Mold growth in a home can be a concerning and frustrating issue to deal with. Mold thrives in damp environments and can damage surfaces it grows on. When mold is discovered, a common question is whether you can paint over it or if more remediation is required first.
The short answer is that mold should not just be painted over without proper removal and preparation first. Mold can continue growing under paint and the paint will eventually bubble and peel. However, if mold is properly treated and the affected surface is prepared correctly, mold-resistant primers and paints can be effective at preventing future mold issues.
- Mold should never just be painted over without proper remediation first – it will continue growing under the paint and eventually ruin the surface.
- Affected areas must be prepped by killing, removing, and fully drying out mold before painting for best results.
- Using mold-killing primers and mold-resistant paints after prep can help prevent future mold growth.
- Extensive mold damage on porous materials may require replacement of the affected drywall, wood, etc.
- Identifying and fixing moisture problems is key to stop recurring mold issues long-term.
- Paint that was previously applied over mold will need to be safely removed first to deal with the underlying mold issue.
Why Mold Should Not Just Be Painted Over
Painting over mold may seem like a quick and easy solution, but it will not reliably kill the mold or stop it from growing again in the future. Here are some key reasons mold should not just be painted over:
Mold Will Continue Growing Under the Paint
Mold has root-like filaments that penetrate into porous surfaces like wood and drywall. Simply covering over mold with paint does not remove these filaments. The mold will continue spreading and growing under the paint.
Painted Over Mold Looks Better Temporarily But Peels Off
At first, painting over mold can make the affected surface look cleaner. However, this only masks the issue temporarily. As the mold continues growing under the surface, it will cause the paint to bubble, crack, and peel away.
Painting Over Mold Traps Moisture and Odors
Mold needs moisture to thrive. Painting over mold seals in moisture underneath, creating ideal conditions for continued mold growth. It also traps musty odors from the mold rather than removing them.
Hidden Mold Growth Can Lead to Bigger Problems Later
As mold spreads out of sight under paint, it can cause extensive damage to the surface it’s growing on. Drywall or wood colonized by mold can develop serious structural issues and require replacement. Catching and treating mold early is always preferable.
Painted Over Mold is an Ongoing Health Hazard
Mold releases allergenic spores and mycotoxins that can cause respiratory issues and other health problems in humans and pets. Painting over mold does not remove the health hazards of mold—it conceals them. Occupants may continue being exposed to mold toxins.
Clearly, just painting over mold is not an effective solution. Mold must first be killed, removed, and dried out completely before painting to achieve lasting results.
How to Properly Prepare a Surface After Mold Growth
To paint effectively over an area where mold growth has occurred, the surface must be prepared properly to kill and remove all mold. Here is the recommended process:
Step 1: Eliminate or Repair Any Moisture Sources
The first step is to address what allowed mold to start growing in the first place. Locate and fix any water leaks, humidity issues, condensation problems, or other moisture sources. Mold can recur quickly if the damp conditions that encouraged its growth remain.
Step 2: Kill and Remove Mold Growth
Next, the existing mold needs to be killed and cleaned away. This can be done by scrubbing the affected surface with detergent mixed with a mold-killing solution, such as bleach, borax, vinegar, hydrogen peroxide, or other dedicated mold removers. Be sure to protect eyes and skin.
Remove any porous materials like drywall or wood that are very colonized. A HEPA vacuum can help remove mold spores and residue after scrubbing. Mold killing foggers or ozone treatments may also be used.
Step 3: Dry Out the Area Thoroughly
All affected surfaces should be completely dry before painting or primer is applied. Use fans, heaters, or dehumidifiers to fully dry out the area after mold removal. Moisture meters can be used to check if surfaces are dry enough.
Wait at least 24 hours after drying before painting. Porous surfaces may need even longer to dry out fully. Rushing the drying risks trapping moisture under the paint.
Step 4: Apply a Mold-Killing Primer
Once the area is clean, dry, and free of any lingering mold, a coating of mold-killing primer should be applied before painting. Primers like KILZ or Zinsser Mold Killing Primer contain biocides that prevent future mold growth.
Be sure to wear protective equipment when applying mold-killing primers. Ventilate the area well. Allow the primer to fully dry as indicated before painting over it.
Using Mold-Resistant Paints and Primers
In addition to regular interior paint, specific mold-resistant paints and primers can provide added protection and prevention against mold. Here’s how they work:
Primers formulated to kill mold contain anti-microbial additives or biocides that inhibit mold growth. KILZ and Zinsser each make popular mold-killing primers. By coating surfaces with these products first, it prevents mold from taking hold again.
