A leak? Oh, no! What a mess. After you get the resultant dampness out of the way, treat to prevent mold, and repair the area where the leak occurred, you’re probably going to need to repaint. If you’ve replaced wood, drywall, or other surface materials, you can prep as usual and get down to business.
In other situations, say you’ve replaced the outer materials and the insulation, but the inside materials are still useable (and have been thoroughly cleaned and dried) you may need to do a little extra prep work before pulling out the paint brush.
First, make absolutely sure that the area is completely dry. Scuff the surface with fine grain sand paper. This will not only give paint something to grab onto but it will also show you if the surface is damaged more seriously than assumed. It the material begins to crumble or chip away, you would be well advised to replace that section.
If the surface is useable but badly stained and the stains are not eradicated after cleaning, you will need to apply a stain blocking primer (such as Kilz) before painting. Apply and allow to dry as directed. It’s actually a good idea to allow the primer to dry for at least an additional twenty-four hours (after the suggested drying time) to make sure it has cured properly. This way, you will be able to see if it has actually covered the stain sufficiently before you begin painting. Otherwise, you may complete your painting only to find that the stain is going to show.
Still, you may need to apply a second coat of paint, and it’s a good idea to use mold/mildew resistant formulas. Read labels carefully as some contain harmful ingredients. As always, ventilate the area sufficiently when using paint, primer or any product that disperses fumes.