How do you deal with moisture and mold issues in plaster and joint compound walls?

1 Plaster vs joint compound

Plaster is a mixture of lime, sand, and water that hardens into a durable and smooth surface. Joint compound, also known as drywall mud, is a paste of gypsum, water, and additives that is used to fill gaps and seams between drywall panels. Plaster is more expensive and labor-intensive than joint compound, but it also offers better sound insulation, fire resistance, and aesthetic appeal.

2 Moisture and mold problems

Both plaster and joint compound can be affected by moisture and mold if they are exposed to water leaks, high humidity, or poor ventilation. Moisture can cause plaster to crack, crumble, or detach from the lath (the wooden strips that support it). Joint compound can swell, soften, or peel off the drywall. Mold can grow on both materials and cause health problems, such as allergies, asthma, and infections.

3 How to prevent moisture and mold

To prevent moisture and mold problems, it is important to avoid water intrusion and maintain good air circulation in your home. This can be done by fixing any plumbing leaks, roof leaks, or foundation cracks that can cause water to seep into your walls or ceilings. Additionally, you should install a vapor barrier, such as plastic sheeting, behind your plaster or drywall to prevent moisture from condensing on the surface. To reduce the humidity level in your bathroom, kitchen, or basement, you can use a dehumidifier, an exhaust fan, or a window. Finally, painting your plaster or joint compound with a mold-resistant primer and paint can create a protective layer.

4 How to treat moisture and mold

If you notice any signs of moisture or mold damage on your plaster or joint compound, it is important to act quickly. Start by cutting off the water supply and repairing the leak that caused the damage. Then, use a utility knife, hammer, or chisel to remove any wet or moldy plaster or joint compound. Be careful not to damage the underlying structure or wiring. Clean the exposed area with a solution of bleach and water or a commercial mold remover, wearing gloves, goggles, and a mask to protect yourself from mold spores and chemicals. Finally, replace the damaged plaster or joint compound with new material, following the manufacturer's instructions and using the appropriate tools and techniques for your project.

5 How to choose the right material

When deciding between plaster and joint compound, you should consider your budget, skill level, and design preferences. Plaster is more suitable for older homes, historic buildings, or custom projects that require a high-quality and elegant finish. It can also handle minor movements and vibrations better than joint compound, but is more difficult and costly to install, repair, or modify. Joint compound is more suitable for newer homes, standard buildings, or DIY projects that require a fast and easy finish. It can also accommodate electrical outlets, switches, and fixtures more easily than plaster, but is more prone to cracking, sagging, or shrinking. Additionally, joint compound offers less sound insulation, fire resistance, and aesthetic appeal.