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Wet Room Essential

Insutile®
Shower Underlay

Waterproof Tile Backer Boards for Shower Floors

High-performance XPS foam boards specifically engineered for shower floor applications — rigid, fully waterproof, and tile-ready, withstanding constant water exposure and foot traffic.

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What is Insutile® Shower Underlay?

Shower-Grade Waterproof Substrate

Insutile® Shower Underlay is a specialized tile backer board engineered for the unique demands of shower floor installations. The board provides a rigid, dimensionally stable substrate that bonds reliably with all standard tile adhesives and supports ceramic, porcelain, mosaic, and natural stone tile finishes.

Its closed-cell XPS core is 100% waterproof, providing an intrinsic moisture barrier that eliminates the need for separate waterproofing membranes while maintaining excellent structural integrity under constant water exposure and foot traffic loads.

Shower-Grade Durability

Engineered for constant water exposure, thermal cycling, and foot traffic loads.

Intrinsic Waterproofing

Closed-cell XPS core provides a 100% waterproof barrier — no additional membrane needed.

Insutile Shower Underlay Product

Key Features & Benefits

Insutile® Shower Underlay delivers superior performance across all critical categories:

100% Waterproof Core

100% Waterproof Core

Complete moisture protection with closed-cell XPS technology.

100% Waterproof Core

The closed-cell XPS foam core creates an impermeable barrier that prevents water penetration into subfloors and structural elements. This is critical for shower underlays where moisture exposure is constant and prolonged, protecting against costly water damage and mold growth that could compromise the entire wet room installation.

High Compressive Strength

High Compressive Strength

Withstands foot traffic and heavy tile loads without deflection.

High Compressive Strength

The XPS foam provides exceptional compressive strength that resists deformation under bathroom traffic and large tile weights. This prevents the floor from flexing or settling, which could crack tiles, grout, and membranes. The rigid support is essential for maintaining the pre-sloped gradient essential to proper drainage in walk-in showers and wet rooms.

Excellent Tile Adhesion

Excellent Tile Adhesion

Bonds reliably with all standard tile adhesives.

Excellent Tile Adhesion

The foam surface texture provides superior mechanical grip for tile adhesives, ensuring tiles remain locked in place through moisture cycles and temperature fluctuations. Reliable adhesion is vital in shower environments where thermal cycling and constant moisture exposure can stress traditional floor bonds, preventing tile lippage and movement that lead to joint failures.

Thermal Insulation

Thermal Insulation

Improves energy efficiency and comfort underfoot.

Thermal Insulation

XPS foam provides inherent thermal insulation properties that reduce heat loss through shower floor slabs. This improves overall building energy efficiency and creates a warmer, more comfortable underfoot experience during bathing, particularly important in ground-floor wet rooms or installations over unconditioned spaces. Better warmth also reduces tile shock on sensitive skin.

Mold & Mildew Resistant

Mold & Mildew Resistant

Inhospitable to biological growth in wet environments.

Mold & Mildew Resistant

The non-porous closed-cell structure of XPS foam prevents water retention and nutrient absorption that biological organisms require to thrive. In shower underlays, this inert material resists mold and mildew colonization better than traditional sand and cement screeds, maintaining hygiene and structural integrity even in permanently wet conditions beneath shower drains and slopes.

Dimensionally Stable

Dimensionally Stable

Consistent performance across temperature and humidity cycles.

Dimensionally Stable

Unlike traditional sand/cement screeds that expand and contract with moisture and temperature swings, XPS foam maintains its dimensions reliably through the extreme wet-dry cycles of shower environments. This dimensional stability preserves the critical pre-sloped gradient, preventing floor movement that would destroy waterproof membranes and create low spots where water pools instead of draining.

Lightweight

Lightweight

Easy to handle and install, reducing labor costs.

Lightweight

Pre-molded XPS sheets weigh a fraction of traditional mortar screeds, dramatically reducing handling burden on installation crews. This lightweight advantage accelerates project timelines and reduces installation labor expenses, while also minimizing structural load impacts on supporting elements. For multi-story buildings, the weight savings are particularly valuable in upper-floor wet room installations.

Easy to Cut On-Site

Easy to Cut On-Site

Standard tools for precise custom fitting around drains and edges.

Easy to Cut On-Site

The foam material cuts cleanly with simple hand and power tools, allowing installers to precisely fit around drain outlets, sloped edges, and complex geometries without requiring specialized equipment. This on-site flexibility minimizes waste, ensures tight integration with drainage systems, and reduces installation time compared to rigid preformed bases that require custom ordering for specific shower configurations.

Compatible with All Drain Types

Compatible with All Drain Types

Works seamlessly with linear, point, and sloped drainage systems.

Compatible with All Drain Types

The flexible XPS foam adapts to all modern drainage configurations, from point drains to linear channel systems to fully sloped wetroom layouts. This universal compatibility eliminates design constraints, allowing architects and installers to choose drainage solutions based on aesthetic and performance criteria rather than base material limitations. Pre-sloped variants accommodate any slope requirement for optimal water runoff.

Available Sizes

Insutile® Shower Underlay is manufactured in a range of thicknesses and standard dimensions:

Thickness (mm) Width (mm) Length (mm) Weight (kg) Coverage (m²)
612002400——
1012002400——
1212002400——
1512002400——
2012002400——
2512002400——

Where Insutile Performs

Ideal for a wide range of shower and wet room applications:

Shower Enclosure Floors

Purpose-built substrate for enclosed shower floor installations.

Walk-In Shower Bases

Ideal for open walk-in shower designs requiring waterproof substrates.

Wet Room Floors

Complete waterproof flooring solution for fully wet room environments.

Steam Room Floors

Handles extreme humidity and temperature in steam room applications.

Spa Shower Areas

Commercial-grade performance for spa and wellness shower facilities.

Hotel Bathroom Floors

Specification-grade substrate for premium hospitality bathroom projects.

Residential Bathroom Renovations

Lightweight profile ideal for retrofit and renovation projects.

Commercial Washroom Floors

Durable waterproof solution for high-traffic commercial washrooms.

How to Install Insutile Shower Underlay

Seven essential steps for successful shower underlay installation:

1

Substrate Preparation

Clean and level the structural floor base, ensuring proper slope towards drainage points.

2

Positioning & Fitting

Lay out boards and cut to fit around drains, edges, and penetrations with standard tools.

3

Adhesive Application

Apply adhesive using a notched trowel for full coverage and proper bonding.

4

Fixing

Secure boards to substrate with mechanical fasteners as specified for structural support.

5

Joint & Edge Sealing

Seal all joints and edges with waterproof tape or sealant to prevent water ingress.

6

Waterproofing

Apply waterproofing coating if additional protection is desired for premium installations.

7

Tiling

Install tile with standard adhesive on the waterproof cementitious surface.

How We Compare

Insutile® Shower Underlay outperforms alternatives across all key metrics:

Property Insutile® Shower Underlay Standard Cement Board Plywood + Membrane Sand-Cement Screed
Waterproof Core ✓ ✗ ✗ ✗
Tile-Ready Surface ✓ ✓ ✗ ✗
Compressive Strength High (400+ kPa) Medium Low High
Mold Resistance ✓ Partial ✗ Partial
Thermal Insulation ✓ ✗ ✗ ✗
Installation Speed Fast Fast Slow Slow
Weight Lightweight Lightweight Heavy Very Heavy

Explore Our Range

Insutile offers a complete line of specialty construction insulation products:

Ready to Transform Your Shower Floor?

Discover how Insutile® Shower Underlay delivers uncompromising waterproof performance for your next project.

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