Recovering contractor Tom Silva returns to the Winchester, Mass., colonial-revival house as polystyrene crown moulding is installed. In the kitchen, soapstone counters are being put into place by Glenn Bowman, who also takes host Steve Thomas to the Vermont quarry from which he mines soapstone. And in the garage, craftsman Roger Jurczak installs doors designed to look like the 1920s originals. On “Ask This Old House”: “Housecall” segments include a home “critter-proofing” and the installation of a shower faucet that prevents scalding. Also: robotic lawnmowers are examined by landscaper Roger Cook and host Steve Thomas.