Homeowners often have difficulty distinguishing between plaster and drywall. Of course, this confusion is caused by the similar uses of these materials in constructing residential walls and ceilings. Luckily, several methods can be used to determine whether a surface is made from drywall or plaster.
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Homes constructed before 1950 commonly use plaster, while those built after 1960 typically use drywall. A knocking or pushpin test can be done to determine whether a surface is made from drywall or plaster. This can also be determined by inspecting cracks or looking behind surfaces.
If you’re unsure of how to distinguish between drywall and plaster, we’re going to explain all the different checks that can be used. From considering when your home was built to removing an electrical outlet, there are many methods that can be used!
Telling The Difference Between Drywall And Plaster
Many homeowners find it difficult to distinguish between drywall and plaster. Ultimately, this confusion stems from the comparable uses for these building materials. Before we explain how you can tell the difference between these materials, let’s take a brief look at each material.
Plaster, which is commonly used to coat and protect internal walls and ceilings, has been used for longer than drywall. Plaster can also be used for decorative moldings. Plaster is typically made from water and sand, with the addition of gypsum, cement, or lime.
Drywall is another widely used building material that is also used to cover and protect walls, ceilings, and framing. There are different types of drywall that can be used, which are all made from gypsum. Due to this, drywall is often referred to as gypsum board.
Due to the similarities between these materials and how they are used, many people have wondered how they can tell the difference between drywall and plaster. We’re going to break seven six ways you can tell whether a wall is made from drywall or plaster!
Method One: Consider A Home’s Construction
While the other methods we’ll discuss are more direct ways to determine what a wall or ceiling is made from, considering when a home was built can point you in the right direction. For homes constructed before the 1950s, plaster is the most common material. For homes constructed after the 1960s, interior walls will generally be made from drywall.
However, for buildings constructed between the 1950s and 60s, the walls may be plaster or drywall. This is due to the timeline of when drywall became widely used in residential construction. Luckily, one of the following methods can help you determine which material was used.
Method Two: Knock On Interior Surfaces
Not many homeowners know that they can determine whether a wall or ceiling is made from plaster or drywall by knocking on it. To do this, you’ll need to knock on different areas of an interior surface. The sound produced will differ between plaster and drywall.
When knocking on drywall, you’ll note a hollow sound. However, this sound tends to change when you reach a stud in the wall. However, with plaster, the sound will remain consistent regardless of where you knock the wall. In many regards, this is a simplified version of the pushpin test used by contractors.
Drywall
Knocking on drywall should produce a hollow or empty sound in some areas, while it may sound dense in others.
Drywall is attached to wall studs, which are vertical pieces of wood put together as a frame. You’ll hear a hollow sound when you knock on the part of the drywall that covers a space between the studs. The knock will sound dense when it lands on the part where a stud stands.
Plaster
Because a plaster wall is solid, knocking anywhere on it should produce a thick sound all the way through.
Method Three: Use The Pushpin Test
When professionals need to determine what an interior wall is made from, many will use a pushpin to do this. Essentially, a push pin can be pressed into an interior wall to determine which material it is. If the pushpin easily penetrates an interior wall, it’s likely made from drywall. With plaster walls, homeowners will struggle to insert the pushpin.
If you determine that it was plaster, you also have to check for asbestos as it was commonly used together. Asbestos has to be removed with care as it can be quite dangerous.
Drywall
The pushpin or thumbtack will easily go through drywall.
Sharp objects can penetrate drywall because it’s made of a soft mineral called gypsum sandwiched between two layers of paper.
Plaster
A plaster wall will resist the pushpin or thumbtack. You’ll need a hammer and nails if you want to penetrate plaster.
Unlike drywall, plaster is hard. This is because it’s composed of either lime, gypsum, or cement, mixed with sand and water—a mixture that hardens as it dries.
Even though some plasters have gypsum, these types still harden when they dry due to the mixture’s natural reaction to water.
Method Four: Inspect Walls For Damage
If you don’t have a pushpin handy, you can even inspect your interior walls for damage. In fact, any damage you find can help you conclude what the wall is made from. With drywall, cracks are typically only found in smaller areas, typically where a joint compound has been used to conceal the drywall’s seams.
However, with walls constructed from plaster, cracks can be found spreading in many different directions. The cracks that form in plaster are more dominant than those formed in drywall, making it easy to tell them apart by inspecting this damage. If you don’t spot any cracks, you can try inspecting any unfished areas of the home.
Drywall
Drywalls should have little to no cracks. If there are any cracks, they’re usually thin hair-like lines that run on corners or small areas of the drywall.
