Drywall and plaster are common materials used to create smooth interior walls and ceilings, but they differ significantly in composition, installation, and performance characteristics.
At its core, drywall is a panel made from gypsum plaster sandwiched between two sheets of paper, while plaster is a wet mixture applied in multiple coats directly onto a lath base.
Understanding the distinctions between these two materials is crucial when considering historical preservation, renovation, or new construction projects.
Key Differences: Drywall vs. Plaster
Here's a quick look at the main differences:
| Feature | Drywall | Plaster |
|---|---|---|
| Material | Gypsum board with paper facing | Mix of lime or gypsum, sand, and water |
| Installation | Screwed/nailed panels, taped/mudded joints | Applied wet in multiple coats over lath |
| Thickness | Typically 1/2" or 5/8" | Thicker, often 7/8" to 1" or more (multiple coats) |
| Drying Time | Joint compound dries in hours/days | Can take weeks to fully cure |
| Cost | Generally lower labor & material costs | Higher labor costs due to skilled application |
| Durability | Can be more susceptible to dents/moisture | Harder surface, more impact resistant |
| Repair | Easier for small holes, harder for large | Can be complex, requires matching textures |
| Aesthetics | Standard smooth finish | Can achieve textured, curved, or ornate finishes |
| Performance | Standard sound/air barrier | Better sound and air barrier (due to thickness) |
Let's delve deeper into some of these points.
Material and Application
Drywall (also known as gypsum board, plasterboard, or sheetrock) arrives on-site as pre-fabricated panels. These panels are attached directly to wall studs or ceiling joists using screws or nails. The seams between panels are then covered with joint tape and multiple layers of joint compound (mud), which are sanded smooth to create a seamless surface ready for priming and painting.
Plaster, conversely, starts as a dry powder mixed with water to create a wet slurry. This mixture is applied in layers (typically a scratch coat, brown coat, and finish coat) over a substrate called lath. Historically, lath was thin strips of wood, but modern plaster systems often use metal mesh (expanded metal lath) or special gypsum lath boards. The application is a highly skilled trade, involving troweling the material smooth.
Thickness and Performance Benefits
One significant difference lies in the thickness of the finished wall.
Due to the number of coats and the underlying lath, 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, contributing to better acoustic privacy compared to standard drywall installations.
- Air Barrier: A thicker, solid mass with fewer seams helps prevent air leakage.
- Sound Barrier: Mass is a primary factor in blocking sound transmission. Thicker plaster walls inherently offer superior sound insulation.
Durability and Repair
Plaster generally cures into a very hard, solid surface that is more resistant to dents and impacts than drywall. This is why older homes with plaster walls often show less damage from daily wear and tear than homes with drywall built around the same time.
- Drywall Repair: Small holes in drywall are relatively easy to patch with joint compound or patching kits. However, repairing large sections or complex damage can be more challenging and may require replacing entire panels.
- Plaster Repair: Repairing plaster can be more complex. While minor cracks can be patched, larger repairs often require the application of new plaster layers and matching the existing texture, which typically requires a skilled plasterer.
Cost and Time
Generally, drywall is the more cost-effective option today for new construction and standard renovations. The material is less expensive per square foot, and installation is faster and requires less specialized labor than traditional plastering.
Plaster requires more labor time due to the multiple coats and curing periods between applications. The skilled nature of the work also contributes to higher labor costs.
Aesthetics
Both materials can provide a smooth, paintable surface. However, plaster offers greater versatility in creating custom textures, curved walls, and decorative finishes. Drywall can also be textured, but achieving the depth and variety possible with plaster is more difficult.
Choosing between drywall and plaster depends on factors like budget, desired performance (soundproofing, air sealing), historical accuracy (for older homes), and the desired aesthetic.
