Are Plaster Walls Soundproof? 4 Things To Know

Sharad Dominic

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When you’re buying a home, one of the things you’d want to know is how soundproof your walls are. You wouldn’t want too much noise from the outside or next-door neighbors to disturb your activities. If you have plaster walls, you don’t have to worry too much about soundproofing.

Plaster walls are not completely soundproof but they provide excellent soundproofing when compared to the popular drywall construction. Plaster walls are made up of layers, so they act as a decent sound barrier.

Are Plaster Walls Soundproof

This article goes over the difference between plaster walls and plasterboard, their soundproofing quality, and how to avoid noise transfer more than just soundproof walls.

Also read: How to Soundproof a Plasterboard Wall (3 Steps)

Are Plaster Walls Soundproof Actually?

Plaster walls are soundproof. When you compare plaster walls with other soundproofing materials, they might not come out on top. However, they provide a thick enough barrier to muffle sound coming from another room or house. 

Below are 4 things to know about plaster walls:

1. Plaster Walls Are Different From Plasterboard

There can be some confusion regarding the terms plaster wall and plasterboard walls. These are two different types of wall construction.

Plasterboard is synonymous with:

  • Drywall
  • Gypsum board
  • Sheetrock
  • Plasterboard

These terms are the same but can differ in usage depending on the region.

Plasterboard/Drywall

The more common term in the U.S. is “drywall” construction. Here, compressed plaster, gypsum, or other materials are covered with thick sheets of paper and used to create panels of plasterboard or drywall.

These panels are then directly nailed or screwed onto the wall studs to quickly create walls and partitions.

Drywall construction is prevalent because it is very economical and is quick and easy to install.

Plaster Walls

Plaster walls have been a less common wall construction method since the advent of drywall.

For this type of construction, wooden lathes (thinner strips of wood) are laid perpendicularly over the wall studs. Plaster is then applied directly to the lathes to fill out the gaps. When this is dry, two or more layers of additional plaster are applied.

Sometimes, a steel mesh is laid on the wall studs instead of using wooden lathes.

The finished wall can be smooth or textured, depending on your preference. This wall construction method provides a much denser and thicker barrier between rooms or areas of your home.

Plaster walls cost three times as much as plasterboard or drywall. This is because it is much more labor-intensive to construct and requires specialized labor.

2. Plaster Walls Provide Good Soundproofing

As previously mentioned, plaster walls are made of several layers of plaster laid over lathes or a steel mesh attached to the wall studs. This type of wall is much denser and thicker, meaning more mass to dampen sounds and noise traveling from one room to another.

3. Plaster Walls Are More Soundproof Than Drywall

Sound Transmission Class (STC) rating measures how much a material reduces or dampens airborne noise. The higher the number, the more effective the material is at soundproofing.

STC rating goes from 25 (normal speech can be heard) to 65 (completely soundproof).

Plaster walls on wooden lathes provide an STC of around 52. At an STC rating of 45, loud speech can’t be heard. When you have an STC rating of 50, loud music can barely be heard. So with plaster walls, you can be sure that your neighbor’s loud TV won’t bother you.

Drywall on 3 ⅝” metal studs with ⅝” gypsum boards has an STC rating of 38-40. With this rating, loud speech can sound like a hum.

Drywall, especially without batt insulation between the boards, doesn’t provide ample soundproofing because the airspace provides a good conductor for sounds. The vibrations of airborne sound that hit one side of the wall are easily transmitted through the air and to the other side.

The air space and two flat surfaces also provide ample area for sounds to bounce and reflect, even amplifying the volume of sound and noise.

4. Soundproofing Walls May Not Solve All Noise Transfer

Noise and sounds can leak through holes, cracks, and other openings in walls like water. So adding batten to drywall and patching cracks in plaster walls may not be enough to solve a soundproofing issue.

Sound can still come through other openings like windows and doors. Noise can also transfer through other surfaces like the floor and the ceiling.

Here are some ways you can dampen the sound transfer in your home:

  • Use double pane windows. These windows block out sound much better than just single-pane windows.
  • Soundproof your windows. You can use acoustic sealants or insulation tape to seal your window frame where it meets the sill. You can also add an acrylic sheet to the interior of your windows to provide an extra barrier against noise.
  • Add thick curtains. You can also add thick curtains to help dampen the noise coming from outside. Amazon.com has these NICETOWN Soundproof Insulated Blackout Curtains that will help dampen noise and block out 85%-99% of light, and transfer heat and cold from outside.
  • Soundproof your door frames. This means applying soundproofing methods like rubber, weatherstripping, or door gaskets, to plug up gaps where sound might pass through. This Holikme Door Draft Stopper (available on Amazon.com) works by sealing up the gap that exists under all doors. It helps block out noise from leaking through the space and stops any drafts from blowing through.
  • Soften surfaces around your home. Hard surfaces provide the perfect way for noises to reflect, bounce, and echo. To help lessen this, you can add carpets or rugs to your floor. More furniture in a room also helps to diffuse and absorb traveling sounds.
  • Use acoustic panels and boards. You can also consider using acoustic panels and boards and installing them on your walls, though they may not fit the look of many of the areas in your home. This Acoustic Wall Art Panel from Amazon.com is perfect for you if you want to add some soundproofing to your wall. It looks classy compared to your average soundproofing panel or foam.

Final Thoughts

Plaster walls provide good soundproofing for your home. Their STC rating of 52 means that most loud noises will barely be heard through a plaster wall, including loud music.

Plaster walls have much better soundproofing capabilities than the more popular drywall construction, with an STC rating of 38-40.

Walls aren’t the only transmitters of sound. Soundproofing windows, doors, floors, and ceilings can also help with noise issues.

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