In Houston, more than 3,200 janitors clean the offices of some of the largest and most powerful corporations in the world: JP Morgan Chase, Shell, Exxon Mobil, Chevron, Wells Fargo, KBR and Marathon Oil, to name a few. For their labor, they are paid an hourly wage of $8.35 and earn an average of $8,684 annually. Two janitors together would earn about $17,300 a year—still well below the poverty line of $22,314 for a family of four.

Yesterday, the contract between the janitors and the cleaning contractors expired. SEIU Local 1 spent the past month trying to reach an agreement to raise the janitors’ hourly wage to $10 over the next three years. But the contractors countered with an offer of a $0.50 pay raise phased in over five years and—according to SEIU spokesperson Paloma Martinez—said that they “wouldn’t budge.” The contractors claimed that the building owners and tenants—the aforementioned corporations—aren’t willing to pay anything close to a living wage.

In response the janitors voted to authorize their bargaining committee to call a strike. For workers already struggling on sub-poverty wages, this was no easy decision.

“The workers were really insulted by the offer,” said Martinez. “The contractors said they weren’t going to move and they blamed it on the building owners, but we all know the state of the real estate market here.”

With the city enjoying the fruits of the energy industry, Houston’s commercial real estate market is indeed the best performing market in the United States in terms of demand. It has the highest number of new corporate real estate projects in the nation, vacancy rates below the national average and rising rental rates.

Nevertheless, the city’s janitors are among the lowest paid in the nation, with workers in cities with far weaker real estate markets earning a significantly higher hourly wage: Cincinnati ($9.80), Cleveland ($10.30), Detroit ($10.97) and Chicago ($15.45) are a few examples.