One of the first steps in evaluating a commercial space is determining the total rentable square feet. While this might seem like a straightforward calculation, it unfortunately doesn’t always end up being so simple.
The general rule of thumb is to allow anywhere between 125 and 225 of usable square feet of office space per person. This of course, depends upon the type and style of the business and the work space layout. These figures can vary based upon special needs such as extra-large conference rooms or storage requirements, but will include normal amenities within a general use office. The following office space allocations can be used to help estimate the amount of “usable” office space required for your business based upon uses. Any common area load factors will need to be added on to determine the “rentable” area.
In a nutshell, usable square footage is the actual space you occupy from wall to wall. Usable square footage does not include common areas of a building such as lobbies, restrooms, stairwells, storage rooms, and shared hallways. For tenants leasing an entire floor or several floors, the usable square footage would include the hallways and restrooms exclusively serving their floor(s).
Rentable square footage is your usable square footage PLUS a portion of the building’s shared space. As mentioned above, shared space can be anything that is outside of your occupied space and is of benefit to you (lobbies, restrooms, hallways, etc). As a tenant in a commercial space, you pay for a portion of the shared space and thus your monthly rent is always calculated on RSF.
The increase in the the rentable square footage above your usable square footage is referred to variously as the “load factor,” “common area factor,” or “add-on factor.” This is generally in the 10-15% range and can be higher in some buildings. When evaluating commercial real estate space options, you’ll want to be aware of this factor so you know exactly what you’re getting and what you’re paying for.
Calculating the load factor is pretty straightforward. First, find out how much total floor area a building has. Then, subtract the shared square footage to determine the usable square footage. The owner or owner’s agent should be able to give you these numbers. Then divide the total floor space by the USF to get the load factor.
Load Factor = Rentable Square Feet / Usable Square Feet
Example: A 100,000 square foot building has 15,000 square feet of shared space. The usable square footage is 85,000 square feet. The load factor would be 1.176 (100,000 / 85,000). That would also be the same as saying the building has a load factor of 17.6%.
Below are examples of what you can expect to allot for square footage:
Typical President’ s office or Chairman of the Board
200 to 400 sf (3 to 5 windows in length)
Typical Vice-President’ s Office
150 to 250 sf (3 to 4 windows in length)
Typical Executive’ s Office
90 to 150 sf (2 widows in length)
Open Space Workstations
Benches or cubicles 60 to 110 sf per person
Work Group Areas
80 to 100 sf per person
Allow 1-100 sf for every 10 open space or work group work stations
15 sf per person: theater style
25 to 30 sf per person: conference seating
8 to 9 ft. wide with 30″ counters on either side. The length depends upon amount of usage
125 to 200 sf Receptionist and 2 – 4 people
200 to 300 sf Receptionist and 6 – 8 people
7 sf per file with a 3′ to 4′ aisle width
Allow 12″ for bookshelf width
175 to 450 sf with seating for 4 – 6
15 sf per person, not including kitchen. Kitchen should be 1/3 seating area
ADA Restroom within the space
55 sf for a 1 seater and 30 sf for each additional seat
Click here for OSHA Quantity Standards
Corridors within the space
20% to 30% of the total usable area
1 lineal foot for 4 coats
Water Coolers/Drinking Fountains
1 unit per 75 employees
Suggested Column Spacing
28′ to 30′ per bay
Suggested Window Mullion Spacing
4’6″ to 5′. This determines office width
The actual amount of usable square feet required may differ due to varying conditions such as floorplate configuration, column spacing, and circulation areas. The actual amount of rentable square feet required may differ depending on the allocations of common areas in a given building. Check out this great office space calculator.