Wall Work: Tips and Tricks for Working with Plaster Walls

By Mark Clement

Tips and tricks for working with plaster walls—from pulling it down to patching it up.

If you live in a house built before 1940, you almost certainly have plaster walls and ceilings.

At its best plaster makes surfaces uber-hard and sound-deadeningly substantial. At its worst, it’s a brittle wall-covering that’s practically looking for a way to jump off the wall.

Good installation or bad, however, the presence of plaster signifies several things beyond the age of the structure, notably the home probably:

• doesn’t have insulation
• does have lead paint
• doesn’t have many straight lines for easy trim layout.

So whether you’re adding trim or doing a gut-and-rehab on an old house, here’s a few tricks for working with plaster. But first (there’s always a “but first” with me  isn’t there?), here’s a little information on what plaster is and why we don’t use it much anymore.

Anatomy of a Plaster Surface

While plaster can be applied directly to block walls it is often applied over a layer of wood lath (2-inch, rough-sawn strips nailed with the world’s sharpest nails). Lath is nailed perpendicular to wood studs or over 1-by fastened to the block.

A proper plaster coat consists of three parts: a scratch coat, a brown coat and a skim coat. In more modest homes, the brown coat might be skimped on or otherwise skipped, which leaves the plaster finish thin and easily damaged. Houses in this condition may well have wallpaper, which was used as decoration as much as to hold the plaster together. (Our house had wall-paper—I’m not kidding—on the ceilings.)

Brief History

The reason drywall is called “dry” is that plaster is applied wet. Drastically oversimplifying the art, it’s like applying increasingly fine grades of site-mixed mortar to the wall surface.

The reason for the switch from plaster to drywall in the 1940s was a combination of the product itself (drywall was invented in the 1890s), a lack of labor (due to the War), and a demand for high-speed installation in homes and factories, again due to the War effort.

Another big reason the industry never shifted back to plaster—aside from the fact that plaster is much more labor-intensive and expensive to install than drywall—was the immediate need to house soldiers returning en masse from the War.

Lead Paint

The first thing to know about plaster is that you have to follow the EPA’s new lead paint regulations when you disturb the paint that’s on it. Called RRP for Renovation, Repair and Painting, lead-safe remodeling practices are the law. And, when you find out what the lead dust can do to your kids, you’ll want to make sure you follow the new rules that center around containing and cleaning lead dust from disruptive activities like demolition, sanding, and paint removal. What’s more, if you’re hiring a remodeler, it’s required by law that they must have passed a Lead Safety Certification course to work with lead paint-coated materials. OK, now on to the good stuff.

Prying the lath from behind is the most effective way I’ve found for full scale plaster and lath tear-down. Always suit up with eye protection, gloves, long-sleeves, and a mask or respirator- you’ll really want them because the material is coming at you. (Note: I let dust clear before taking this photo and took the gear off; I got so wound up in getting the photos I forgot to put it back on.)

The first step to removal in a plaster demo project is to strip all the mouldings.

Demolition

For many homes, the best thing to do with plaster is to remove it. With the walls open, you have the opportunity to insulate and update old plumbing and wiring (pipe and wire is cheapest while walls are open). For a wood-framed house this means dropping the plaster and making the upgrades. Once you close it all back in, if you have a block house, you’ll end up with super-deep window sills and exterior door jambs, which are awesome.

While the walls are open, the time is right for sealing the building envelope in areas you might not think of, such as along the ceiling joists

Plaster and lath pile up fast in a knotty web of major mess. We usually bag up the debris and toss it out a window rather than dragging it through a finished home. Protecting finished floors from this chaos is critical.