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.
USPS Requirements
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.
What Is The”4C” Postal Standard(Or STD-4C)?
- New compartment form factor minimum size requirement of 12″W × 15″D × 3″H
- Eliminates the vertical form factor (5″W × 6″D × 15″H) design
- Introduces parcel locker requirement based on a 1:10 ratio of parcel lockers to customer compartments (there must be a minimum of 1 Parcel Locker for every 10 Tenant Compartments)
- Strengthens security requirements for the entire receptacle
- Standardizes and improves tenant compartment lock design
- Meets Americans with Disabilities Act (ADA) standards
4C Horizontal Wall Mount High Security Mailboxes from National Mailboxes are designed to meet or exceed the USPS specifications outlined above and in the Federal Register/Vol. 69, No. 171/September 3, 2004/Rules and Regulations POSTAL SERVICE, 39 CFR Part 111, Standards Governing the Design of Wall Mounted Centralized Mail Receptacles.
How Do The Regulations Affect How I Buy Centralized Mailboxes?
These three simple questions below will help you determine if you need to use 4C Horizontal Wall Mount High Security Mailboxes from National Mailboxes for your next centralized mail station:
1. Are the mailboxes being used in new construction?
- If Yes then 4C Horizontal Mailboxes or Cluster Box Units (CBU) MUST be used
2. If renovating, are mailboxes simply being replaced using the same rough opening (RO)?
- If Yes then 4B+ rated verticals or horizontals may be used
- If No then STD-4C MUST be used
- If adjusting RO or adding new mailboxes then new 4C rated mailboxes MUST be used
3. Is the mailbox installation inside or outside?
- If inside, choose mailboxes based on answers to Question 2
- If outside and “unprotected” then 4C or CBU products MUST be used
What Does Major Renovation mean?
- A “major renovation” would occur anytime the condition of the wall where the existing wall mounted mailboxes are presently installed is being modified.
- If the cavity of the wall is altered in such a manner the mailboxes can’t be reinstalled on a one-for-one basis, the renovation would be considered “major” and mailboxes complying with the new USPS STD-4C regulation should be installed.
If you have any questions about which USPS mailbox Standard will be applied to a specific project, please contact your local Postmaster or Postal Delivery Planning Official for guidance prior to purchasing any wall mounted mailbox systems.
ADA Compliance
The USPS 4C Standard includes a requirement to meet Americans with Disabilities Act (ADA) standards. The ADA section that covers clear space and reach dimensions is noted below and can be found in the ADA Accessibility Guidelines for Buildings and Facilities Appendix A to Part 36 – Standard for Accessible Design Section 4.2 Space Allowance and Reach Ranges
4C Units shall be designed such that they are in compliance with the following installation requirements:
- At least one customer compartment shall be positioned less than 48 inches from the finished floor
- No parcel locker compartment (interior bottom shelf) shall be positioned less than 15 inches from the finished floor
- No tenant lock shall be located more than 67 inches above the finished floor
- No customer compartment (interior bottom shelf) shall be positioned less than 28 inches above the finished floor
- The USPS Arrow lock shall be located between 36 and 48 inches above the finished floor
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.
