That hammering noise you hear down the street may be home building in Hall County — and quite possibly the start of a residential boom not seen since before the Great Recession. So far this year, nearly 3,000 homes, apartments, condominiums and townhomes have been approved or are under construction throughout Hall, according to a survey last week of area governments. It’s quite the reversal of 10 years ago, when, during the nation’s worst economic downturn since the Great Depression, construction came to a screeching halt — in 2010, literally just 1 building permit was issued in Gainesville.