At the Concord, Mass., barn conversion, landscaper Roger Cook works on the patio (using bluestone) while inside, wallboard is hung and the heating system installed. Meanwhile, host Kevin O'Connor goes over the interior design with designer Tricia McDonagh, and O'Connor and architect Holly Cratsky tour a suite an Acton, Mass., homeowner built for her elderly parents. On “Ask This Old House,” projects include a handrail for a split-level stairway and a rhododendron that needs transplanting.