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.
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.
Engineered for constant water exposure, thermal cycling, and foot traffic loads.
Closed-cell XPS core provides a 100% waterproof barrier — no additional membrane needed.
Insutile® Shower Underlay delivers superior performance across all critical categories:
Complete moisture protection with closed-cell XPS technology.
Closed-cell XPS stops water reaching the subfloor — no damage, no mould, no rot.
Withstands foot traffic and heavy tile loads without deflection.
Rigid XPS withstands foot traffic and tile loads — no deflection, no cracked grout.
Bonds reliably with all standard tile adhesives.
Textured face grips all standard adhesives — tiles stay locked through thermal cycles.
Improves energy efficiency and comfort underfoot.
XPS cuts heat loss through the slab — warmer underfoot, lower energy bills.
Inhospitable to biological growth in wet environments.
Non-porous structure denies water and nutrients — no mould, no mildew beneath the tile.
Consistent performance across temperature and humidity cycles.
Holds its preformed slope through wet-dry cycles — no dips, no pooling water.
Easy to handle and install, reducing labor costs.
Fraction the weight of mortar screeds — faster install, less structural load upstairs.
Standard tools for precise custom fitting around drains and edges.
Cuts cleanly with hand tools — precise fits around drains and complex geometries.
Works seamlessly with linear, point, and sloped drainage systems.
Works with linear, point, and sloped drainage — no design constraints.
Insutile® Shower Underlay — available dimensions and key performance specs:
| Width | Length | Drain |
|---|---|---|
| 900 | 900 | Centre |
| 1000 | 1000 | Centre |
| 1200 | 1200 | Centre |
| 1500 | 1500 | Centre |
| 1000 | 1000 | Offset |
| 1200 | 1200 | Offset |
| 900 | 1200 | Offset |
| 900 | 1500 | Offset |
| 900 | 1800 | Offset |
| 1000 | 1000 | Linear |
| 900 | 1200 | Linear |
| 1000 | 1400 | Linear |
| 1000 | 1800 | Linear |
Engineered for shower-floor loads — ≥ 300 kPa compressive strength holds up under foot traffic, large-format tile, and tile-press cycles without deflection. Keeps the pre-formed slope true through every install.
Compatible with centre, offset, and linear drains — or any custom drain shape on request. The pre-formed slope guides water cleanly to whichever placement and shape you specify.
Ideal for a wide range of applications in residential, commercial, and specialty settings.
Seven essential steps for a successful Insutile® Shower Underlay install. Click a step to view its plate.
Clean and level the structural floor base, ensuring proper slope towards drainage points before laying any boards.
Clean, level base with slope to drain.
Lay out and cut around drains.
Notched-trowel coverage over substrate.
Mechanical fasteners for support.
Waterproof tape + optional fleece layer.
Coating for premium installations.
Standard adhesive on the cementitious face.
For extra waterproofing redundancy, lay a thin white fleece waterproofing layer over the boards during the joint-sealing step. This creates a continuous reinforced membrane across the whole shower floor.
The steps shown are a recommended installation guide. Site conditions, substrates, and finishes vary — always consult a qualified contractor or specifier to confirm the correct method for your project.
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 |
Insutile offers a complete line of specialty construction insulation products:
High-performance tile backer board for wet and dry environments.
Flexible membrane for curved surfaces and complex geometries.
Pre-formed angles for efficient corner and edge protection.
Tapes, meshes, sealants, and fastening systems for complete installations.
Discover how Insutile® Shower Underlay delivers uncompromising waterproof performance for your next project.
Insutile® Shower Underlay provides a rigid, pre-sloped waterproof base for enclosed shower floors. Its closed-cell XPS core won't absorb moisture, holds the fall to the drain through every cycle, and tiles directly without separate membranes.
20 mm standard tray thickness. 30 mm in high-traffic or commercial enclosures where extra compressive strength is needed.
Barrier-free walk-in shower areas demand a tiled base that drains cleanly with no lips or thresholds. Shower Underlay cuts easily around a linear or point drain and stays dimensionally stable through constant water load — no ponding, no cracked grout.
20 mm for most residential walk-ins. 30 mm for heavier commercial traffic or where an extended slope is specified.
Wet rooms take the entire bathroom floor as the drainage plane. Shower Underlay delivers a continuous waterproof base from wall to wall, with the slope pre-built in so the fall stays true after tiling — no mortar-bed puddles, no leaks below.
20 mm is standard. 30 mm for larger spans or commercial wet rooms with heavier traffic.
Steam rooms subject floors to constant condensation plus repeated thermal cycles. Shower Underlay's closed-cell XPS stays dimensionally stable from ambient to steam temperature, and the cement face grips adhesive firmly so tiles don't drift over time.
20 mm minimum. 30 mm where additional thermal performance or heavier tile loads are specified.
For hospitality projects, Shower Underlay speeds fit-out and protects the property from water damage across hundreds of bathroom installs. Its preformed slope eliminates site-mixed screed, and the waterproof core means you can certify each bathroom the same way.
20 mm for standard guest bathrooms; 30 mm for suites or wet-zone-only renovations.
Commercial spa showers see heavy daily use, aggressive cleaning, and constant moisture. Shower Underlay's rigid XPS core carries high-traffic loads, resists biological growth, and stays waterproof across years of continuous operation.
20 mm for typical spa installations. 30 mm in high-traffic commercial bathrooms or where oversized tile demands extra rigidity.
