DIY Plaster Repair Mistakes to Avoid

A homeowner should never put off plaster repair when they notice even the smallest cracks, chips, or areas of spalling along a home's plaster ceilings, walls, or trim work. If left unchecked, small cracks in plaster can get much more extensive in a short amount of time. Surface damage to plaster can also indicate that the framework of the house itself needs certain structural repairs.

The most common mistakes to avoid when repairing plaster in your home include patching over materials that should be outright removed and replaced, not removing plaster surrounding damaged areas, and failing to examine the home's framework behind broken or cracked plaster for water damage or needed structural repairs.

If you own a home with plaster walls, ceiling, trim, or decorative cornices, note some common DIY plaster wall repair and ceiling repair mistakes to avoid. Understanding a few common mistakes made while repairing plaster will ensure you know when this repair work is outside your area of expertise and when it's time to call an expert who knows how to repair plaster walls and ceilings properly!

Filling Without Patching

There is a difference between filling plaster cracks and outright patching plaster. Filling a break, as the phrase implies, involves merely pressing plaster or joint compound into a damaged area of a wall or ceiling, and then sanding down this material until it's smooth.

Typically the repair is then quickly repainted. Note that this simple filling is only appropriate for small cracks and chips, where the base of the original plaster is not exposed; this is not how to fix plaster walls suffering more severe damage!

Patching plaster walls or ceilings refers to replacing missing chunks of original plaster with sections of new plaster compound. When you patch plaster, you add this new material all the way to the lath or wire mesh that is used to secure wet stucco. Proper wall or plaster ceiling repair of severe cracks or chips, sagging, or discolored plaster requires patching and not filling.

Removing Old Plaster

If your home's plaster has suffered more than a simple hairline crack, you'll need to remove a section of stucco around the original plaster before you can apply your patch. Once plaster gets soft or brittle and then cracks, crumbles, or sags, it will weaken the adjoining stucco to which it's attached. In turn, this original plaster also needs to be removed with the damaged plaster before you perform any repair work.

Many homeowners, however, fail to remove enough old plaster to create a sufficient area for patching. To avoid this mistake, use a hammer and chisel and cut out at least an inch of plaster around the damaged area, in a straight square shape.

Cutting out plaster this way will give you plenty of room to add patching compound, ensuring that the space you create is broad enough to reach the home's framework or mesh used to secure the original plaster. This added room will also ensure your new patch stays securely in place.

Not Blending

Never assume you can add a plaster patch to a damaged wall or ceiling and then paint over the repaired area! New plaster can look a bit dented or splotchy when applied next to old plaster without proper blending techniques. To avoid unsightly and obvious areas of patching:

• Add drywall tape along the edges of a patch, which will then create an invisible seam between those two sections.
• After your drywall tape is applied, it's still essential to ensure that your plaster patch isn't undersized, sitting above the original plaster, or sagging below it. You may need to add more plaster layers or sand down your patch.

A plaster installer often takes hours and hours to apply various layers of plaster to ensure that all areas of a wall or ceiling are even, and you might need to do the same when you patch an area of damaged plaster in your home! Don't assume that adding a patched area of plaster is a quick and simple job, but be ready to spend lots of time adding needed layers of plaster or removing layers of a thick patch so that the repaired area blends seamlessly.

Ignoring Needed Structural Plaster Repair

Plaster is a very sturdy, durable compound that is difficult to crack or otherwise damage! While drywall might soften over the years and then warp, split, or break, plaster can remain intact for decades, if not even centuries, without showing signs of damage. The density and durability of plaster are why it's necessary to check for needed structural repairs before you fill or patch a damaged wall or ceiling.

• Sagging plaster often indicates a water leak behind a wall or above a ceiling; if this leak is left unrepaired, your home might suffer from structural damage and resultant mold growth.
• If plaster has cracked due to vibrations or because your house has settled and shifted, the home's joists or studs may be softened or bowed, and need replacement.

Don't make the mistake of merely covering over broken plaster, but check for the cause of that damage before performing any plaster repair work.

Not Checking the Lath or Wiring for Durability

As said, damage to interior plaster can indicate damage to a house's framework or structural materials. Water damage especially can spread to the lath or wiring behind the home's plaster, weakening this material so it won't be able to hold new patches or other repair compounds firmly.

• Before you add new sections of replacement plaster, be sure you check the lath or wiring for damage.
• If these foundation materials are soft, torn, misshapen, showing signs of corrosion, or otherwise unable to hold plaster patching, add a section of drywall to the home's ceiling joists or wall studs. New drywall will create a solid foundation for plaster patching so that your repair materials won't crack, sag, or even fall out of place.
• Be sure you attach the drywall with several screws across its front, rather than merely connecting a section of sheetrock at its corners. Added screws will keep the drywall secure over time, preventing it from sagging and then cracking.

Not Replicating Texture

If a plaster wall or ceiling has a flat design without any details, you might be able to repair a broken section of that plaster on your own. However, textured walls or ceilings, and especially intricate design work in plaster mouldings and medallions is often more difficult to repair and replicate than you might realize. Don't make the mistake of assuming you can use everyday household tools or even art supplies to recreate these details, as you might be very disappointed in your results!

• Swirl design on a wall or ceiling may be more planned and patterned than you realize. Swirls in the original plaster may be a particular size, and placed at a certain distance from each other; failing to mimic that pattern with new swirls you add after making your repairs can make for a very unattractive look!
• Duplicating intricate details in ceilings and crown molding may need quite a bit of artistic detailing. Many professional plaster repairpersons will take molds of unbroken areas of that design to recreate it in detail. Using a mold or cast allows you to create sections of plaster with that same design, as a patch for a damaged area.

Painting Before the Plaster Cures

Genuine plaster is not like joint compound, putty, or other such everyday filler materials. These materials are designed to dry quickly, so a homeowner can repair drywall or wood trim and then paint over that repair without delay. Real plaster, however, needs several days to cure and set thoroughly.

While plaster is drying, it's releasing moisture into the air. This moisture can bind to paint, causing it to bubble, flake, peel, and even bleed or fade. Don't make the mistake of thinking that an area of plaster wall repair only needs to be dry to the touch before it's ready for paint. Painting new plaster too soon can result in a blotchy paint job and color that is not true to the original, so that it stands out and is far too noticeable.

Failing to Use the Right Type of Plaster Repair

Plastering a home's walls and plaster ceiling repair are not as simple as applying layers of new material and then allowing it to dry. Various plaster mixtures are used to create walls and ceilings, and to create different finished looks and styles.

• Venetian plaster involves the application of several layers of plaster, all tinted different but similar colors. The last layer is buffed to create a shiny and luxurious appearance. A homeowner cannot merely add new gypsum over Venetian plaster and assume this patchwork will somehow blend with the original design.
• Large swirl designs are often created by twisting the edge of a trowel over wet plaster, while small hand tools are used for more intricate designs, for added precision.
• Textured walls and ceilings are often created by simply pulling a trowel straight back from wet plaster.

If you're not sure the right material or techniques to use for plaster repair in your home, it's best to leave this work to an expert.