In almost all cases, it's important to repair damaged plaster before you try to paint the surface
Imagine you’re ready to paint a room in your home. You’ve spent weeks picking the precise shade you want. You’ve gathered, purchased, or borrowed all the tools and equipment you need. You’ve cleared the weekend’s schedule. You’re ready to go! But when you move the furniture away from the walls, you’re surprised to find a damaged spot of plaster.
Can you just paint over it and hide the spot with furniture again? The short answer is almost always “no.” Instead, repair the plaster first, then paint. Here’s why.
Can You Paint Over Damaged Plaster?
The primary reason for the “repair first” rule is pretty simple: Painting over damaged plaster only covers up the problem without doing anything to address it. It might look good for a short while, but you’re probably missing something that can be fixed with a bit of effort.
Over time, a painted-over bit of damaged plaster can even affect the integrity of the plaster itself. If the underlying damage isn’t repaired properly, it may expand and spread.
In some cases, that expanding damage might ultimately cause large chunks of plaster to fall. And because plaster can be heavy, falling chunks of plaster could potentially hurt someone.
Do You Need to Prepare the Surface Before Painting Over Plaster?
Another reason you should repair damaged plaster before you paint over that damaged spot has to do with the paint itself. You need to properly prepare the surface if you want the paint to adhere properly. That’s the best way to keep the painted surface looking good for years to come. A great, long-lasting paint job requires a properly primed and smoothed surface.
Often, painted-over damaged plaster results in paint failures, such as chips, cracks, or bubbles. That paint failure could extend beyond the border of the damaged spot. Over time, the paint could necessitate an even bigger repair job. You might also have a hard time matching the paint color weeks or months later.
Prime and Paint the Repaired Plaster
It’s important to properly prepare any surface in your home before you paint. In addition to repairing the damaged plaster, that usually means applying a coat or two of the appropriate primer. If the damaged bit of plaster is only a water stain and there’s no underlying leak that will recur, use a stain-blocking primer such as a Kilz sealant. Once that’s dried, you can proceed to paint the area.
You also need to choose the right kind of paint for the project. In most cases, the best paint for plaster walls is a high-quality latex formula. If the room you’re painting is near a bathroom, laundry room, or other damp area of the home, select a paint with a satin finish.
Identify the Cause of Plaster Damage Before You Repair It
Before you decide to merely patch over a small bit of damaged or cracked plaster, take the time to investigate the cause thoroughly. Patching over damaged plaster might seem perfectly adequate at first. Small spots in particular may seem inconsequential, and if you’re going to patch it up before you paint over it, why worry?
However, repairs won’t solve the problem if the underlying cause can recur. For example, if the cause of the damage is a slow leak or broken pipe behind the plaster wall, you’ll likely have continual damage until you repair the cause of the leak.
Cost to DIY Plaster Repair vs. Hire a Pro
Painting a room is usually a great DIY project for homeowners to tackle themselves. However, that doesn’t necessarily mean you should also repair damaged plaster that’s preventing you from getting started on that paint project.
Damage to plaster isn’t as easy to repair as damage to drywall or sheetrock, which comes in solid sheets that you can simply cut and patch into the wall or ceiling. Instead, it must be applied carefully, layer by layer. It dries quickly to a consistency that isn’t terribly forgiving to beginner mistakes.
Moreover, many plaster walls were constructed prior to the 1978 ban of lead paint, which can present serious health hazards if you’re not properly equipped, trained, and prepared. Dealing with lead paint safely requires an EPA-certified professional.
For these reasons, it’s better to hire a professional plasterer near you. Since the average cost to plaster a 100-square-foot wall is typically around $510, you can expect to pay an average of anywhere between $30 and $80 per hour to repair a plaster wall. Ask the professional to identify the cause of the damage so you can get the underlying problem resolved before the contractor finishes the repair.