The multi-unit housing sector saw an uptick in starts and building permit activity in August, adding a boost to the otherwise slumping market. Last month, construction began on 13,900 units in buildings with five or more units, according to the U.S. Commerce Dept. That is the highest number of starts since February 2009. Despite the rise in activity, the sector is still down year-to-date, with 67,000 units started in the first eight months of 2010 compared to 74,400 during the same period in 2009. Building permit activity suggests the sector could see some improvement in the future. Applications for 84,500 units in large multi-unit buildings were filed in the first eight months of 2010, compared to 80,600 for the same period in 2009.