What distinguishes drywall from plaster?

When constructing or renovating a home, most people focus on features like granite countertops, the overall square footage, or the number of windows. Often, the interior walls, an essential part of the home, are overlooked.

Interior walls aren't usually given much thought unless there's an issue or you move into a smaller space. However, they serve vital functions such as providing privacy, separation, and even acting as sound barriers, insulators, and offering enhanced fire resistance.

Plaster and drywall are two of the most common materials used for interior walls. Plaster, dating back to ancient civilizations, was originally made from lime, sand, animal hair, and water [source: MacDonald]. Egyptian tombs, like that of Queen Nefertari, feature intricate paintings on the plaster walls [source: Getty Conservation Institute]. The Romans are also known for decorating their homes with fresco artwork, where pigments are applied to wet plaster [source: The Metropolitan Museum of Art].

Gypsum-based plasters, which offer a quicker drying time compared to lime-based plasters, became a popular alternative [source: MacDonald]. This innovation helped speed up the construction process.

As technology progressed, drywall became both more durable and more accessible. By the 1950s, it had become the preferred choice for interior walls [source: Barber]. Today, drywall is found in the majority of modern homes.

In this article, we will examine the composition, pros, and cons of both plaster and drywall as materials for interior walls.

Let's start by looking at plaster.

Inside Plaster

Gypsum plaster is the most widely used type of plaster for interior walls. The typical process for creating plaster walls involves three coats. Initially, lath must be attached to the framing. Traditionally, this lath was made from wood strips, but nowadays metal or plasterboard are often used. The lath provides a surface for the wet plaster to adhere to.

Once the lath is secure, the plaster compound is mixed. Usually, this compound comes in a dry form and requires water to be added. While this step seems simple, achieving the correct consistency requires a certain level of skill and experience [source: Nash]. Afterward, the first coat of plaster is applied, scratched, and left to dry. This is followed by the second coat, or brown coat, and finally, a finishing layer is added to complete the wall.

Because of the multiple layers and lathing process, a plaster wall is generally thicker than drywall. This added thickness enhances its ability to act as a barrier for air [source: Heberle and Scutella]. It also helps with soundproofing between rooms. When installed properly, plaster can provide a sturdier wall that is less likely to buckle or break. Additionally, since plaster is malleable when applied, it works well for curved or irregular surfaces. The gypsum in plaster also contains a high water content, which imparts fire-resistant properties to the walls.

Despite its benefits, plaster has become less popular among homeowners today. Let's explore why this might be. For one, the plastering process is labor-intensive, which increases costs. The application and drying times also make plastering a time-consuming task. While plaster is durable, it can crack over time due to the building settling or improper installation. Some cracks can be repaired using plaster or a setting-type compound, but others may require more extensive structural repairs.

These challenges might explain why many homeowners and remodelers are now choosing drywall instead. Let's take a deeper look at this alternative interior wall material.

Inside Drywall

For standard gypsum drywall, calcined gypsum is mixed with water and sometimes additives to form the core material [source: Gypsum Association]. This thick mixture is then compressed between two layers of paper and dried. The front layer of paper is smooth and strong, while the back layer is rougher in texture [source: Ferguson].

The process of installing drywall is much faster than plastering. The boards are cut to fit the wall's shape and then secured to the house's framing. After the boards are in place, corner bead is attached to the edges to create sharp corners. Next, the joints and corners are taped with either paper or fiberglass-mesh tape, and joint compound is applied in three layers. After each layer dries, the wall is sanded to smooth it out. Once the third layer has dried, the wall is ready to be painted.

Drywall has clear advantages over plaster. For one, the installation process requires significantly less time and labor, which often means a lower cost. Additionally, drywall is effective at reducing noise and offers fire-resistant qualities due to the water content in the boards.

Although drywall offers many benefits as an interior wall material, it’s not without its drawbacks. Drywall can be damaged by settling of the building or accidental impacts. A common issue is nail or screw pops, where the fastener heads create visible bulges or protrude through the drywall.

Another downside is that gypsum drywall is prone to water damage if exposed to high moisture levels over extended periods [source: Gypsum Association]. However, there are specialty drywall boards available that include additives for better water resistance.

In addition to water sensitivity, gypsum drywall can also suffer from mold growth. To help reduce the risk of mold, newer gypsum drywall boards are being made without paper.

Whether you opt for the flexibility of drywall or the classic appeal of plaster, interior walls play a crucial role in defining the look, flow, and ambiance of your home. Understanding the pros and cons of both plaster and drywall will help you select the best option for your needs and lifestyle.