Carpentry Squares; Brick Patio Ask This Old House : Season 6 Episode 2

Up in the loft, general contractor Tom Silva shows host Kevin O'Connor a few different types of "squares" used for general carpentry. Then Tom and Kevin, along with plumbing and heating expert Richard Trethewey and host Kevin O'Connor ask, "What is it?" Afterward, Roger helps a homeowner build a new patio using concrete paving bricks.