Press a hand flat against one of your walls. If it feels hard and cool, more like stone than cardboard, there’s a decent chance it isn’t drywall. Some homes have veneer plaster instead, which is a thin coat of hard plaster troweled over a special gypsum board.
From across the room, it can pass for drywall. Get close, though, and it has a harder, hand-troweled look. Knowing which one you’ve got matters most on the day a crack shows up.
So What Is It, Exactly?
It starts with a gypsum board that’s often called blue board. A plasterer trowels one or two thin coats of plaster over it.
That coat is only a small fraction of an inch thick, but it still cures very hard. You end up with a smooth wall and no visible seams. It can also take a light texture.
What Causes Cracks in These Walls
Veneer plaster is strong. The National Park Service notes that a two-coat system is rated at 1,500 psi and can handle normal building movement. So if you do spot a crack, it may point to something behind the surface.
One place cracks can show up is along the seams between boards. A nail holding a board can rust or work loose, or the framing can shift a bit. Then a thin line shows up right where the seam is. In older Long Branch homes, from the North End to Branchport, that’s worth keeping an eye on.
Water is the bigger worry. A leak at a window, the roof, or an outside wall can soak the board behind the plaster. Once that happens, the surface may bubble, stain, or start pulling away.
When It’s Time to Call Someone
A thin crack in a wall that’s dry and solid is often just cosmetic. These signs are a different story:
- Brown or yellow stains that come back after you paint
- Soft spots that give a little when you press
- Cracks that keep getting wider over a few months
- Plaster that bulges, or sounds loose when you tap it
See any of those? Find the water first, because a patch on a wet wall won’t hold. CMB Jersey Shore Stucco and EIFS Repair & Installation handles veneer plaster repair in Long Branch and has worked on walls across the Jersey Shore since 1985. Before mixing a patch, the crew checks flashing and trim for leaks.
How to Tell It Apart From Drywall
Not sure what’s on your walls in the first place? You won’t need tools for this.
Pick a spot inside a closet and press a fingernail into the wall. Drywall dents pretty easily, while hard plaster barely marks. Next, hold a flashlight flat against the wall and look down its length. Drywall may show faint seams or little screw bumps.
One more. Turn off the power, take off an outlet cover, and look at the cut edge. You may see a thin, hard layer sitting on top of the board.
If two of those point to plaster, you likely have a plaster wall, either veneer or traditional.
Getting the Patch to Disappear
Filling a crack is the easy part. Making the patch vanish takes skill, since the new plaster has to match both the texture and the sheen around it.
Drying time is worth asking about, too. USG says its Diamond Veneer Finish can dry in as little as 24 hours, which allows painting the next day. Your room and the weather still play a part, so check with your plasterer before you open a can of paint.
A Few Habits That Help
- Run a dehumidifier in damp months so indoor air stays steady
- Fix roof, window, and plumbing leaks right away, not next season
- Hang heavy mirrors and shelves with anchors made for plaster
- After a big storm, look for new cracks near doors and windows
- Snap a photo of any crack so you have something to compare later
Plaster walls can last for decades with a little care. Catch problems early and the repairs stay small.
Got cracks or stains on your plaster walls and not sure what they mean? Call CMB at (732) 400-4020 and talk it through.
