Residential building permits were up 27.6 percent in March from the same time last year, with all categories registering gains. Permits to build townhouses and apartments provided the biggest boost to the numbers, with townhouse permits increasing to 103 from 79 and multifamily units rising to 188 to 130. Builders took out 235 permits for single-family houses, compared with 203 in March 2013. All cities reporting permit numbers registered an increase in permits. “I think this is going to be a very good year for housing in Des Moine,” said Creighton Cox, president of C2 Policy Advocates Inc., which compiles the numbers for the Home Builders Association of Greater Des Moines.