Kevin O'Connor joins architectural historian Maggie O'Neill to explore colonial revivals. Later, he and Zack Dettmore work on framing the upstairs addition. In the attic, Richard Trethewey explains that one mini-duct high velocity system is enough. In the basement, he and Lev Minsky install tubing on the main trunk line. Zack installs special hardware in the kitchen to prevent wall wracking.