Paints labeled as “mold-resistant” or “mildew-resistant” have agents added to them to combat mold. This is usually zinc oxide, sodium borate, or other antifungal ingredients. Using mold-resistant paint adds an extra layer of protection against mold recurring.
How Effective Are They?
Both mold-killing primers and mold-resistant paints can be very effective when used properly as part of a mold remediation process. However, they cannot prevent mold on their own if excessive moisture is still present. They complement fixing moisture problems, not replace it.
Proper surface prep and application is also key. These products inhibit mold growth on the surface they are applied to. If there is hidden mold growth underneath the surface, they cannot reach and kill the roots of the mold.
When Drywall or Wood May Need Replacement
In severe mold cases, the affected drywall, wood, or other porous materials may be too colonized and require replacement. Here are signs it may be beyond cleaning and painting:
- Visible mold covering a large area, more than 10 square feet
- Signs of serious water damage from leaks or flooding
- Soft, warped, or crumbling drywall or wood from mold damage
- Musty odor remains strong even after cleaning efforts
- Mold keeps returning quickly after removing it
- Mold has grown into the paper backing of drywall
If the material is structurally damaged by mold, cleaning and painting over it will not resolve the underlying problem. Replacement of the affected drywall, wood, or other porous materials provides the only permanent solution.
Some signs of minor mold growth can often still be addressed just by cleaning, drying, priming, and painting the surface effectively. But recurring severe mold is a sign that replacement is needed.
Causes of Recurring Mold Issues
If mold continues to return after removing and painting over it, there is still a moisture issue that needs correction. Here are some common culprits of recurring mold:
Insufficient Drying Before Painting
Trapped moisture under surfaces is a recipe for recurring mold. Ensure all affected areas are completely dry before priming and painting. Wait at least 24 hours after cleaning up mold before painting.
Lingering Moisture Sources
Look for any water leaks, high humidity levels, condensation, flooding, or other moisture sources that have not been fully corrected and resolved yet. Mold can quickly return if the damp conditions that led to it remain.
Contaminated HVAC Systems
Mold spores in air ducts or on coils of heating/cooling systems can spread it throughout a building. Having HVAC systems professionally cleaned may be necessary.
Porous Materials Not Replaced
Moldy drywall, wood, carpet, or insulation that has not been removed provides food for mold to continue growing. Replacement of colonized porous materials may be needed.
When mold issues persist, there is always an underlying moisture problem that needs to be identified and corrected in order to prevent mold from taking hold again.
Safely Removing Paint Applied Over Mold
In some cases, previous homeowners or landlords may have hidden mold by painting over it. If you suspect this is the case, you’ll need to remove the paint safely to deal with the underlying mold properly.
Here are some methods to try removing paint applied over mold:
- Chemical paint strippers – Apply a liquid paint stripper to dissolve the paint so it can be more easily scraped off. Ensure good ventilation.
- Power washing – Outdoors, a pressure washer may be able to remove paint covering mold on siding or other solid surfaces.
- Sanding – Use a sander or sandpaper to strip paint down to the bare surface. Try wet-sanding to reduce dust.
- Scraping – For small areas, you may be able to carefully scrape away paint using a plastic putty knife, 5-in-1 tool, or other scraper.
- Heat gun – A heat gun can soften paint to make it easier to remove. Be very careful not to ignite paint fumes or damage the surface below.
Safety precautions are very important when dealing with paint that is covering up mold:
- Wear proper PPE – An N95 respirator mask, goggles, gloves, and protective clothing.
- Contain dust/debris – Use plastic sheeting and negative air machines with HEPA filtration.
- Minimize fumes – Use chemical strippers outdoors or in well-ventilated areas only.
- Check for asbestos – Have old paint tested for asbestos, which requires special removal.
- Dispose of properly – Seal paint chips and debris in plastic bags for proper hazardous waste disposal.
Thorough cleaning, drying, and mold removal will be much easier once any paint covering up mold growth is removed first. It also allows you to check the full extent of the mold issue.
Dealing with mold that was hidden under paint requires patience and safe removal methods. But eliminating the underlying mold issue is worth the effort to prevent future headaches.
While painting over mold may seem like a quick fix, it will only lead to larger problems down the road. But with proper remediation and preparation, surfaces can be painted effectively after mold issues occur. Following mold removal best practices, applying mold-inhibiting primers and paints, and addressing moisture problems provides the best defense against mold returning in the future. With the right process, you can feel confident that mold will not grow back under a fresh coat of paint.