Proper waterproofing is critical for the longevity and integrity of a residential shower. The process begins with preparing the substrate: ensure it is clean, dry, structurally sound, and free of any contaminants. For cement board or drywall, a liquid-applied or sheet membrane waterproofing system must be installed. The waterproofing membrane should be applied meticulously to all surfaces that will be in contact with water: the floor, the lower portion of the walls (typically at least 6 inches up, but often the entire wall), the shower curb, and any built-in niches or seats. For liquid membranes, typically two coats are applied, ensuring complete coverage and allowing adequate drying time between coats as per the manufacturer's instructions. For sheet membranes, ensure proper overlap (usually several inches) at all seams and carefully seal around all penetrations like shower arms and drains. The membrane should extend onto the subfloor and integrate with the shower pan liner if one is used. A continuous, monolithic barrier is the goal, with no gaps or vulnerabilities where water can penetrate to the underlying structure.

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