Tile Underlayments That Comply with ANSI A118.10

Built for Wet Zones: Tile Underlayments That Comply with ANSI A118.10

Waterproofing isn’t optional in wet areas—it’s code. Whether it’s a hotel shower stall, a commercial kitchen floor, or a multi-unit bath renovation, tile underlayments must do more than hold up tile—they must stop moisture dead in its tracks. For distributors serving commercial contractors, knowing which underlayments comply with ANSI A118.10 isn’t just helpful—it’s essential.

The ANSI A118.10 standard defines performance requirements for load-bearing, bonded, waterproof membranes used beneath thin-set ceramic tile and stone. Simply put: if the job involves water exposure and tile, you need a membrane that meets this spec.

What ANSI A118.10 Actually Covers

Developed by the Tile Council of North America (TCNA), ANSI A118.10 specifies the minimum performance criteria for sheet-applied and liquid-applied membranes. This includes standards for:

Waterproofness

Seam strength

Dimensional stability

Crack isolation

Mold resistance

Short-tail keywords: ANSI A118.10 membrane, waterproof tile underlayment, thin-set waterproofing membrane

Compliant products are tested to withstand water penetration, expansion, and contraction stresses—critical in areas where moisture can lead to mold, efflorescence, or substrate failure.

Where ANSI A118.10 Membranes Are Required

You’ll find A118.10-specified membranes in:

Shower pans and curbless bathrooms

Commercial kitchens and dish rooms

Locker rooms, saunas, and spas

Laundry areas and mechanical rooms

Exterior balconies with tile finishes

In many jurisdictions, code inspectors won’t sign off on wet-area installs without documentation that the underlayment complies with ANSI A118.10.

Types of Membranes That Meet the Standard

1. Sheet-Applied Membranes

These are factory-manufactured sheets made from polyethylene, polypropylene, or similar materials. They’re applied over substrates with thin-set mortar and offer excellent uniformity and coverage.

Pros:

Fast installation

Consistent thickness

High tear resistance

Popular in: hospitality, multifamily units, and modular builds where speed matters.

SEO phrase: sheet waterproofing membrane for showers

2. Liquid-Applied Membranes

These are roll-on or trowel-applied coatings that cure to form a flexible, waterproof film. They’re ideal for complex shapes or hard-to-reach areas.

Pros:

Great for irregular surfaces

No seams or overlaps

Some offer crack-bridging performance

Long-tail keyword: liquid waterproof tile underlayment for wet areas

3. Fabric-Reinforced Hybrids

Some liquid membranes are paired with reinforcing fabric for added strength and seam control. These hybrid systems balance flexibility with durability and are often used in institutional and hospital settings.

Performance Features to Look For

Whether stocking for a multifamily renovation or a commercial build, ensure the tile underlayment offers:

ANSI A118.10 compliance (clearly marked on product literature)

Compatibility with latex-modified thin-set mortars (A118.4 or A118.11)

Mold and mildew resistance for long-term hygiene

Crack isolation properties (many membranes also meet ANSI A118.12)

Seam and transition accessories for drains, corners, and edges

Keyword: thin-set waterproofing membrane with crack isolation

Installation Advantages That Matter to Contractors

Contractors want underlayments that install cleanly, pass inspection, and reduce rework. Top concerns include:

Cure time: fast-drying liquid membranes help keep schedules on track

Compatibility: some membranes require specific primers or thin-sets

Ease of cutting: sheet membranes should cut cleanly and lay flat without curling

Manufacturer support: product data, installation guides, and warranty coverage influence buying decisions

Distribution Strategy for Buldix Partners

Stocking ANSI A118.10-compliant membranes positions you as a go-to supplier for tile contractors working in wet zones. Consider these SKUs:

3′ and 6′ rolls of sheet membranes with prefabricated inside/outside corners

1-gallon and 5-gallon pails of liquid-applied waterproofing

Reinforcement fabric and detail strips

ANSI-compatible drain flashing kits and tile edge accessories

Pro tip: bundle waterproofing membranes with compatible mortars and backer boards to create ready-to-install kits.

Educating the End Buyer

Even experienced tile installers may not always understand the spec. Questions your team should be ready to answer:

“Does this product meet ANSI A118.10 for waterproof showers?”

“Can I tile directly over this membrane with modified thin-set?”

“What’s the cure time before flood testing?”

“Is this approved for use with foam board substrates?”

Training your inside sales team to respond with precision—backed by manufacturer spec sheets—builds trust and credibility.

Compliance Meets Confidence at the Underlayment Layer

For tile jobs in wet environments, ANSI A118.10 isn’t just a box to check—it’s a critical assurance that the system will hold up under moisture, movement, and time. By supplying underlayments that meet this standard, Buldix and its distribution network give contractors what they need to meet code, pass inspection, and deliver waterproof confidence every time.

When water’s in play, so is risk. Stock membranes that prove you’re building smarter from the bottom up.