decide how many duct brackets you wish to use. A good rule of thumb is one every 18 inches to 2 feet. Once you figure where to put the brackets, drill holes in the concrete on each side of the downspout to accommodate the anchors. When the holes are drilled put the bracket around the downspout lining up the holes. Put the masonry anchor in the hole and tap it. Using the nut driver or socket wrench and socket, tighten the bolt down to expand the anchor in the concrete to hold it in place securely. Repeat this procedure for each of the brackets that you need to install.
Step 4 - Finish Assembly
Once you have completed installing the brackets ensure that you put sealant on each of the joints and seams where the downspout is assembled so the water will run through and deposit at the bottom of the assembly. You have a couple choices for drainage once the downspout is installed. You can put a bucket at the bottom of the downspout and collect rainwater for future watering needs, or you can install a concrete splash guard to help protect your ground from eroding when the water drains down the pipe.
Put the bottom elbow on the downspout to direct the water away from your home and install the gutter cover. Wait about 4 hours for the sealant to dry and cure. Test for leaks by using a water hose to run water through the gutter and down the downspout. If you find any leaks just wait for the area to dry, or wipe with a dry cloth and apply more sealant in the leaking areas. Test again once the new sealant has been cured.