Mold is a common problem in many homes. It thrives in damp, humid environments and can grow on a variety of surfaces, including walls. Mold is not just an aesthetic issue, but a health concern as well. Some types of mold release spores and mycotoxins that can cause allergic reactions and respiratory problems in people. That’s why it’s important to address any mold issues quickly and properly.
A common question homeowners have is whether painting over moldy walls will remove the mold. The short answer is no. Painting over mold is not an effective solution and will not remove the mold growth. Here’s a more in-depth look at why painting walls does not remove mold.
Painting Does Not Kill Mold or Remove Mold Spores
Paint is purely cosmetic – it may cover up the appearance of mold, but it does not fix the root cause of the mold growth. Mold needs moisture to thrive. It grows into walls, drywall, wood and other materials when excess moisture is present. Painting does nothing to address this moisture source. The mold will continue to grow and spread underneath the paint.
In addition, mold releases microscopic spores that easily become airborne. These spores will still be present even after painting over mold. Painting simply traps the mold behind the paint, along with the moisture that is feeding it. The mold will eventually break through the paint as it continues growing. Any disturbance of the painted mold, such as sanding or scraping, will release spores into the air.
Paint May Encourage Mold Growth
In some cases, painting over mold can actually make the problem worse. Paint essentially seals the mold underneath it, preventing proper drying and creating a humid environment. This trapped moisture provides ideal conditions for continued mold growth under the paint.
Using oil-based paints in particular should be avoided, as oil paints do not allow moisture to pass through. The moisture becomes trapped between the oil paint and the wall surface. Mold will take advantage of this moisture barrier and spread under the paint.
Properly Removing Mold Requires Killing the Roots
To truly address a mold issue, you need to kill the roots and remove the colony. Surface mold is just a small part of the mold growth – most mold growth happens in the subsurface material it is growing on. Simply scraping off surface mold or applying paint does not remove all the mold roots.
Mold roots can penetrate deep into porous materials like drywall, wood studs and ceiling tiles. To fully remove mold, you need to use products that can kill and remove this subsurface growth. Bleach solutions, antimicrobial chemicals and detergents that remove mold at the root level are necessary.
Professional Mold Remediation May Be Needed
For severe mold infestations, professional mold remediation is often required. Mold remediation contractors use powerful HEPA vacuums, antimicrobial agents, negative air pressure containment and other professional techniques to thoroughly remove mold. They can also find and fix the moisture issues triggering the mold growth.
Professional remediation has the advantage of completely removing mold at the roots and ensuring spores are not spread throughout the home during the process. It also reduces health risks to residents. However, professional remediation can be expensive.
Steps for Safely Removing Mold from Walls
For smaller areas of mold growth, homeowners may choose to tackle the issue themselves. Here are the basic steps for properly removing mold from walls:
1. Protect yourself
Wear protective gear when working with mold. An N95 respirator mask, goggles, gloves and coveralls help minimize exposure to mold spores and mycotoxins. Make sure to isolate the affected area from the rest of the home as much as possible.
2. Identify and fix the moisture source
Determine what is causing excess moisture leading to the mold growth. Common culprits include roof leaks, plumbing leaks, condensation, flooding and humidifiers. Fix any leaks or moisture issues before removing the mold, or it will simply grow back again.
3. Scrub surfaces with detergent
Use a non-ammonia detergent or commercial mold cleaner to scrub visible mold off surfaces. This helps remove surface mold. Make sure to protect skin and eyes from cleaners.
4. Apply antimicrobial chemical treatment
Use a commercial antimicrobial solution designed specifically to kill mold and mold roots. Let it soak into the affected areas according to product instructions. Bleach can also be used in a diluted solution.
5. Lightly sand affected drywall
Use a pole sander with 80-120 grit sandpaper to lightly sand moldy drywall and surrounding areas. This helps remove subsurface mold roots. Vacuum sanded areas immediately using a HEPA vacuum to contain spores.
6. Dry out the area rapidly
Use fans, dehumidifiers and open windows to fully dry out the affected area and surrounding materials as much as possible. Mold requires moisture to survive, so a thoroughly dried area helps prevent recurrence.
7. Carefully discard damaged materials
Bag up any mold-damaged surface materials like drywall, insulation and ceiling tiles for disposal. Make sure to contain dust and debris during removal to prevent spreading spores. Wear protective gear while handling moldy materials.
8. Clean and sanitize surrounding areas
HEPA vacuum surrounding areas like stud bays, subfloors and joist cavities to remove any remaining mold residue and spores. Use antimicrobial spray to sanitize the area.
9. Allow surfaces to completely dry
Allow all affected surfaces to thoroughly dry before rebuilding. Use dehumidifiers and fans to facilitate drying. Surfaces should remain mold-free, provided excess moisture issues have been corrected.
