What is the primary purpose of backer boards in tile installations for moisture-prone areas?

• A. Provide a stable, moisture-resistant substrate for tile installation
• B. Increase wall weight
• C. Improve color uniformity
• D. Replace waterproofing membranes

Answer: (A)

The main idea is to provide a solid, moisture-resistant base for tile work. In areas likely to see water or humidity, tiles need a substrate that stays stable and won’t deteriorate when damp. Backer boards—cementitious or fiber-cement boards—offer that dependable foundation, resisting moisture and keeping a flat, rigid surface for thin-set mortar to bond to. This prevents tiles from loosening, cracking, or delaminating that can happen when using standard drywall or plywood in wet areas. They don’t replace waterproofing membranes; those membranes still manage moisture on the surface, while the backer board gives a durable base behind the tiles. Increasing wall weight or affecting color uniformity aren’t the purposes of backer boards.