Plaster Maintenance in Your Old Home
Is plaster worth keeping? In short, yes! Plaster is a historic feature of old homes that was designed to last and is more durable than modern drywall, which entered the scene in the 1950s. If mixed and installed properly, plaster has a lot of great benefits. It is more resistant to dents and plaster walls and ceilings can last for centuries. It's also more energy-efficient, absorbs more noise and is more fire-resistant than drywall. Not to mention, it's one of the things that adds historic charm to your home.
So if you have some minor cracks or holes in your walls or ceilings, it's absolutely worth taking a closer look and seeing if you can repair the plaster. Here are some reasons your home may need plaster repair.
Reasons to Repair Plaster
- Settling: As the house settles or soil expands over time, it can cause sagging or cracks.
- Excess moisture or humidity: While plaster is resistant to humidity, the moisture can damage lath, which in turn won't hold the plaster in place.
- Window/Door replacement: The installation of new windows and doors can cause pressure on plaster. Also, if the new windows and doors are too lightweight, they may not support the weight of the plaster.
- Heat: The plaster surrounding a fireplace can crack as the chimney expands and contracts with heat.
- Improper installation: One of the biggest reasons plaster fails to last is improper or poor-quality installation. Depending on the severity, you might be able to repair the plaster, but you might need to have it redone.
If the cracks are minor, you can repair them on your own. But if there is significant damage from structural issues, moisture or improper installation, you should refer to a professional to assess and repair. Before we jump into how to repair minor cracks, holes or peeling paint in your plaster walls and ceilings, let's first go over what they're made of.
What Plaster Walls Are Made Of
Typical plaster walls and ceilings are made of plaster and lath. The lath - thin, unfinished wood strips - are attached to the studs horizontally with about a 3/8" (or about a finger-width) gap between each one. Then plaster - a mixture of powdered lime, sand, and fibers (often horsehair) - is applied, most commonly in three coats. The plaster oozes between the gaps in the lath and when it dries, it creates a dense, rock-hard coating that's nearly one inch thick.
How to Repair Cracks in Plaster
Plaster may be the old way of doing things, but you can use tools and materials that you'll find at your local hardware store to repair them. If you have larger cracks, cracks that seem to be expanding or they are due to structural movement, we recommend you have a professional assess the damage. If your cracks are smaller, keep reading!
Fine, hairline cracks can be filled easily with a patching material. If you have cracks that reopen with seasonal humidity change, you can repair them following the instructions below.
WHAT YOU'LL NEED
- Utility knife or 5-in-1 tool
- Shop vacuum
- Spray bottle or plaster bonding agent
- Drywall knife (6")
- Plaster or gyprock
- 150-grit sandpaper
INSTRUCTIONS
Prep for Repair
- First, you'll want to slice open the crack with a utility knife and remove any loose material, using your shop vac to clean it out. Be gentle and work slowly.
Apply Plaster & Sand
- Lightly wet the plaster with water using a spray bottle so that it does not dry out your patch too quickly. Alternately, you can use a plaster bonding agent.
- Mix your plaster and apply a thin layer over the crack, smoothing it over so there are no wrinkles or air bubbles. Let it dry completely.
- Add another layer of plaster and smooth it out so it's flush with the rest of the wall or ceiling. Let it dry completely.
- Using your 150-grit sandpaper, smooth the larger bumps and ridges
- Inspect the surface for any dips. If your repair needs a little more blending, apply a third layer. When it's completely dry, sand it again very lightly.
Clean
- Use your shop vacuum to clean up the dust and wipe the surface down with a dry cloth.
How to Repair Holes in Plaster Walls
If you have holes in your walls that are larger than 4 inches or any holes in your ceiling, we recommend consulting a professional. But if you have smaller holes that are less than four inches in diameter, you can repair them with 2 coats of plaster.
First, you'll apply a base coat using a trowel to fill the hole and then scrape it away below the level of the existing plaster. When that base coat sets (but is not fully dry), apply a second coat and smooth it over until you have a level surface. And voila, that's it!
How to Repair Peeling Paint on Plaster
Is the paint on your plaster walls peeling? This usually occurs when many layers of paint have been applied over the years. Older paints had calcium in it, which, when combined with plaster could cause it to peel over time.
To fix this problem, you'll need to remove the paint instead of painting over it yet again. You can use a wallpaper steamer and plaster knife to gently remove the older layers of paint. After you remove all the paint, wipe the walls down with a damp rag, trying not to get them too wet. Allow the plaster to dry for 24 hours before repainting.
Best of luck bringing the love back into your historic plaster walls!
