You can drywall an unheated garage because the material handles cold temperatures perfectly well. There are no risks or downsides to installing drywall in a garage that is not heated, and the material stands up to moisture and other elements quite well. Drywall will protect your unheated garage's electric wires and cables and add fire protection. However, for effective bonding, you should install drywall at a temperature of 55 degrees Fahrenheit or higher.

You should do a little bit of sanding between adding coats of mud. Knock down any ridges or significantly imperfect areas through sanding, which should help you apply the next coat of mud smoothly. If your first coat of mud is pretty smooth after it dries, a quick sanding is all you’ll need. Don’t forget to wipe away any dust after each sanding process.

Whether to repair or replace water-damaged plaster depends on the scale of the damage. For small, limited areas, you can often perform a repair yourself. If you choose to paint over small patches, ensure the surface is completely dry and apply a coat of antifungal primer first to prevent mold growth. However, simply painting or plastering over the damage is only a temporary solution that doesn't address the core problem. For more extensive or long-term damage, the plaster may be compromised, and there is a risk of mold. In these cases, it is recommended to remove the damaged section of plasterboard and replace it. You may consider hiring a professional for the repair, and it's worth noting that water damage is often covered by home insurance.

If your home was built before the 1940s and was not remodeled in the past 50 or so years, you probably have plaster walls. Aside from assuming, there are some practical ways to tell if you have plaster walls, including the following: If you knock on the wall and it feels solid, not hollow, if you can’t insert a thumbtack easily, if there are cracks that look like spiderwebs, or if your home has curved, arched, or swirled walls, doorways, or window openings.

If you have an unfinished basement or attic, you could examine the backs of any finished walls to check, too.