A Hybrid Approach to Lime Plaster
Drywall backing speeds the way to a textured, durable, old-world finish
Synopsis: While drywall has replaced plaster as the go-to material for walls and ceilings, it does not replace the look, feel, and durability of hand-applied plaster. Ace McArleton describes his approach to plastering, which involves using drywall as a base (primed with sand and glue) for lime plaster. The article describes the proportions of lime, sand, and water used to achieve a durable plaster that will trowel on easily, and then walks through the process of taping the walls followed by different techniques for using trowels to apply plaster to the field, around trim, and over outside corners.
Traditional plastering is a slow, laborious process, so it’s no wonder that when drywall came on the scene, it quickly replaced plaster as the go-to material for walls and ceilings in American homes.
But while drywall replaced plaster in function, it doesn’t replicate the look, feel, and durability of hand-applied plaster. Unlike drywall, plaster is a truly custom finish that can be sculpted and troweled to any number of desired shapes and textures. One of my favorite types is lime plaster—a strong, environmentally friendly, beautiful finish that has been around for millennia.
Made of a mix of sand, lime, and water, lime plaster has a high index of refraction, giving surfaces a warm glow that subtly changes color and tone as the sun shifts. The textures created by the sand and the plasterer’s trowel work can add even more dimensions of interest.
By contrast, the flat, smooth finish that drywall is meant to achieve in much of the United States is, by design, one-dimensional. When texture is added, it often just mimics traditional plasters.
Still, we like drywall. It’s a key component of our hybrid plastering approach, which takes advantage of some of drywall’s efficiency, availability, and strength, and melds it with the beauty of true lime plaster. Depending on the details, complexity, and size of the project, this method of plastering runs from $5 to $9 per sq. ft. This approach is more labor intensive than standard drywalling, but not nearly so laborious and costly as a standard three-coat plastering process.
Drywall replaces lath
Drywall provides a solid base for lime plaster, and goes up faster than the wood lath of the recent past. The drywall is hung in standard fashion, but it doesn’t get taped, so we don’t worry as much about the number of seams and can use shorter drywall panels, which makes it easier to estimate and hang.
Typically we use standard drywall, which is designed to tolerate wetting from drywall compound and water-based paint, and tolerates wetting from lime plaster much the same. We prime the drywall with a mixture of sand and Elmer’s Glue-All (a PVA glue, which is similar to PVA-based primers). We roll and brush this slurry on just like paint to give the wall some tooth to help hold the plaster. We haven’t had issues with lime plaster failing on bare drywall, but taking this extra step is a cheap insurance policy, and it dries quickly.
On this job, the drywall contractor installed blueboard, which is made to serve as a base for veneer gypsum plasters. We’ve found that the extra expense of blueboard isn’t necessary, but it doesn’t hurt either.
For more on Lime Plaster:
- VIDEO: Lime-Plaster Installation Over Drywall
- A Short Guide to Lime-Plaster Trowels
- Add Color to Lime-Plaster Walls
- From Rock to Dust to Rock Again: An In-Depth Look at Hydrated Lime
- Lime-Plaster Transformation: A Slideshow
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