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.

It doesn’t matter which way you lay drywall, and you can choose to install it horizontally or vertically depending on the size of the wall and how tall the ceiling is. It’s easier to lay drywall sheets vertically if you have a taller ceiling, but laying sheets horizontally makes it easier to apply joint compound.

If you only have tiny holes in your drywall (for example, dents or nail marks), you probably won’t need a patch kit. Instead, you can plug the hole with a small amount of spackle. Once the spackle dries, you can sand the area and paint over it—just like you would in the steps outlined above.

You can plaster over regular drywall, but it's essential to prepare the surface properly. Before plastering, the drywall should be clean, free of dust, and any loose or peeling paint should be removed. Applying a primer specifically designed for plastering can improve adhesion. Some professionals recommend applying a base coat of plaster or joint compound to create a better surface for the plaster to adhere to. Proper preparation ensures a smooth and durable plaster finish over regular drywall.