Postcodes
Postcodes for Apartments and Shared Buildings
All flats in a building usually share one postcode, so the unit number does the rest. Learn how to write apartment addresses and find units.
Updated 14 October 2026 · 2 min read
Most apartments and flats in the same building share one postcode. The code gets mail to the building's delivery group, and the unit number identifies the individual home. In large complexes with several blocks, an extra building or block name is needed too.
How the pieces fit
An apartment address generally has these elements:
- the recipient name
- the unit, flat or apartment number
- the building name or number and street
- the town, with the postcode in its local position
The postcode alone cannot separate one flat from another. See postcode structure explained for what a code does identify.
Why unit details matter
Sorting machines may deliver the item to the right building, but a missing unit number leaves a carrier with a stack of mail and no clue. A common cause of failed deliveries in blocks is a missing or ambiguous unit identifier. See common postcode mistakes.
Large complexes
Large developments can have several blocks, entrances and floors. Delivery staff may need:
- the block or tower name
- the entrance letter or number
- the floor
- an access code or a phone number for the intercom
A postcode that covers the whole estate cannot give those details. Compare with postcodes for large organisations, where one code stands for a high-volume receiver.
Where the front door is
In a building with several entrances, the address may be on one street while the door is on another. Map pins from a postcode land in the middle of the area and do not help; see why postcodes cannot pinpoint exact locations.
Helping couriers
Include the unit number in a dedicated field, add entry instructions and, where a delivery must reach a specific entrance, give a precise map location. A UPCS code for the entrance cell can be added to the delivery notes. It supplements the normal address and postcode, and it is not an official postal code.
Online forms
Make sure the address form has an "apartment, suite or unit" field, as covered in postcode formats in online forms.
Frequently asked questions
Does each apartment have its own postcode?
Usually not. Most apartments in a building share the building's postcode, and the flat or unit number tells them apart.
Where should I put the flat number?
Before or alongside the street number, following the local convention, and always before the postcode line.