If drywall becomes damp, there are several repair options, including replastering, spot repairs, and moisture-proofing treatments.
Replastering
Damp-damaged drywall can deform and experience a decline in performance.
A simple method is to apply two coats of clear sealant oil to the surface to seal the damp plaster. However, this will reduce the board's strength and may cause it to warp after drying.
The most reliable method to ensure quality is to remove and replaster the affected section. In many cases, severely damp drywall cannot be effectively spot-repaired; complete removal and replastering is the only viable option.
Spot Repair
First, use a putty knife to scrape away any moldy areas on the drywall.
Once the surface is prepared, allow the drywall to dry completely. Then, apply a primer to the exposed areas, using a brush to spread it evenly over the entire work surface.
After the primer dries, apply a layer of mildewcide to prevent future mold growth. Next, apply a coat of whitewash. This step is crucial: ensure both sides of the board are coated, leaving no missed spots. After the first coat, inspect for any rust spots and wait for it to dry completely before applying a second coat.
Once the whitewash is applied, sanding is essential to prevent bubbling and bulging, which can severely affect the final appearance. Furthermore, the repaired area must be properly protected after application to prevent damage.
Moisture-Proofing Treatment
Lay a moisture-proof barrier, such as plastic sheeting or a damp-proof membrane, beneath the drywall. This effectively isolates ground moisture and prevents it from penetrating the board.
During installation, pay special attention to the joints between boards. Use a specialized sealant or waterproof adhesive to fill and seal these joints, effectively preventing moisture ingress.
Maintaining good ventilation and dryness in the room is also an effective moisture-proofing measure. Ensure good air circulation by installing ventilation systems or opening windows regularly. During everyday use, clean and dry the surface promptly and avoid placing damp items directly on the drywall.