Q. How important is it to repair plaster before repainting? Our ceilings have peeling paint that we’re pretty sure was caused by past water damage. Since the water problem is no longer an iss… ...

But decorative plaster ceiling elements were heavy, difficult to ship, and hard to install, and therefore exceedingly expensive and impractical. So America turned to technology to solve the problem.

For example, you can get these Ekena Millwork Oxford Corners for around $50 for four and pair them up with a pack of Ekena ...

Rob Robillard discusses surface preparation. Plus, the mystery behind the mildew. Get more home improvement advice at realestate.boston.com.

An alternative approach — and an especially good technique if both the plaster and the ceiling joists are sagging — is to screw 1-by-3 or 1-by-4 furring perpendicular to, and into, the joists.