Common Area Factor

The common area factor is the mechanism that turns the space you occupy into the larger figure you pay rent on. It is expressed as a percentage — closely related to the load factor — that is added to a tenant’s usable square footage to account for its proportional share of the building’s common areas: lobbies, corridors, shared restrooms, and mechanical spaces. A 15% common area factor means a 2,000 usable-square-foot suite is billed as 2,300 rentable square feet. The terms common area factor, load factor, and add-on factor are often used interchangeably, though buildings may calculate them slightly differently. Because two buildings can quote identical per-square-foot rates while carrying very different factors, the common area factor is essential to any honest comparison. A healthcare tenant should always ask for both the usable and rentable figures and the factor between them before comparing suites, since it directly inflates both base rent and CAM.

The common area factor determines how much more than your usable space you pay for. Confirming it before comparing suites prevents a lower rate with a higher factor from costing more than it appears.

A suite has 2,000 usable square feet and a 17% common area factor, making it 2,340 rentable square feet. At $30/sq ft, the tenant pays on 2,340 — about $10,200 more per year than its usable area alone would suggest.