Do Laundries Need to Be Waterproofed? Laundry Waterproofing Requirements

Laundry rooms may not receive the same attention as bathrooms, but they are exposed to frequent moisture, plumbing connections, and appliance movement that can introduce water into the structure of a home. Washing machines, utility sinks, hoses, and drainage systems all increase the risk of leaks, splashes, and condensation.

So, do laundries need to be waterproofed? While not always explicitly required by code, yes, waterproofing a laundry is widely recognized as a best-practice safeguard—particularly in tiled areas, upstairs laundries, and locations with sinks or floor drains.

At ProLux Materials, we supply PROVA waterproofing systems designed to provide durable, integrated protection in laundry environments, helping builders and homeowners reduce long-term moisture risks while meeting modern installation standards.

Why Laundry Rooms Require Waterproofing

Laundries combine plumbing fixtures, floor penetrations, and repeated exposure to moisture within a compact space. Even small leaks from hoses or valves can allow water to migrate beneath floor finishes or behind cabinetry, where damage often goes unnoticed.

Common substrates such as plywood, concrete, and gypsum-based boards can absorb moisture over time. This can lead to swelling, mold development, odor issues, and deterioration of adhesives and finishes.

A properly installed waterproofing system creates a continuous barrier beneath visible surfaces. This barrier helps prevent water from reaching the structure below, even during appliance failures or accidental overflows. The objective is not only to protect surface finishes, but to preserve the integrity of the building envelope. PROVA Board Plus+ is particularly well suited for laundry walls, where it replaces moisture-sensitive drywall behind sinks, washer valves, and cabinetry.

Building Code Expectations and Industry Practice

While North American building codes do not formally classify laundries as wet areas, industry best practice often treats specific laundry zones—such as floors with drains and walls behind sinks—as intermittently wet environments.

When waterproofing is specified in laundry environments, membranes tested to ANSI A118.10 provide a recognized benchmark in North America for water resistance when installed beneath tile.

While local requirements vary, the underlying intent is consistent: limit moisture intrusion and protect adjacent rooms and structural components. In multi-story homes or apartments, waterproofing laundries above occupied spaces is especially important to help prevent ceiling and framing damage below.

Common Areas That Should Be Waterproofed in a Laundry

In practice, waterproofing in laundries typically focuses on the following zones:

Even where codes allow discretion, waterproofing remains a practical safeguard that helps stabilize substrates and support the long-term performance of tile, vinyl, or other hard floor finishes.

Materials Commonly Used for Laundry Waterproofing

Several waterproofing approaches are suitable for laundry installations, depending on the substrate and layout:

• Sheet Membranes: Bonded sheet membranes create a continuous waterproof layer beneath floor finishes. Systems such as PROVA Mat Waterproofing Membrane are well suited for laundries due to their durability and controlled installation process.
• Liquid-Applied Membranes: These membranes are applied in multiple coats to form a seamless layer once cured. They can be effective when installed to the manufacturer’s specified thickness.
• Foam-Core Waterproof Boards: PROVA Board Plus+ Waterproof Tile Backer Board is waterproof by design, using an XPS core with a reinforced surface. It functions as both a substrate and moisture barrier for walls behind sinks and appliances.

Using compatible components from a single system helps ensure proper detailing at joints, corners, and penetrations, reducing installation variability.

Best-Practice Approach to Laundry Waterproofing

Effective waterproofing relies on correct preparation and detailing:

Surface Preparation

Substrates should be clean, stable, and free of contaminants. Any cracks or voids should be addressed before waterproofing begins.

Membrane Installation

Bonded membranes are installed using compatible mortars or adhesives to achieve full contact with the substrate. Careful embedding helps avoid voids or trapped air.

Detailing and Drain Integration

Corners, seams, and penetrations require additional reinforcement using system-compatible bands and seals. Floor wastes must be properly integrated to maintain continuity.

Finish Installation

Once the waterproofing system is complete, finishes such as tile can be installed using approved setting materials.

Common Waterproofing Mistakes to Avoid

• Overlooking areas behind appliances where leaks are most likely to occur
• Inadequate seam or corner detailing
• Combining incompatible products from different systems
• Damaging the membrane during later installation stages

PROVA Waterproofing Systems for Laundry Environments

PROVA waterproofing systems supplied by ProLux Materials are designed as complete assemblies rather than isolated products. Bonded sheet membranes protect floors, while PROVA Board Plus+ panels provide waterproof, stable substrates for wall areas.

System-compatible accessories simplify detailing and help ensure consistency across installations. Components are tested to recognized standards, including ANSI A118.10 where applicable, supporting reliable performance in wet-area applications.

Long-Term Performance and Maintenance

Once installed, a properly waterproofed laundry requires minimal maintenance. Periodic inspection of sealant joints and penetrations helps ensure continued protection, especially if appliances are moved or replaced.

Because PROVA membranes are installed beneath finished surfaces, they remain protected from wear while continuing to act as the primary moisture barrier for the life of the installation.

Do Laundries Really Need to Be Waterproofed?

Yes. Water exposure in laundries is unavoidable, and the consequences of unprotected substrates can be extensive. Waterproofing helps limit damage, supports hygiene, and contributes to long-term building durability.

Using an integrated PROVA waterproofing system from ProLux Materials provides a reliable approach to managing moisture risks in modern laundry spaces.

Frequently Asked Questions

Is waterproofing mandatory for laundry rooms?

In most U.S. residential settings, waterproofing is not explicitly required by national building codes. However, waterproofing is commonly specified in multifamily buildings, commercial laundries, upstairs laundry rooms, and tiled areas with sinks or floor drains to reduce the risk of water damage to adjacent spaces.

Which waterproofing system is suitable for laundries?

Bonded sheet membrane systems combined with waterproof backer boards offer reliable protection when installed as a complete system.

Can waterproofing be installed over existing tiles?

No. Existing finishes must be removed so the waterproofing system can be correctly bonded to the substrate.

Do walls behind laundry sinks need waterproofing?

Yes. Wall areas exposed to splashes or condensation should be protected to prevent moisture damage behind cabinetry.

Why source waterproofing materials from ProLux Materials?

ProLux Materials supplies genuine PROVA waterproofing systems along with technical guidance, helping ensure correct system selection and installation.