The number of homeowners in Tarrant, Johnson, Parker and Wise counties falling behind on their mortgages remained flat in December, the CoreLogic research firm says.CoreLogic said 4.6 percent of mortgage holders were at least 90 days delinquent in December, the same as November. But it decreased from a year ago, when 5.3 percent were at least 90 days late on payments.In Texas, the number fell to 4 percent, from 4.8 percent a year ago. And nationally, the number fell to 6.4 percent from 7.2 percent a year ago, CoreLogic said.Also, the area's foreclosure rate was 1.1 percent in December, down from 1.4 percent in December 2011. The foreclosure rate measures the percentage of loans in some state of the foreclosure process.Design Talk plannedJoe and Tracy Self, with guest Tommy Stewart, an architect and planner, will talk about Design and Natural Disasters at the March presentation of Design Talk.The free presentation will run from 7 to 8 p.m. March 13 at the Center for Architecture, 3425 W. Seventh St. in Fort Worth. It is open to the public.It will cover how preparations for a disaster define responses when one occurs. Learn about the role of thoughtful design as related to disasters.Design Talk is sponsored by the American Institute of Architects' Fort Worth chapter.Architecture servicesThe latest Architecture Billings Index in January, an economic indicator of construction activity, is showing its strongest growth since November 2007.The American Institute of Architects said the January score was 54.2, up sharply from 51.2 in December, indicating a strong increase in demand for design services.Moreover, the new projects inquiry index was 63.2, an increase from December's 57.9, the organization said.The ABI reflects the approximate nine- to 12-month lag between architecture billings and construction spending.Transactions3909 E. First St., Fort WorthCharley Bell Properties has bought a 48,350-square-foot building for his company, Bell Brother Moving. Chris Stewart of Coldwell Banker Commercial Searcy Vasseur Group represented the seller, JA Properties Ltd.Braswell Drive and Northeast 28th St., Fort WorthTriple-S Braswell has bought 31.8 acres. Jeff Givens and Amy Baker of Transwestern represented the buyer.Chisholm Trail Parkway, Fort WorthFPMC Fort Worth Realty Partners bought 8.3 acres from Cassco Land Development. Jack Huff and Kyle Poulson of Transwestern represented the buyer.1001-1005 Henderson St., Fort WorthH2E2 Partners bought 39,951 square feet of industrial space. Jerry Alexander, Sarah Everett and Grant Huff of Transwestern represented the seller, Jerry Elmore.270 Miron Drive, SouthlakeDavid and Sonja Coffin have bought a 3,351-square-foot office building for their law firm. The firm will occupy 1,833 square feet, with the remainder leased to a medical user. The building was sold by RCC Miron Office Ltd. Mark Boone of Realty Capital Management represented the seller. Shane Strickland of Glacier Commercial Realty represented the buyer.