CHICAGO-Law firms, the gorilla-size user of the classiest space in any large market, will be facing a space crunch in the next two years, according to a new Jones Lang LaSalle study. Thanks to a drop-off in development, big-block availability will likely dwindle in core markets by 2012, either spurring new office properties (blasphemy, up until this quarter) or sparking massive renovation and retrofits of the nicer class B and C buildings, according to JLL’s Global Law Firm Office Perspective report.

Most US cities are still experiencing a tenant-friendly market, but even experts agree that a flight to quality has caused class A space to spike in demand in areas such as Washington, DC and San Francisco. More than one-third of the 73 large law firms in the nation’s capital are looking for space, JLL says. Even in Chicago, where only a handful of the city’s 53 large firms (occupying more than 50,000 square feet) are actively on the market, a joint venture of Trammell Crow and Insite announced Monday that it is planning a one-million-square-foot office tower downtown, in part due to planned demand by 2014.

Of course, users of less than 50,000 square feet will continue to find exponentially more deals in each market, says John Sikaitis, director of occupier research for JLL. The dichotomy of the trophy and lesser-class buildings will continue as long as the job market lags. However, large users will likely see a tightening begin. “The recent uptick in leasing activity, coupled with limited development activity, means that over the next 12 to 18 months we could see limited space options emerge for large users,” he says.

Tom Doughty, international director of JLL’s Law Firm practice, said law firms should realize that now is the time to lock up favorable rates while the best space options are available. A few cities still have rent discounts, such as up to 15% in Dallas, or 20% in Miami and St. Louis, he says. “Activity will pick up again. It won’t be a stampede, but I think in a couple years you’re going to see higher rents in anticipation of law firm demand,” Doughty tells GlobeSt.com.