I am designing a home for a family in New Hampshire that will be of both conventional stick construction and some timber construction. The second floor framing will be 90% timber for the purpose of exposing the beams and deck for a nice ceiling treatment over the main floor.

Is there rules of thumb that could be applied to give the client a good sense of the excess cost of the timber frame floor as opposed to dimensional lumber and drywall or does a material take-off have to be done?