What is the difference between drywall and plaster?

Inside Plaster

The most common form of plaster for interior walls is gypsum plaster. Plaster walls are generally created through a three-coat process. To begin, lath must be secured to the framing. Historically, lath has been made of wood strips, but more recently metal or plasterboard have come into use. The lath gives the gooey plaster something to hold onto.

After the lath is in place, the plaster compound must be mixed. The compound usually comes dry and must be mixed with water. While this step may sound fairly easy, a certain amount of skill and experience is needed to get the right consistency [source: Nash]. Then, the plaster can finally be applied to the wall. The first coat of plaster is applied, scratched and left to dry. It is followed by the second coat, or brown coat, and then the wall is finished off with a final layer.

Due to the number of coats and lathing, a plaster wall tends to be thicker than a drywall wall, which can create a greater air barrier [source: Heberle and Scutella]. This thickness also creates a good sound barrier between rooms. If the lathing and framing are done well, plaster can provide a much more rigid wall leading to reduced likelihood of buckling or breaking. Since plaster is not a solid when it's applied to the wall, it can be a good choice for curved or irregular surfaces. Finally, the gypsum within the plaster has a high water content, which gives the walls fire-resistant qualities.

Even with these benefits, plaster has fallen out of favor with homeowners today. Let's look at some possibilities for why that might have happened. First, the plastering process is labor intensive, causing the price to rise. Plastering is also time-consuming -- in applying and drying time. In addition, while plaster is very durable, it can crack with the settling of the building or improper installation. Some of these cracks can be fixed with plaster or a setting-type compound, yet others require structural restoration.

These may be some of the reasons that homeowners and remodelers are now more likely to opt for the drywall. Let's take a closer look at this interior wall material.