Preparation of drywall for painting?

Due to poor planning, the previous owners vented a dryer into a garage instead of the outdoors. (We have since corrected this problem and it vents outside now.) The ensuing moisture and condensation caused the paint to come away from the drywall on the garage ceiling. I have scraped the loose paint off and am down to bare drywall. Is there anything special I need to apply to the drywall before I paint?Preparation of drywall for painting?
Any dings or nail holes should be spackled and sanded smooth. Once you have a smooth finish (it doesn't have to be super smooth, as it is your garage!), paint the drywall with a primer paint. Check with a hardware store or Home Depot/Lowes on the best primer paint for a garage in your region. A lot depends on how cold it will get and the humidity levels. Once the primer is on and dry, top coat it with a paint again chosen for this application.





A paint used indoors is subjected to a much narrower range of temperatures and humidity than paint in a garage, at least in most parts of the US. So be sure you get quality products that will work in your region.Preparation of drywall for painting?
It depends. Dry wall tends to soak up paint. You could use Kilzs (hope I spelled that right) and it would help the paint show up quicker (especially on dark colors).
just good primer. but don't forget to wrap some insulation around the duct so it doesn't sweat.
a good primer
After priming your wall, use a paint that will prevent moisture or after making sure that there is a good seal at the exit point, try using Thompson's water seal and see if this does the trick.
Just primer
if the humidity 60 or below i think it would be safe to paint after 24to48hrs
When you scraped the loose paint, did the paper backing from the drywall come off too? If so, you need to repair the ceiling before you paint.





If you just need to paint, any good primer should do, but be sure to do the entire ceiling, or you are likely to have a noticeable difference in holdout (you'll see the difference between old and new right through the topcoat of paint).





If there's any water staining, use a stain-blocking primer like Kilz - there are other brands as well. Usually these require two coats for stain-blocking applications.