Cluster Mailbox Installation for HOAs and Businesses

What a cluster box unit is

A cluster box unit, often shortened to CBU, is a freestanding pedestal with a bank of locked compartments, an outgoing mail slot, and usually one or two parcel lockers. Newer neighborhoods, apartment communities and office parks use them in place of a box at every curb. The carrier opens the whole front with one Postal Service lock and fills every compartment in one stop.

Because one unit serves many addresses, the rules are tighter than for a single curbside box. The Postal Service lays them out in its handbook for builders and developers, Handbook PO-632. Everything we say about who decides what on this page comes from that guide.

Who is responsible for what

Three parties are involved, and most problems come from mixing them up.

• The Postal Service decides the mode of delivery and where the equipment goes, and it supplies and installs the master lock.
• The builder, developer or association buys the unit and pays for installation. After that, the property owner is responsible for maintenance, repairs and replacement.
• The installer, which is us, sets and anchors an approved unit where USPS has approved it, following the manufacturer’s instructions.

That is why the first step in our process is a call to the post office, not a call to us. A board that orders a unit and pours a pad before asking can end up with a mail station the carrier will not serve.

The pad and the anchors

A cluster unit is tall, top-heavy and gets pulled on every day, so the base matters more than anything else. The unit bolts down to a concrete pad through its pedestal. Each manufacturer publishes the pad size, the anchor type and the bolt pattern for its units, and we follow that manual for the model you bought.

The Postal Service guide includes sample pad drawings, and it tells installers to follow each manufacturer’s instructions. So we treat the drawings as examples and the manual as the rule. If an existing pad is cracked, tilted or too small for the new unit, we will show you photos and price a new pad as its own line before anyone anchors to the old one.

Replacements after damage

Most of our calls for cluster boxes are replacements: a unit hit by a vehicle, pried open, or rusted at the pedestal. If the pad is sound, the old unit unbolts and the new one goes on the same anchors or new ones beside them. Tell your post office before the swap so mail can be held and the lock can be moved. We do not handle the mail or the Postal Service lock at any point.