What is moisture resistant drywall?

Moisture resistant drywall is specially treated gypsum board designed to withstand humid conditions better than standard drywall, making it ideal for bathrooms, basements, and other moisture-prone areas in Ottawa homes.

This specialized drywall features a treated gypsum core and moisture-resistant facing that helps prevent the board from breaking down when exposed to humidity. The paper facing is typically treated with wax or other moisture-repelling compounds, and some versions use fiberglass mesh instead of paper entirely. You'll often see it labeled as "MR board," "green board" (due to its traditional green color), or "blue board."

Key applications in Ottawa homes include bathroom walls behind tile, basement finishing projects, laundry rooms, and mudrooms. It's particularly valuable in Ottawa's climate where freeze-thaw cycles can create condensation issues, and where basement moisture is common in older homes throughout areas like the Glebe, Centretown, and post-war neighborhoods in Alta Vista and Elmvale.

Important limitations to understand: moisture resistant drywall is NOT waterproof and shouldn't be used in direct shower areas or as a tile backer in wet zones. For those applications, you need cement board, Hardiebacker, or other tile backer systems. The Ontario Building Code requires proper vapor barriers and ventilation regardless of drywall type, especially in bathrooms and basements.

Installation considerations are similar to standard drywall, but proper sealing of joints and edges is even more critical. In Ottawa's humid summers and dry winters, expansion and contraction can create gaps if not properly finished. The cost premium is typically 20-30% over standard drywall - expect to pay around $15-25 per sheet versus $12-18 for regular drywall.

Professional guidance: While homeowners can install moisture resistant drywall themselves, basement applications often require permits through the City of Ottawa, especially if you're creating finished living space. Electrical work for outlets and lighting requires ESA permits and should be completed before drywall installation.

Next steps: Assess your specific moisture conditions, ensure proper ventilation is planned, and consider whether you need moisture resistant drywall or a more robust solution like cement board for high-moisture areas.