Horizontal 4C mailboxes are, as the name suggests, a unit of horizontal mailbox units meant to serve an entire community or complex of businesses with a need for quick, convenient, centralized mail delivery. They can be used in both indoor and outdoor environments, such as lobbies and outdoor kiosks, making them a versatile choice.
All horizontal 4C mailboxes that receive USPS approval are constructed with the requirements of USPS-STD-4C in mind, though an installer, contractor, or architect may need to make some modifications to an installation to ensure that all of the USPS requirements are met for a 4C horizontal setup.
The Correct Height. Ensuring that all parts of a 4C horizontal mailbox setup are at the correct height is a must. All heights are measured from Above Finished Floor (AFF.)
All customer locks must be no higher than 67 inches AFF. In addition, there must be at least one customer compartment (not lock) that’s no higher from the finished floor than four feet (48″.) All customer compartments can also be no closer to the finished floor than 28 inches.
The master lock used by the USPS to deliver mail, or the arrow lock, must be between 36 and 48 inches AFF. However, as horizontal 4C mailboxes are built with USPS requirements in mind, this will likely not be an issue when meeting the other requirements.
Parcel Lockers. If there will be at least ten customer compartments in your horizontal 4C setup, at least one parcel locker is required by the USPS. When there are twenty customer compartments or more, at least two parcel lockers are required, and so on. A 1:10 ratio is best practice. If there are fewer than ten customer compartments, parcel lockers are still recommended for package security and ease of delivery.
All parcel lockers must be at least 15 inches AFF for accessibility (measured from the bottom shelf.) Typically, parcel lockers are found at the bottom of a 4C horizontal mailbox setup for this reason, but they can be installed beside customer compartments if additional units are needed.
ADA Reach and Space Requirements
Once confident you will be able to meet USPS requirements for your 4C mailboxes, you must ensure that you can meet the requirements set forth by the Americans With Disabilities Act. This is necessary to accommodate wheelchair users, with requirements for floor space and reach height. Once again, all measurements are from Above Finished Floor (AFF.) At least five percent of all indoor mailboxes must meet the ADA requirements below:
Forward Reach. Adequate floor space must be provided to allow wheelchair users to reach their compartments when using a forward approach. No obstructions can be present. As of 2010, at least five percent of customer compartments must be no higher than 48 inches AFF and no lower than 15 inches AFF. The minimum height refers to the height of the bottom shelf of a customer compartment.
Side Reach. The 2010 ADA requirements for side reach height are identical to those for forward reach height. However, these requirements are to be met when a wheelchair user will be taking a side approach to his or her mailbox. Once again, at least five percent of all indoor customer compartments should be within 15″ to 48″ from the finished floor.
If you have any questions regarding the correct installation for 4C horizontal mailboxes, contact us at National Mailboxes today.