Constructing paving brick patio; carpentry “squares”

Up in the ASK THIS OLD HOUSE 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, ask, "What is it?" While making a HOUSE call, landscape contractor Roger Cook helps a homeowner build a new patio using concrete paving bricks.