---
title: Building Area Classification
tags:
  - status/draft
  - topic/construction
  - type/encyclopedia-entry
---
# Building Area Classification

* G = Gross Area
* R = Rentable Area
* U = Usable Area
* N = Net Area

$$
G > R > U > N
$$

## Gross Area (GSF)

Gross Area is the total floor area of a building.

Whether the area includes exterior wall area
depends on the relevant standard.

* International Building Code (IBC):
    measured to the interior face of exterior walls.

* Building Owners and Managers Association (BOMA):
    total footprint, including exterior wall thickness.

## Rentable Area (RSF)

Rentable Area includes tenant exclusive space (usable area)
plus a pro-rata share of common areas (load factor).

$$
\text{Rentable Area} = \text{Usable Area} \times (1 + \text{Load Factor})
$$

### Usable Area (USF)

This may be synonymous with Saleable Area

Usable Area is the tenant's exclusive space.
the area physically occupied and controlled by a specific tenant.

Usable Area includes:

* Primary functional areas (offices, workstations, meeting rooms)
* Internal circulation within the tenant's space
* Columns, recesses, and other features within the leased boundary

But excludes:

* Common corridors and lobbies
* Shared service areas
* Major vertical penetrations (elevator shafts, stairs)

### Net Area (NSF)

the actual functional, programmable space.

Also called Net Assignable Area.

Net Area includes:

* Actual functional program spaces (offices, classrooms, apartments)
* Space planned for specific uses in a program

But it excludes:

* All circulation (even within tenant space)
* All service and support spaces
* Structural elements, wall thicknesses

## Building Efficiency

Building efficiency is the ratio of usable or rentable area to gross area.
This denotes what percentage of the building is functionally usable.

$$
\text{Building Efficiency} = \frac{ \text{Net Assignable Area} }{ \text{Gross Area} }
$$

A higher percentage means less area is lost to structure,
mechanical spaces, or circulation.

* Office buildings: 75-90%
* Residential buildings: 80%+
* Hospitals and laboratories: 50-65%
