Determining the grade of landscape; repairing a bathtub.

Landscape contractor Roger Cook shows host Kevin O'Connor several different ways to determine the grade, or pitch, of a landscape. In the ASK THIS OLD HOUSE loft, Roger and Kevin are joined by general contractor Tom Silva and plumbing and heating expert Richard Trethewey to ask, "What is it?" Tom and Richard show Kevin different ways to see what's inside a wall. Richard makes a HOUSE call to help a homeowner repair a bathtub that will not hold water.