Building Materials Exam 2 Practice

Moisture resistance in a substrate is crucial for wet areas because the material must not absorb water, swell, or promote mold and deterioration when exposed to humidity or direct splashes. Cement board fits this need best among common options because it is a cementitious, dense substrate that resists water infiltration and provides a stable base for tile and thinset. It doesn’t swell or warp like some wood products and doesn’t crumble like gypsum-based boards when exposed to moisture, making it ideal for showers, tub surrounds, and other damp environments. Plywood can handle some moisture better than gypsum products, but it can still rot, delaminate, or warp with prolonged water exposure if not properly sealed and maintained, so it’s not the standard choice for wet zones. Gypsum wallboard and regular drywall have gypsum cores that readily absorb moisture, leading to swelling, mold growth, and deterioration in wet conditions, which makes them unsuitable for wet areas.