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Attention: This product is special order only, delivery of product can take an estimated 1 week or more. Please contact us directly for more information.
Use Silcor 575 LB for: Certified Class III waterproofing of balconies, podiums, roof decks, plant rooms, internal wet areas, and green roof systems (horizontal applications only).
Silcor® 575 LB is a premium, one-part, liquid-applied polyurethane waterproofing membrane engineered for robust, long-lasting protection on horizontal substrates set to falls. Formulated with high solids (91%) and low VOCs (<110 g/L), this moisture-curing membrane provides a safer and more environmentally considerate solution for demanding waterproofing projects across Australia. Its key advantage lies in its **dual Class III certification**, meeting the high extensibility requirements of both **AS 4654.1-2012** (External Non-Exposed) and **AS/NZS 4858-2004** (Internal Wet Areas), ensuring compliance for critical applications like balconies, podiums, plant rooms, and bathrooms. The **semi self-levelling** consistency simplifies application by roller or brush, flowing out to a smooth, seamless finish. Once cured, Silcor 575 LB forms a tough, highly flexible (>800% elongation) and strong (>5 MPa tensile strength) elastomeric membrane that fully bonds to correctly primed substrates, eliminating water tracking.
Primer Information: Correct substrate priming is crucial for system performance. For dry (<5% moisture) concrete, masonry, CFC/CCS, timber, metals, PVC, and ABS, use **Silcor® Primer BS** (solvent-based PU) or **EPOCOTE™ F100W Clear** (water-based epoxy). For green or damp (5%-6.9% moisture) concrete/masonry, or W/R plasterboard, use **EPOCOTE™ F100W Clear or Grey**. Highly porous concrete may benefit from EPOCOTE F100W Grey. Refer to specific primer PDS for application rates and recoat windows.
Cure Time: Curing is dependent on ambient temperature and humidity (requires 35-85% RH). At 23°C / 60% RH, Silcor 575 LB becomes tack-free in approx. 4 hours, rain resistant in 2 hours, ready for minimum recoat in 12 hours (max 48 hours), and ready for flood testing or topping in **48 hours**. Cooler temperatures or lower humidity will extend these times significantly.
Coverage / DFT: Achieve the specified Dry Film Thickness (DFT) for your project (typically 1.3mm or 1.5mm minimum depending on area/warranty). This requires careful application rate control. For example, a 1.5mm DFT requires a total application rate of approx. **2.35 kg/m²**, yielding roughly 9.4 m² coverage per 22kg pail. Always confirm required DFT with your GCP Project Specification and use a Wet Film Thickness (WFT) gauge during application.
Application Temperature Range: Apply when substrate and ambient temperatures are between 5°C and 35°C and stable or falling (to minimise substrate outgassing). Ensure substrate temperature is at least 3°C above the dew point.
Chemical Properties: Based on durable **polyurethane chemistry**, Silcor 575 LB is free from bitumen and tar, preventing bleeding or staining. It exhibits good resistance to water immersion, bleach, and detergents as per Australian Standard testing requirements.
Key Features of Silcor® 575 LB
- Certified Class III Performance: Meets high extensibility requirements of AS 4654.1 (External Non-Exposed) & AS/NZS 4858 (Internal Wet Areas) for ultimate compliance peace of mind.
- High Strength & Flexibility: Combines high tensile strength (>5 MPa) with exceptional elongation (>800%) to accommodate structural movement and bridge shrinkage cracks effectively.
- Seamless & Fully Bonded: Creates a monolithic, liquid-applied barrier with no vulnerable seams or laps, preventing water ingress and under-membrane water tracking.
- Semi Self-Levelling Application: Flows out smoothly on horizontal surfaces set to falls, simplifying application and creating an ideal base for subsequent finishes.
- One-Part & Moisture Cured: No complex mixing required on site; cures through reaction with ambient humidity (requires 35-85% RH).
- Low VOC & Cold Applied: Contains <110 g/L VOCs for reduced site EH&S concerns. No flames or heat required for application.
- Polyurethane Chemistry: Durable, elastomeric, and free from bitumen or tar, ensuring no bleeding or staining issues.
Why Choose Silcor® 575 LB:
- Compliance Assurance: Specify and install with confidence knowing it meets the stringent requirements of key Australian waterproofing standards.
- Long-Term Durability: High physical properties ensure a robust, long-lasting waterproofing solution capable of handling typical building stresses.
- Application Efficiency (Horizontal): Semi self-levelling nature saves time and effort in achieving a smooth, uniform membrane on horizontal decks and floors.
- System Compatibility: Integrates with GCP primers (Silcor Primer BS, Epocote F100W), detailing sealant (Silcor LM PU), and top coat (Silcor Top Coat 75) for a complete system solution.
- Reduced Risk: Seamless, fully bonded application minimises common failure points associated with sheet membranes or improperly bonded systems.
