Installing a sturdy and welcoming double mailbox setup significantly elevates your home's curb appeal while ensuring efficient mail organization. This guide provides detailed DIY double mailbox post plans, walking you through each phase from initial measurement to the final coat of paint. Whether you are replacing a sagging old unit or establishing a new point of pride for your residence, a well-constructed post is the foundation for a functional and attractive entryway.
Planning Your Double Mailbox Layout
Before touching a saw, precise planning prevents future headaches and ensures compliance with local regulations. The United States Postal Service (USPS) provides specific guidelines regarding mailbox placement and height, which your local building department may also enforce. Generally, the bottom edge of the mailbox should be situated between 6 and 8 inches above the road surface, with the box itself facing outward for maximum visibility.
For a dual configuration, you must determine if the mailboxes will share a single post or utilize two separate posts flanking the driveway. A shared post is often more cost-effective and space-efficient, but it requires careful balancing to ensure the structure remains stable. Consider the width of your largest envelopes and packages to guarantee the ledge is long enough to accommodate daily deliveries without obstruction.
Gathering Materials and Tools
The strength of your mailbox post depends entirely on the quality of the materials selected. For a DIY double mailbox post, you will need a 4x4 or 6x6 pressure-treated wooden post, concrete mix, a Sonotube or similar form tube, and galvanized bolts or heavy-duty brackets. Selecting a post that is at least two feet longer than the final desired above-ground height is recommended; the excess length is buried deep into the ground to resist twisting and heaving.
Essential Tools:
| Post hole digger | Level | Tape measure |
| Power drill | Concrete mixing tub | Shovel |
Protective gloves and safety glasses are non-negotiable, as contact with concrete and treated wood can be hazardous. Having a second person to assist with leveling the post during the concrete setting process is highly advised.
Digging the Post Hole
The depth of the hole is the single most critical factor in the longevity of your mailbox post. A general rule of thumb is to bury one-third of the post's total length. For a standard 8-foot 4x4, this means a hole depth of approximately 2.5 to 3 feet. The diameter of the hole should be three to four times the width of the post to allow for proper concrete placement.
Mark the exact location with spray paint and dig the hole using a post hole digger or auger. It is vital that the bottom of the hole is firm, undisturbed soil rather than loose dirt. If the hole walls are crumbly, consider installing a compacted gravel base to prevent settling over time. The hole should be dug deep enough to accommodate the postal regulations regarding burial depth, ensuring the structure is protected from frost heave in colder climates.
Constructing the Mounting Jig
To ensure the dual mailbox layout is perfectly symmetrical and level, creating a jig is a pro-level move. Before placing the post into the concrete, cut a small board to act as a spacer that represents the width between the two mailbox mounting holes. Secure this spacer between two temporary blocks to maintain the exact distance required by your mailbox units.
Place this jig at the top of the post where the mailboxes will be installed. This allows you to verify the alignment of the mounting brackets before the concrete hardens. By doing this, you guarantee that the mailboxes will sit parallel to the ground and mirror each other, creating a polished and professional appearance.
Setting the Post in Concrete
Pouring the concrete is the point of no return, so preparation is key. Mix the concrete according to the package instructions until it reaches a thick, peanut butter-like consistency. Pour a few inches of concrete into the bottom of the hole and place the post on top. Use your jig to position the post precisely before filling the hole.
Carefully fill the hole around the post, packing the concrete firmly with a stick or tamper to eliminate air pockets. Ensure the post remains perfectly level in both directions using your level tool. The top of the post should be slightly angled away from the house to promote water runoff. Allow the concrete to cure for at least 24 hours before attaching any mailboxes or applying stress to the structure.
Attaching the Mailboxes
Once the concrete has fully cured, you are ready to install the hardware. Slide the mounting brackets or straps onto the post to their final position, using the jig you created earlier as a guide. Mark the screw holes, drill pilot holes into the wood, and secure the brackets with rust-proof screws or bolts. Double-check that the distance between the two brackets matches the pre-drilled holes on the back of the mailboxes.
Hang the mailboxes onto the brackets and verify that they open and close without rubbing against each other. This final step ensures that your DIY double mailbox post plans result in a functional, everyday storage solution. A fresh coat of paint or a durable sealant will protect the wood from the elements, transforming your construction project into a permanent, attractive feature of your home.
