QUESTION: I am redoing the walls and the sloping ceilings of my attic, where buttons were installed to hold the plaster in place and a skimcoat covers everything. About a third of the skimcoat has fallen off, most of it on the sloped ceiling. Can I redo that, or should I do something else?

ANSWER: The buttons (called ceiling buttons) can hold the plaster on forever, but the skimcoat failed because a bonding agent was not applied first. More skimcoat is likely to come off. So instead of trying to redo it, I suggest taking the whole mess down (at least on the sloping ceiling, where failure is more likely than on a vertical wall), and installing drywall plasterboard, with nail heads covered with joint compound and seams taped and compounded. A fancier and more expensive job would be Blueboard and a skimcoat.

QUESTION: My attic floor was insulated with 3 inches of fiberglass with a paper backing toward the occupied space. Later, 3½ inches of unbacked fiberglass was installed, bringing the insulation to within half an inch or so of the tops of the joists. I would like to add insulation, but some parts of the attic have a plywood floor. Can I put the insulation on top of the plywood?ANSWER: No, do not cover the plywood. Instead, take up the plywood and install 2 -by- 6s or 2 -by- 8s at right angles to the original joists, 16 to 24 inches on center. Install insulation between new joists, then put down the plywood. In places where there is no plywood, put insulation on the original insulation at right angles to the joists. Use Polywrap, 8 inches of insulation wrapped in perforated polyethylene, which is not a vapor barrier but allows easy movement over the insulation without injuring your hands from the fiberglass.