A San Francisco couple bought a 1970’s house, cheaply built but well-sited, on a beautiful property in the redwoods. Their initial thought was to do some cosmetic upgrades. On our first look at the home, we saw some minor flaws in the plan that, if corrected, would have a significant impact on the quality of the house: A bay window that was once meant to expand the bedrooms did not adequately do so; it was falling off anyway, so we rebuilt that element to be part of the house. The lower level, spacious but unfinished and only accessible from the outside, was redeveloped into a family room; with a new interior stair connecting it, the lower level is now integrated, thereby expanding the home’s size by at least 30%. New windows and doors were installed to frame views of the woods and improve indoor natural light, with the side benefit of improved insulation. Finally, the cosmetic changes: the whole house has new finishes, cabinets, plumbing fixtures and equipment; a new heating system and exterior siding were installed. The remodeled house is now truly a cozy Treehouse.