We have a bathroom vent that is covered by a thin metal screen. It vents directly into the attic. I want to cover it with drywall. The ceiling is plaster.
I need a piece of backer wood so the drywall can attach to something. This is what I did.
I basically screwed the wood to the attic side of the plaster ceiling. It actually goes across the screen frame.
Should I have attached the wood to the wood beams instead. Note: a couple of small pieces of plaster ceiling fell off into the bathroom because of the screws.
I already screwed in the drywall piece from the bathroom.
Best Answer
Using backer strips to hold on drywall patches is a standard repair technique. Often the screws holding the backer boards are inserted through sound plaster or plasterboard from the finished room side.
Your approach seems fairly sound, but I would add a few screws from the good side, being careful not to crack the plaster too much as you install. Since you seem to have real plaster, I would predrill the holes, although when screwing through drywall, it is not necessary.
Finally, are you making some arrangement for a real vent to the outside? Moisture vented to an attic space is simply wrong, leading to possible moisture damage and mold. Closing off the bad vent is a start, but not the full solution for the problem. As @JamesOlson points out in his comment, an openable window is adequate ventilation; but if there is none, some other exterior vent is needed.