THIS OLD HOUSE opens a new season with work on a 300-year-old farmstead that is rich in Colonial history. Homeowners Joe and Becky Titlow plan to preserve the historic part of the house while adding space and modern amenities with two small additions. Architect Dan Quaile presents the plan using a remarkable model generated from a 3-D printer, while general contractor Tom Silva inspects the structure and historic window sash, which will be restored. In the basement, plumbing and heating expert, Richard Trethewey, finds the relic of an antique water pump system, and a newer mechanical system that contains some inefficient and unsafe aspects. Master carpenter Norm Abram is concerned about the high water table, especially when it comes to excavating for the new additions. Landscape contractor Roger Cook considers the half-acre lot and what the homeowners would like to add - a storage shed, raised garden beds, a new driveway and stone walls. The bulk of the landscape work will be clearing and reclaiming nearly half of the back yard that has been overwhelmed by brambles and invasives.