LISTEN PT 1...
Retrofitting older buildings for better performance may include the removal of trim, woodwork, cabinetry and other finish elements. The skills that went into creating many of these pieces are not so easily replaced - take care to gently remove these layers and plan to reuse as much as you can.
If materials have deteriorated to the point where they can't be preserved, consider the option of recreating moldings and trim with contractors or manufacturers who specialize in this type of woodwork and finishing. The Tools & Resources section at the end of this module has a list of educational institutions that teach restoration carpentry techniques in Canada and the United States.
LISTEN PT 2...
According to Canada's Historic Places "Standards and Guidelines for the Conservation of Historic Places in Canada", there are 3 main approaches to take when working on heritage buildings: