Product Definition
Waterproof Backer Board is a high-performance XPS composite construction panel specifically designed for tile backing systems, waterproof wall structures, wet-area construction, and modern interior building applications. The board is prefabricated in the factory using an XPS extruded polystyrene core combined with reinforced upper and lower surface layers made of 1.0mm–1.5mm polymer mortar and alkali-resistant fiberglass mesh.
This advanced composite structure gives the Waterproof Backer Board excellent waterproof performance, lightweight strength, thermal insulation properties, and long-term structural stability, making it an ideal solution for bathrooms, kitchens, shower systems, basements, and moisture-prone construction environments.
Core Technology
As the key structural component of the Waterproof Backer Board, the reinforced polymer mortar layer is primarily composed of low-alkali cement, modified polymer emulsion, quartz sand, and advanced reinforcing materials. To further improve product performance, the formulation has been upgraded with nano-oxide fibers and innovative antimicrobial and anti-mold additives.
This optimized reinforcement technology significantly enhances the bonding strength between the polymer mortar layer and the XPS core material while improving impact resistance and dimensional stability. As a result, the Waterproof Backer Board achieves stronger durability and more reliable long-term performance in waterproof construction systems.
The added antimicrobial and anti-mold technology helps reduce water vapor penetration and moisture absorption, further improving the board’s waterproof and moisture-resistant capabilities. This advanced protection system effectively enhances mold resistance and antibacterial performance, helping create cleaner, safer, and healthier indoor construction environments.
Compared with traditional cement boards and gypsum boards, Waterproof Backer Board offers superior waterproof protection, lighter weight, easier installation, and better thermal insulation performance for modern construction projects.
Suitable for tile underlayment systems, waterproof wall panels, shower installations, floor underlayment, prefabricated construction systems, and moisture-resistant interior applications.
Product Structure
Polymer Mortar: This polymer mortar exhibits exceptionally high bonding strength with the core material, offers robust surface impact resistance, and possesses outstanding moisture-proof, impermeability, and mold-resistance capabilities. Furthermore, it features characteristics such as high-temperature resistance, anti-aging properties, and freeze-thaw resistance, while fully complying with all environmental protection standards. Its structural design—specifically, the lamination of the polymer mortar onto the surface of the core material—significantly enhances the convenience and reliability of subsequent construction processes.
Alkali-Resistant Fiberglass Mesh: This mesh fabric features excellent rigidity and dimensional stability, effectively enhancing the overall toughness of the XPS composite board. Thanks to its superior acid and alkali resistance and robust chemical stability, it ensures that the material remains protected against aging and corrosion throughout its long service life. Utilizing eco-friendly CO2 foaming technology, the product delivers exceptional thermal insulation performance, superior moisture resistance, and extremely high compressive strength. 
Design Advantages
Reliable Waterproof Protection
Provides long-term moisture resistance for wet-area construction and waterproof systems.
Lightweight Construction
The lightweight structure improves installation efficiency and reduces transportation costs.
Strong Structural Stability
Offers excellent load-bearing performance and dimensional stability for wall and flooring systems.
Wide Application Compatibility
Compatible with tile adhesives, waterproof coatings, steel framing systems, and modular construction structures.
Performance Specifications
| Test Items | Metric Requirements |
| Premium Board | Eco-board |
| core Material | Apparent density, kg/m³ | ≥35 | ≥40 |
| Compressive Strength (10% Deformation), kPa | ≥350 | ≥500 |
| Thermal Conductivity (Average Temperature 25°C), W/(m·K) | ≤0.030 |
| Water Absorption (96 h immersion), % | ≤1.5 |
| Dimensional Stability (70±2°C, 48 h), % | ≤1.0 |
| Combustion Performance Classification | No lower than Grade B₁ |
| Oxygen Index (%) | ≥30 |
| Flexural Deformation (mm) | ≥20 |
| Compressive Creep (40°C, 40 kPa, 168 h) (%) | ≤1.5 |
| Water Vapor Permeability Coefficient [ng/(m·s·Pa)] | 1.5~3.5 |
| Total Volatile Organic Compound (TVOC) Emission [mg/(m²·h)] | ≤1.000 |
| Tensile Strength Perpendicular to Board Surface (MPa) | ≥0.40 |
| Foaming Agent Content (%) | The use of chlorofluorocarbon blowing agents is prohibited. |
| Flame Retardant Type (mg/kg) | Hexabromocyclododecane shall not be detected. |
| Smoke Toxicity Class | Attains Quasi-Safety Level 1 (ZA₁) |
| XPS Composite Board | Interlayer Bond Strength (MPa) | ≥0.40 |
| Surface water absorption, g/m² | ≤150 |
| Impermeability | The inner side of the reinforcement layer is not penetrated. |
| Impact Resistance (Number of Impacts) | ≥10 |
| Humidity Deformation (%) | ≤0.07 |
| Shear strength, kPa | ≥250 |
| Bending load, N | Not less than the self-weight of the plate. |
| Free formaldehyde emission, mg/(m²·h) | ≤0.025 |
| Antibacterial Properties | Antibacterial rate ≥ 90% |
| Mold Resistance | Level 0 or Level 1 |
| Compressive Elastic Modulus, MPa | Thickness ≤ 20 mm | ≤0.50 |
| Thickness > 20 mm | ≤1.20 |
| Radioactivity | Internal Radiation Index (IRa) | ≤1.0 |
| External Radiation Index (Ir) | ≤1.3 |
Performance Specifications for XPS Composite Board Thermal and Acoustic Floor Systems:
| Test Items | Metric Requirements |
| Weighted Normalized Impact Sound Pressure Level, dB | ≤65 |
Construction Method
Roof Construction Methods
Method 1:
1. Lay OSB panels flat over the light-gauge steel framing on the roof and secure them using fasteners.
2. Lay XPS composite panels flat over the OSB surface and secure them using fasteners (the XPS composite panels and OSB panels must be laid in a staggered pattern).
3. Seal the joints between the XPS composite panels using Shengtu sealant, then embed a layer of fiberglass mesh tape over the joints. Use a suitable trowel to smooth the sealant, ensuring that both the fiberglass mesh and the fasteners are completely covered; this completes the roof’s waterproofing and thermal insulation layer.
4. Once the sealant has fully dried (approximately 1–2 hours), lay the roofing tiles over the XPS composite panels and secure them in place to complete the project. This method is suitable for various roofing materials, including asphalt shingles, resin tiles, color-coated steel tiles, and glazed tiles.
Method 2:
1. Lay OSB panels flat over the light-gauge steel framing on the roof and secure them using fasteners.
2. Cut XPS composite panels into strips 40–50 mm wide; secure these strips to the OSB panels at intervals of 30 mm. Then, lay full XPS composite panels flat over the strips to create an air cavity, securing them in place with fasteners.
3. Seal the joints between the XPS composite panels using Shengtu sealant, and embed a layer of fiberglass mesh tape over the joints. Use a suitable trowel to smooth the sealant, ensuring that both the fiberglass mesh and the fasteners are completely covered; this completes the roof’s waterproofing and thermal insulation layer.
4. Once the sealant has fully dried (approximately 1–2 hours), lay the roofing tiles over the XPS composite panels and secure them in place to complete the project. This method is suitable for various roofing materials, including asphalt shingles, resin tiles, color-coated steel tiles, and glazed tiles
Exterior Wall External Insulation Construction Methods
1. Clean the substrate surface of the exterior wall, removing any visible impurities;
2. Based on the designated installation location on the exterior wall, determine and verify the dimensions of the XPS composite panels;
3. Proceed with the adhesive installation of the XPS composite panels according to the established positioning; the panels shall be affixed using the “dot-and-frame” method, ensuring an effective bonding area of no less than 50%;
4. Twenty-four hours after the installation of the composite panels is complete, install mechanical anchors to provide supplementary fastening (at a density of 4 to 6 anchors per square meter);
5. Upon completion of the anchor installation, apply a layer of anti-crack mortar reinforced with alkali-resistant fiberglass mesh across the entire surface (to a thickness of 3 mm to 5 mm);
6. Apply exterior wall finishes—such as exterior paints, “True Stone Paint,” or “Water-in-Sand” coatings—to complete the exterior wall surface treatment.
Construction Methods for Interior Insulation of Exterior Walls
1. Clean the substrate surface of the interior wall, removing any visible impurities.
2. Based on the designated installation location for the interior wall, determine and verify the dimensions of the XPS composite panels.
3. Proceed with the adhesive installation of the XPS composite panels according to the established positioning. The panels shall be affixed using the “dot-and-frame” method, ensuring an effective bonding area of no less than 40%. During the bonding process, simultaneously level the wall surface to ensure flatness; bonding mortar must be used to seal any gaps between the panels and the substrate.
4. If mechanical fasteners are required to anchor the XPS composite panels to the substrate wall, the density of fasteners shall be 4 to 6 units per square meter.
5. Use bonding mortar to fill and seal all gaps between the panels, then apply and embed a layer of fiberglass mesh fabric.
6. Reinforce critical areas—such as the four corners of windows—with alkali-resistant fiberglass mesh fabric to prevent cracking.
7. Apply rust-inhibiting paint to the exposed surfaces of the mechanical fasteners to prevent corrosion.
8. Apply a finishing layer consisting of putty followed by paint or wallpaper/wall fabric; alternatively, use tile adhesive to bond ceramic tiles as the final surface finish.
Construction Methods for Bathroom Walls and
1. Complete the leveling of the substrate (concrete surface);
2. Install XPS composite boards and floor drain boards;
3. Lay fiber mesh fabric flat over the joints, then apply Shengtu sealant to fully coat, cover, and smooth the surface;
4. Install the floor drain, and reinforce the floor joints using Shengtu sealant and waterproofing fabric;
5. Upon successful completion of a 48-hour water-retention test, proceed to the next construction stage;
6. Once the sealant has fully dried (approximately 1–2 hours), perform surface finishing and install tiles using the thin-bed method;
7. Clean the wall surface;
8. Use tile adhesive to level the wall surface, bond the Shengtu boards in place, and secure the boards to the substrate wall using mechanical anchors (4 to 6 anchors per square meter);
9. Apply a full coating of 3–5 mm of tile adhesive to the surface of the Shengtu boards, then install wall tiles using the thin-bed method.
Ceiling Installation Methods
1. Install the light-gauge steel keel for the suspended ceiling.
2. Install the XPS composite panels onto the steel keel, securing them in place using threaded fasteners and washers.
3. Seal the joints between the XPS composite panels using Shengtu sealant.
4. Apply fiberglass mesh tape over the joints, then smooth a layer of Shengtu sealant over the mesh tape, as well as over the threaded fasteners and washers.
5. Apply finishing treatments to the ceiling surface, such as skim coating (puttying) and painting.
Basement Construction Methods
1. Level the existing wall surface; then, using cement mortar and mechanical anchors, affix the XPS composite panels to the wall.
2. Level the existing floor surface; then, using cement mortar as an adhesive, lay the XPS composite panels flat on the floor.
3. For the ceiling, refer to standard suspended ceiling construction methods.
4. At the joints, apply fiberglass mesh fabric and Shengtu sealant; use a specialized trowel to scrape the sealant smooth, ensuring it completely covers the fiberglass mesh.
5. Once the sealant has fully dried (approximately 1–2 hours), proceed with the final surface finishing—such as applying putty, followed by painting or hanging wallpaper (or fabric), or using tile adhesive to install ceramic tiles.
Application Scenarios
Waterproof Backer Board is widely used in waterproof construction, tile backing systems, insulation projects, and interior building applications. Its lightweight structure, waterproof performance, thermal insulation capability, and high strength make it suitable for both residential and commercial projects.
Main Application Systems
- Roof insulation systems
- Interior and exterior wall insulation
- Bathroom waterproofing systems
- Basement moisture-proof systems
- Partition walls and suspended ceilings
- Kitchen countertop backing systems
- Swimming pool waterproof systems
Thickness and Recommended Applications
40mm and Above
Suitable for:
- Roof thermal insulation systems
- Building energy-saving projects
- High-performance insulation applications
30mm
Suitable for:
- Basement waterproofing systems
- Insulated wall structures
- Moisture-resistant wall applications
20mm
Suitable for:
- Steel stud wall systems
- Uneven concrete wall leveling
- Pipe encasement structures
- Wall-mounted toilet frame cladding
- Stair tread backing for sintered stone
- Swimming pool tile backing
- Kitchen countertop underlayment
12mm
Suitable for:
- Partition walls
- Room divider systems
- Suspended ceilings
- Decorative wall backing panels
10mm
Suitable for:
- Residential suspended ceiling systems
- Lightweight interior ceiling applications
6mm
Suitable for:
- Decorative feature walls
- Sintered stone slab backing
- Interior cladding systems
- Replacement for plywood or OSB panels
Bathroom Applications
Waterproof Backer Board is commonly used in:
- Floor backing systems
- Wall backing systems
- Shower base systems
- Bathtub surrounds
- Wet and dry separation partitions
- Pipe encasement systems
- Vanity countertop bases
- Toilet backing structures
- Bathroom ceiling systems
Suitable Installation Surfaces
Waterproof Backer Board can be installed on:
- Concrete walls
- Masonry walls
- Steel stud framing systems
- Wood framing systems
- Existing wall renovation surfaces
Project Advantages
- Excellent waterproof performance
- Lightweight and easy installation
- Strong structural stability
- Thermal insulation capability
- Moisture and mold resistance
- Compatible with tile and waterproof systems
- Suitable for wet-area construction projects
