The short answer
Why Lath and Plaster Is Different
Lath and plaster walls are more porous than drywall. The plaster soaks up moisture, and the wood lath behind it can stay damp for a long time. That means mold can grow deep inside the wall, not just on the surface.
Cleaning the visible mold might make the wall look better, but it can leave mold spores and roots behind. If the moisture problem is not fixed, the mold will come back. You need to consider both the surface and the structure behind it.
When Surface Cleaning Can Work
For a small patch of mold on a sound plaster surface, you can try cleaning it yourself. Use a mild detergent and water, or a solution of vinegar and water. Wear gloves, goggles, and a respirator mask to avoid breathing in spores.
Scrub gently with a soft brush or sponge. Avoid saturating the plaster, as too much water can damage it. After cleaning, dry the area thoroughly with fans and keep the room ventilated. This works well when the mold is only on the surface and the plaster is not crumbling.
- Test a small area first to see how the plaster reacts
- Use a dry cloth to blot up excess moisture
- Keep the room dry for several days after cleaning
- If you see stains returning, the mold is deeper
- If the plaster is soft or crumbling, stop and call for help
When to Call the Pros
If the mold covers a large area, or if you notice a musty smell, the mold is likely inside the wall. Cleaning the surface will not solve that. The pros have equipment to find moisture and assess how deep the mold goes.
They can also handle the removal safely, especially if the plaster is damaged or the lath is rotted. In some cases, the affected section may need to be cut out and replaced. That is a job for professionals who know how to contain spores and dispose of materials properly.
Moisture Is the Root Problem
Mold needs moisture to grow. If you clean the mold but do not fix the leak or humidity issue, it will return. Look for the source of water: a roof leak, a plumbing leak, or condensation from high indoor humidity.
In a humid climate like Rockwall, keeping indoor humidity below 50 percent helps prevent mold. Use exhaust fans in bathrooms and kitchens, and fix any leaks quickly. If you are not sure where the moisture is coming from, a water damage inspection can help find it.
- Check for visible leaks around windows and pipes
- Use a dehumidifier in damp rooms
- Ventilate after showers and cooking
- Fix roof and plumbing leaks as soon as you notice them
- Monitor humidity with a simple hygrometer
Health and Safety First
Mold can cause respiratory problems, allergies, and other health issues. If you feel unwell, see a doctor. If you have asthma or a weakened immune system, avoid cleaning mold yourself and ask someone else to do it.
When you clean mold, always wear protective gear. Keep the area ventilated and seal off other rooms if possible. If the mold covers more than a small patch, or if you are unsure about your safety, contact local water damage pros for an assessment.
Need help right now?
Phones are answered 24/7 for Rockwall and nearby communities.
Call Now (469) 698-4610Frequently asked questions
Can I just paint over mold on lath and plaster?
Painting over mold does not kill it and the mold can bleed through the paint. It also does not address the moisture problem. You need to clean the mold properly first, and fix the moisture source, or the mold will return.
How do I know if mold is inside the wall?
A musty smell that persists, or mold that reappears after cleaning, are signs the mold is deeper. You may also see stains or bubbling on the plaster surface. In that case, professional assessment is wise.
What should I do if the plaster is crumbling?
If the plaster is soft or crumbling, do not try to clean it yourself. It may contain mold and debris that can become airborne. Contact the pros to evaluate the wall and plan for safe removal and repair.