The Arlington County Board voted last night to adopt strict limits on house sizes, in response to citizen complaints about the number of oversized houses cropping up in established neighborhoods. “It was dramatic because we took an action targeting the most egregious McMansions we’ve experienced,” board Chairman Jay Fisette (D) said of the 4 to 1 decision. The vote capped four years of debate over what to do about house sizes in the county, where many bungalows and cottages have been torn down to make way for much larger houses. The restrictions will be Northern Virginia’s toughest measures aimed at so-called McMansions. The guidelines, which will apply to new homes and renovations, will limit the amount of room that a house, garage and driveway can occupy on a lot, on a scale that varies according to lot size. For most residential lots in the county, that means the house alone can occupy 30 percent of a lot, or have a footprint of about 2,160 square feet. Currently, a house, driveway and garage can occupy 56 percent of a lot. Developers and citizen activists who had opposed the limits expressed dismay, saying the decision could hurt the average homeowner trying to build a deck or add on to a house.