San Diego County construction activity, measured in building permit valuations, rose 47 percent from a year ago in the first nine months of 2011, according to data released Oct. 24 by the Construction Industry Research Board.

Builders took out permits for residential and commercial projects — including new construction, expansions and renovations — worth $1.83 billion from January through September, compared with $1.24 billion in the first nine months of 2010. The total also beat the comparable period of 2009, though fell short of the $1.98 billion seen in the same period of 2008.

Figures showed residential building activity up 32 percent, to just over $1 billion, led by a 145 percent jump in the value of multifamily projects. Single-family permit valuations were up 10 percent from a year ago.

Nonresidential building was up 73 percent, to $819 million in permits, although 62 percent of that dollar total was for renovations and expansions rather than new construction, according to data from the nonprofit industry research bureau.