Common Area

Common area, in commercial real estate, is the part of a building or shopping centre that is shared by all tenants and used to access, service, or enjoy the property. It is the lobby, the lifts, the corridors, the public restrooms, the parking deck, the loading dock, the landscaping, the rooftop plant. In a strict legal sense it is the property the tenant does not lease but does pay to maintain, through its share of CAM (common area maintenance) charges.

Why common area definitions matter

The line between "common area" and "tenant area" is the line between what the landlord controls and what the tenant controls. Two consequences:

Operating cost allocation. Operating expenses related to the common area get included in CAM and passed through (or absorbed, depending on lease type). Operating expenses related to the tenant's premises get paid by the tenant directly, or are part of base rent in a gross lease. A lease with a vague common-area definition opens the door to disputes about which costs sit in which bucket.

Square footage measurement. The "rentable" area a tenant pays rent on is typically the "usable" area (the actual leased space) plus the tenant's pro rata share of common area. The ratio is the load factor (or "core factor"), and it directly affects how much rent the tenant pays per usable square foot. A 15% load factor means a 10,000-usable-square-foot tenant pays rent on 11,500 rentable square feet. Different buildings calculate this differently; some include only "common area on the floor," others include lobbies, mechanical rooms, and shared amenity spaces.

Three layers of common area

Most office buildings have a three-tier hierarchy:

Building common area is shared by everyone in the building — main lobby, stair towers, lifts, ground-floor amenities, plant rooms, central restrooms.

Floor common area is shared by tenants on a single multi-tenant floor — corridor, on-floor restrooms, lift lobby, electrical and telecom closets.

Tenant amenity space is a category that varies by lease — gyms, conference centres, food halls, rooftop gardens. Sometimes these are common area paid through CAM; sometimes they are amenity-fee structures separate from CAM.

A well-drafted lease lists which areas qualify under which tier and how each tier's costs flow through.

Tenant control concerns

Even though the common area is not leased to the tenant, the tenant has economic and operational interests in it:

Reasonable access — the lease should guarantee the tenant 24/7 access to the leased space, including elevator service, electrical supply, and security, with carve-outs only for genuine emergencies and announced maintenance.

Standards of maintenance — the lease should specify that common area is maintained to the standard of a "first-class office building" (or whatever class is appropriate). Without this, the tenant has no contractual leverage if the lobby starts looking shabby.

No material changes without consent — major reconfigurations (adding a coworking lounge, repositioning the lobby, changing the building's use) can affect tenant operations. Most leases give the landlord broad rights to modify common area; tenants should negotiate consent rights for changes that materially affect their access or use.

Special rights — for retail tenants, exclusivity over a specific zone of common area (signage, mall frontage, sidewalk display) is a negotiated point and should be express in the lease.

Common area in retail vs office

In retail leases, common area is more contentious because tenants compete for foot traffic. Mall leases often define common area broadly (including parking, food court, plaza), give landlords specific rights to reconfigure it (add kiosks, run promotional events, install signage), and structure CAM as a per-square-foot charge that is reset annually rather than reconciled to actual costs. Tenants in malls also typically have rights tied to common area: minimum operating hours for the centre, marketing fund contributions, sometimes co-tenancy clauses tied to occupancy of the rest of the centre.

In office, common area is more administratively defined and the tenant's interest is mostly in cost allocation, access, and maintenance standard.

APAC variations

In Hong Kong, "common area" is well-defined in most modern office leases but historically suffered from informal practices in older buildings. The Building Management Ordinance and the Code of Practice on Building Management Agreements provide a backbone, and Grade-A buildings follow it.

In Singapore, the equivalent definitions are typically embedded in the Master Plan and the building's strata title documents (where applicable), with the lease referencing them.

In Japan, 共用部 (kyōyōbu) is the standard term for common area. Japanese office leases historically allocate common-area costs through fixed monthly 共益費 rather than reconciled CAM; the definition of what is included is usually short and accepted by reference to building management practice rather than negotiated in the lease itself.

If you have a stack of leases with different common-area definitions, load factors, and access rights, having those captured per lease in the same field structure lets portfolio analytics actually compare apples to apples. LeaseTrace extracts those fields with citations back to the source PDF.