Charlotte Worthy, a New York architect, knows the struggle of restoring original wood floors all too well. Overseeing the restoration of an early 1900s townhouse on the Upper West Side, Ms. Worthy discovered that the detailed marquetry borders in the public rooms could withstand no additional sanding. So she and her team designed new borders and decorative patterns that would look authentic, and Mr. Estrin and his crew of carpenters used the designs to construct and install new floors.

With a careful combination of white-oak wood grains, the updated flooring changes shade depending on how the light hits it. “The light that rakes in from the windows — and, to a lesser degree, from the light fixtures in the room — reacts differently depending on the angle of light and the direction of the grain,” Ms. Worthy said. “The wood looks darker where the light is being absorbed on the end-grain pieces, and lighter and reflective on areas along the grain.”

Of course, not all prewar renovations will require such sophisticated repairs, and there are less expensive options available, Mr. Estrin said. “One can simply replace the existing prewar flooring with a new prefabricated and pre-finished wood floor,” he said. “Quite often, these types of floors are easy to install and will end up being less costly than refurbishing an existing prewar floor — you’d just be losing a lot of charm and history by doing so.”

Ms. Worthy added: “If you are fortunate enough to acquire a project that involves restoration, you must prepare yourself for the ups and downs that any construction project will deliver. But in the end, you’ll be saving a part of the living history of architecture.”

For weekly email updates on residential real estate news, sign up here. Follow us on Twitter: @nytrealestate.