If drywall has been exposed to rain, it may be compromised and should not be used. Water can damage drywall by causing it to swell, warp, or develop mold and mildew, which can affect its structural integrity and make it unsuitable for use.
Here are some considerations regarding rain-damaged drywall:
Assess the extent of the damage: Inspect the drywall for visible signs of water damage, such as discoloration, warping, or soft spots. If the damage is limited to the outer edges and does not affect the core of the drywall, you may be able to salvage those parts by cutting away the damaged sections. However, if the damage is widespread or affects the core, it's best to err on the side of caution and not use the wet drywall.
Mold and mildew risk: Even if the drywall appears undamaged, it can still harbor moisture, which creates an environment conducive to mold and mildew growth. Mold can pose health risks and compromise indoor air quality, so it's crucial to prioritize safety and not use wet or potentially mold-contaminated drywall.
Drying time: If the drywall got wet but does not show signs of damage, you may consider drying it thoroughly. However, this process can be time-consuming, and it's difficult to ensure complete dryness, especially within the core of the drywall. Damp or partially wet drywall can lead to hidden issues and is not recommended for use.
Ultimately, it is generally best to avoid using drywall that has been rained on. Speak with your contractor about the situation and consider obtaining replacement drywall to ensure the integrity and quality of your project.