The kitchen addition to the Winchester, Mass., house is nearly complete as a mineral-wood insulation is sprayed into the walls, so cabinetmaker Jeff Peavy goes to work. Meanwhile, contractor Tom Silva installs double-hung windows in the sun porch; roofer Tom Evarts describes what his crew has been doing; and plumbing-heating expert Richard Trethewey shows host Steve Thomas the water-supply lines and the heating-and-cooling system. On “Ask This Old House”: Landscaper Roger Cook and garden-tool expert Paul Schneider assess different types of hand pruners; Silva helps two homeowners repair and reinstall broken shutters; and Trethewey discusses water heaters and visits a house with a tankless hot-water system.