A mailbox footing is as important as the mailbox itself. Failure to install an adequate footing for your mailbox will result in structural failure of the mailbox. If done correctly, your mailbox will last a lifetime. If you are planning on installing a mailbox, then you should know vital information on footing installation as well.
Tools and Materials
There are several tools and materials that you will need in order to successfully complete you mailbox footing. You will need a pick and shovel for digging the footer, a concrete trowel for smoothing the concrete, a tape measure and a hammer. As for materials, purchase rebar for strengthening the footing and ready-mix concrete. These materials can be purchased at your hardware store.
Dig the footer hole at least 2 inches deeper than the thickness of the footer. This will keep the footer hidden below the dirt surface. For example, if your footer is 12 inches thick, then dig the hole 14 inches. Use a pick to loosen the dirt and a shovel to remove dirt and square the hole. Save the top layer of grass--if any--so that you can fill in around the new mail box. Dig the footer hole 6 inches bigger than the mailbox. For example, if the mailbox will be 16-by-16 inches, length and width, then make the footer 22-by-22 inches. The larger footer will help support a heavy brick, block or rock mailbox.
Lay rebar on 4-inch bricks in the hole--four across will be enough. The rebar should be 1/4 or 1/2 inch. Install a vertical piece of rebar that is slightly shorter than the height of the proposed mailbox. For example, if the mailbox will be 36 inches high, then drive a 34-inch piece of rebar into the center of the proposed footer before you pour the concrete. Drive one short piece of rebar, and allow it to stick up from the ground 12 inches; this will be the thickness reference for the footer. Pour the concrete to the top of the 12 inch rebar. Paint the top of the 12 inch rebar bright orange so that you can find it in the concrete.
Mix the ready mix concrete in a wheelbarrow, and slowly pour the concrete into the hole. Smooth the concrete with a concrete trowel, and allow it to dry for 48 hours before you install the mailbox.