Bathroom waterproofing is not optional, and most bathroom renovation failures trace back to inadequate or skipped waterproofing.
Why Bathrooms Fail
Tile and grout look solid. They're not waterproof. Grout is porous. Standard cement-board backer is porous. Water vapor from shower steam and direct water contact migrate through tile and grout and contact whatever is behind them. If the substrate isn't waterproofed, that moisture accumulates in the wall assembly, causes mold, and rots framing. In 3 to 7 years, the homeowner notices soft spots in tile, crumbling grout at the base, or a musty smell that doesn't go away.
The Proper Waterproofing Systems
Topical membrane (RedGard, HydroGard): Liquid-applied, rolled or painted onto cement board before tile is set. When cured, creates a continuous waterproof layer. Effective when applied correctly with two coats and attention to corners and penetrations.
Sheet membrane (Schluter Kerdi, WEDI): Fabric-reinforced sheets set in unmodified thinset over backer board. More labor-intensive than topical membrane, but creates a robust, tested system. Industry standard for custom shower builds.
What Contractors Skip and Why
A topical membrane adds approximately $200 to $400 in materials and one additional day of labor. Some contractors skip it to stay competitive on price. Some skip it because the client won't know the difference until the shower fails years later.
Vandenberg Construction uses membrane waterproofing on every wet application. It is a non-negotiable standard on every bathroom project.
What to Ask Before Hiring
Before hiring any contractor for bathroom tile work, ask specifically: what waterproofing system do you use in the shower? If the answer is "cement board is fine," find a different contractor.
Call (208) 582-8733 to discuss your bathroom renovation.