At the Winchester, Mass., house: a new doorway is cut into the basement foundation; exterior paint is stripped using nontoxic chemicals; architect Donald Striling and homeowner Kim Whittemore discuss the house's asymmetrical dormers; Whittemore and host Steve Thomas shop for windows for the addition. On “Ask This Old House,” projects include a toilet that's constantly refilling, a window pane that needs replacing and a window sash that needs reglazing. Also: contractor Tom Silva makes a “housecall” to repair cracked plaster in a condominium ceiling; and landscaper Roger Cook helps a homeowner remove a tree stump with a stump grinder.