Weak points, such as joints and the areas where two pieces of drywall meet, as well as high-stress areas, such as the corners of windows or doors, are prone to cracking. The flat surface of the drywall, on the other hand, is often free from cracks.
Plaster
The cracks on a plaster wall are very noticeable and often described as spider web-like lines that go in all directions.
Between the two, plaster is more prone to cracking than drywall. Flaking paint may also be present around cracks on a plaster wall.
Method Five: Inspect Any Unfinished Areas
Many homeowners decide to leave areas like basements and attics unfinished. In these instances, it is often possible for homeowners to see the backside of interior surfaces. Of course, this makes it easy to determine the material that was used for construction.
With plaster walls, the backside will be covered in many wooden panels or laths – which is why an even knocking sound results. With drywall, however, you’ll be able to notice vertical studs that are spaced further apart. Naturally, this is the reason drywall produces different sounds depending on where you knock.
Drywall
For drywall, you’ll notice that the wall is layered with paper. You can also check the wirings behind the drywall. They should be safely enclosed in an electric box.
Plaster
There should be a solid layer of plaster. What’s more, the wirings behind a plaster wall are loose. You may also be able to see laths or thin wood strips behind it.
Remember that no paper should be in sight if the wall is plastered.
Method Six: Look Behind Interior Walls
If there aren’t any unfinished areas in a home, there’s another way to look behind interior walls. The easiest way to do this is by removing an electrical socket from the wall. Of course, this will allow you to see a cross-section of the material used to construct the wall.
If a wall is made from plaster, homeowners will be able to spot the plaster layers in this cross-section. You may even see some plaster between the wooden panels. If you notice loose wiring in the cross-section, the wall is certainly made from plaster.
With drywall, however, there will be a layer of paper that is visible. Furthermore, wiring behind drywall cannot be loose like plaster. If you notice wires that are covered using an electrical box, the interior walls are made from drywall.
Method Seven: Check the Attic or Basement
Some attics and basements are left semi-furnished, exposing the opposite side of the wall. Because of this, you can see the materials used to support the wall. You can also check the wirings and see whether they’re enclosed in an electric box or left loose.
Take note that only interior walls can be covered with drywall or plaster. Exterior walls are insulated with different materials. So if you want to know if your walls are finished with drywall or plaster, inspect the interior walls, such as the attic’s floor or the basement’s ceiling.
Drywall
Drywall is supported by wall studs. The opposite side of the drywall, which is made of paper, should also be visible through the spaces between the studs.
Plaster
Behind a plaster wall, you’ll see laths attached to studs. There should also be excess plaster that had seeped through and hardened in the gaps between the laths if a wall was plastered. Those excess plasters are called plaster keys.
Method 8: Determine When the Structure Was Built
If you’re trying to inspect your own home, you probably know when it was first built. The age of the structure can help identify if its interior walls are made of drywall or plaster.
Knowing the age of a structure may be the fastest way to identify drywalls and plaster walls, but it’s also the least reliable—renovations and wall repairs could have taken place through the years.
Drywall
Wall structures built in the 1960s and years later are likely covered with drywall.
Drywall’s prototype was patented in 1894 but only became the preferred choice for wall finishes around the 60s. Drywall’s leap in popularity in those years suggests that most structures built years later have drywalls.
Plaster
There’s a high probability that plaster was used for wall structures built before World War II or years earlier than 1940.
Plaster has been around longer than drywall and it took some years after World War II before drywall became widely used in the homebuilding industry. Therefore, it’s likely that plaster was used in walls through the 1940s and earlier.
It’s worth noting that structures built in between the years of plaster’s reign and drywall’s growing popularity (1945-1960) could have walls made with either material.
Conclusion
There are numerous methods that can be used to determine whether plaster or drywall was used to construct a surface. Telling these materials apart can be as simple as considering when your home was built, knocking on surfaces, and inspecting surface cracks. However, it’s also possible to uninstall an electrical outlet or use a pushpin to determine this.
We have discussed how to plaster a ceiling here.
Drywall is softer than plaster—this is the most noticeable difference between the two, and the pushpin test will tell you whether your wall is plaster or drywall.
Other than the pushpin test, knocking on the wall and identifying the materials used in its installation are also reliable ways to identify drywall and plaster.
Sources:
https://www.picturehangsolutions.com/blogs/info/5-ways-to-differentiate-plaster-wall-and-drywall
6 Types of Drywall and How They’re Used
https://www.aboutmechanics.com/what-are-the-different-uses-of-plaster.htm