10. Replace removed materials and rebuild
Once the underlying surfaces are clean, dry and mold-free, the area can be rebuilt. Replace any structural materials that were removed. Prime surfaces before painting or rehanging drywall.
Protective Paint Additives May Help
While paint does not kill or remove mold, certain mold-resistant paint additives may offer some protective value against mold recurring. Look for paints containing mildewcide additives or EPA-registered antimicrobial ingredients. Be sure the affected area is completely dry before application.
It’s important to note that antimicrobial paint alone will not remove established mold growth. It must be used in tandem with full mold removal steps. However, antimicrobial paints may help protect dry surfaces against future mold growth.
When Painting Over Mold is Acceptable
Painting over mold is generally not recommended. However, in cases where the mold growth is very minor and limited to a small surface area, painting may be acceptable after proper mold removal steps. Here are some instances where painting over treated mold may be appropriate:
- The affected surface area is less than 10 square feet
- The mold growth is completely surface level and very thin
- The moisture source has been fully eliminated
- Mold on framing or studs has been sandwiched between two moisture barriers
- Antimicrobial primer is used before repainting
Again, painting should only be done after full mold removal treatment using detergents, antimicrobials, drying and HEPA vacuuming. The area must be completely dry before repainting.
Signs Mold Remains Under Paint
Here are some warning signs that mold persists underneath new paint application:
- Painted area starts bubbling or peeling
- Flaky surface develops under paint
- Dark spots appear as mold bleeds through paint
- Paint develops a blackened, sooty appearance
- Musty odors come from behind painted area
- Continued moisture or humidity issues in the area
If you see these issues, it means the mold was not properly remediated before painting. The paint is merely covering up an ongoing mold issue. It’s important to halt the mold growth by readdressing the affected area.
Alternative Options for Covering Mold on Walls
Since painting does not truly address mold growth, here are some other options for covering walls after mold problems:
Wallpaper
Like paint, wallpaper only conceals mold rather than removing it. However, certain antimicrobial, mold-resistant wallpapers using vinyl or other impermeable materials may help prevent recurrence. Make sure the wall surface is thoroughly cleaned and dried before application.
New Drywall
For extensive mold damage, replacing affected drywall completely may be needed. Professional mold remediators can remove contaminated drywall, clean and treat underlying areas, then install fresh new drywall. All mold roots will be eliminated.
Wood Paneling/Wainscoting
Wood paneling or wainscoting can create an attractive cover over mold damaged walls, especially in basements. Use mold resistant materials and make sure the wall is structurally sound, properly dried and treated for mold before application.
Plastic Wall Panels
Plastic wall panel systems like PVC can effectively seal off moldy walls after remediation. Plastic is mold resistant and prevents moisture from reaching the contaminated surface. Panels are also easy to clean and disinfect.
Preventing Mold from Recurring
To keep mold from repeatedly growing back after remediation, here are some tips:
- Maintain low indoor humidity – keep below 50% RH
- Promptly fix any water leaks or moisture sources
- Ensure proper ventilation in bathrooms, basements and attics
- Clean bathroom and kitchen surfaces regularly to remove mold food sources
- Have HVAC systems professionally cleaned and disinfected
- Avoid carpeting in moisture-prone areas
- Dehumidify basements and crawl spaces
- Use exhaust fans when cooking and showering
Professional Mold Testing and Remediation
For homeowners dealing with persistent or severe mold issues, professional mold testing and remediation services may be advised. Certified industrial hygienists can test to identify hazardous mold levels and species. Professional mold contractors have the tools, training and protective equipment to fully eliminate mold and prevent spore exposure.
Professional mold remediation involves:
- Detailed inspection to find all mold
- Mold testing and analysis
- Addressing moisture sources
- Local containment systems
- Powerful HEPA vacuuming
- Antimicrobial and biocide treatment
- Dehumidification systems
- Complete mold removal and elimination
- Detailed drying of affected materials
- Reconstruction and rebuilding services
- Post-remediation mold testing
Though professional services have a greater upfront cost, they can prevent pricier reconstruction work later on if mold reoccurs. Remediation pros can also provide guidance on preventing further mold outbreaks.
In Conclusion:
- Painting over mold is not an effective solution, as paint does not kill mold or remove spores
- Paint can actually create a moisture barrier that encourages more mold growth
- To fully remove mold, the roots must be killed and affected materials properly cleaned and dried
- For severe cases, professional mold remediation is recommended
- Preventing moisture buildup is key to stopping mold at the source
- With proper remediation, moldy walls can be repaired and free of recurring mold
While painting over mold may seem like a convenient short-term fix, it will allow mold to continue spreading unchecked. Stopping mold growth requires getting to the roots of the problem through professional or thorough DIY mold removal techniques. Along with fixing moisture issues, this provides the best protection against persistent mold problems.
