Are Your Walls Plaster or Drywall?: How to Tell

When preparing to paint or remodel, you’ll want to know what you’re working with. If you’re not sure whether your walls are drywall or plaster, read on for tips on how to tell.

Ask their age: Plaster walls tend to be found in older homes. The first forms of drywall were patented in the early 1900s, but it wasn’t until the housing boom of the 1950s that drywall—that is, thin panels of gypsum-based plaster sandwiched between two stiff pieces of paper—began to take off, and over the next few decades it became the industry standard. It’s not impossible that a newer, custom-built house might have plaster walls: some people prefer the texture and solidity of plaster, but the plastering process is several times as costly and can take weeks to fully dry.

Make some noise: Plaster is thicker and denser than drywall, making it substantially more soundproof. Knocking on a plaster wall will produce a dull thud and feel almost rocklike to the hand, like a drum filled with cement. Drywall will sound hollow, and you shouldn’t knock too hard: it’s more fragile than plaster, such that another test is to press a pushpin into an inconspicuous area. If it slides right in, it’s likely drywall.

Look inside: Unscrew an air vent or an electrical outlet cover, give a loud yell to scare away any flying squirrels that might be in there, and peer into the depths of your wall. Drywall will typically be half an inch thick, with paint applied directly to its surface, and you may be able to spy the backing paper. If, however, you see wood slats (called lath) or wire mesh supporting a thick, possibly crumbly looking substance, it’s plaster. You might even find a combination of the two: veneer plaster supports a thinner layer of plaster with drywall-like gypsum boards.