Your building may be growing. That sounds like a ridiculous idea, right? But it may be true. Not physically, of course, but in the way the size is determined.

We have blogged in the past about buildings are measured and the difference between the useable square footage (SF) of a building and the rentable. Here’s a link to our blog post from December 2015. In that post we demonstrate how the common areas of a building are allocated to each tenant based on their share of the building. This commons areas include restrooms, elevator lobbies, electrical rooms, and others. Once the share of the common areas for each tenant is added to the useable area they get to use exclusively, you arrive at the rentable SF. And it’s the rentable SF that is used to calculate rent.

The industry group that determines the methodology of measuring building is called the Building Owners and Managers Association or BOMA. Their main purpose is to create a uniform basis for measuring new and old buildings so that they can be compared with greater accuracy. Periodically, they update the standards and 2017 is a year in which they have done just that.

The architectural firm Gensler just put out a short article about the 2017 update.

Landlords have been adding new amenities to make their buildings more attractive to prospective tenants. These include things like rooftop terraces, tenant lounges, bicycle storage, fitness centers, etc. Some of these amenities are considered common area and should, therefore, be allocated to tenants.

That’s how the building may grow. It’s not really growing, but the common area may increase due to these amenities which increase the allocation to each tenant. Thus, your rentable area may increase.

Many landlords won’t go to the expense of remeasuring their building. Others will already have the data with which to do the calculations. But it’s unlikely that they will try to change the size of your space in the middle of a tenant’s lease term. Typically, they will wait until your lease is up for renewal or you want to expand. Then they will change the size.

This is a legitimate thing for a landlord to do, however. I’m not throwing them under the bus here. Something that is truly an amenity shared by all tenants for which the landlord is not charging a separate fee is fair game for being included in the common area calculations.

Just know that this may occur and be prepared with a corporate real estate advisor like REATA to negotiate your next extension, expansion or relocation.

Bob Gibbons is a Real Estate Advisor & Tenant Advocate with REATA Commercial Realty, Inc. which is a tenant advisory firm based in Plano, Texas. Bob serves companies in Plano, Frisco, McKinney, Allen, Richardson, Addison, Dallas and the surrounding areas and specializes in companies which lease or buy office and warehouse properties.