When to Choose Silcor® 575 LB versus Alternatives:
- Choose Silcor 575 LB over Cementitious Membranes when: High flexibility, crack bridging (>1mm), and compliance with AS 4654.1 / AS 4858 Class III extensibility are required (cementitious are rigid). Ideal for substrates with potential movement.
- Choose Silcor 575 LB over Bituminous Membranes (Sheet/Liquid) when: A seamless, liquid-applied system is preferred, complex detailing is involved, potential bitumen bleed/staining is a concern, or specific PU performance is needed.
- Choose Silcor 575 LB over Acrylic Membranes when: Superior toughness, higher tensile strength, better resistance properties, or compliance with AS 4654.1 / AS 4858 Class III are paramount, especially under screeds or toppings.
- Consider other options when: UV stability is required without a top coat (use UV-stable membranes), application is on vertical surfaces (use Silcor 575 HB or other non-sag membranes), negative hydrostatic pressure exists, permanent water immersion is expected (check specific product suitability), or application humidity is outside 35-85% RH range.
Trade-Specific Applications for Silcor® 575 LB:
For Waterproofing Contractors:
- Compliant Applications: Apply to meet AS 4654.1 Class III (External Non-Exposed - e.g., under screeds/pavers on balconies/podiums) and AS/NZS 4858 Class III (Internal Wet Areas - e.g., bathroom floors).
- Technique: Utilise semi self-levelling properties for efficient horizontal application. Ensure correct DFT using WFT gauge. Strictly follow priming, detailing (Silcor LM PU sealant), and tie-coat procedures (if required for bonded toppings).
- System Knowledge: Must understand humidity/temperature effects on cure, recoat windows, and requirements for top coating (Silcor Top Coat 75) or protection (Protectoboard/Rapid-Drain).
- Performance Benefits: Delivers certified, high-performance results demanded by specifications; reliable system components.
For Builders:
- Project Coordination: Ensure substrate quality (falls, smoothness, dryness) meets requirements before waterproofing commences. Coordinate correct primer selection based on substrate moisture content.
- System Understanding: Recognise the need for protection (top coat or coverings) and the mandatory tie-coat procedure if direct-stick tiles or bonded screeds are planned over the membrane.
- Quality Assurance: Verify minimum DFT application and adherence to AS 3740 / AS 4654.2 installation requirements by the waterproofing applicator.
- Performance Benefits: Provides a compliant, durable waterproofing layer for critical horizontal areas, reducing defect risks.
For Architects / Specifiers:
- Specification: Specify Silcor 575 LB for horizontal applications requiring AS 4654.1 Class III or AS/NZS 4858 Class III compliance. Detail required DFT based on GCP recommendations for area and warranty.
- System Design: Ensure correct falls (min 1:100), drainage, substrate preparation, primer selection, detailing (Silcor LM PU), tie-coat (if needed), and protection/top coat (Silcor Top Coat 75, Protectoboard, Rapid-Drain) are included in the specification.
- Material Properties: Utilise data on high elongation, tensile strength, low VOC content, and chemical resistance in design considerations.
- Performance Benefits: Certified compliance, robust physical properties, seamless barrier, system solution from GCP.
Application Information
- Required Tools: 10-14mm nap non-shedding roller or brush, mixing pail, minimum 650W variable speed drill (<600 RPM) with paddle/Jiffy mixer, Wet Film Thickness (WFT) gauge, standard cleaning supplies (xylene for cleanup).
- Trade-Specific Tips: Applicators: Monitor temperature, humidity, and dew point closely. Apply when substrate temp is stable or falling. Check WFT frequently. Ensure correct primer and recoat window adherence. Tilers/Screed Layers: Confirm mandatory tie-coat (membrane + sand broadcast) has been correctly applied by the waterproofer before attempting to bond tile adhesive or screeds directly.
- Common Issues and Solutions: Pin-holing: Often caused by substrate outgassing - prime when substrate temp is stable/falling, ensure primer is pinhole-free before applying membrane. Slow Cure: Low temperature or low humidity (<35% RH) - ensure conditions are within range, allow extended cure times. Poor Adhesion: Incorrect/failed priming or substrate contamination - reprepare and prime correctly. Runs on Slopes: Product is semi self-levelling - not suitable for vertical or steeply sloped areas (use Silcor 575 HB).
Storage and Shelf Life
- Storage Requirements: Store pails upright in original unopened packaging between 15°C and 25°C. Must be kept under cover, protected from heat sources, ignition, moisture, frost, and direct sunlight.
- Shelf Life Information: 9 months from the date of manufacture when stored correctly. Check pail for expiry date before use.
- Temperature Considerations: Avoid storing in extreme hot or cold conditions which can affect product consistency and shelf life. Bring product to within application temperature range before use.
Certifications and Compliance
- AS 4654.1-2012 Class III: Certified High Extensibility membrane suitable for external non-exposed waterproofing applications installed to AS 4654.2-2012.
- AS/NZS 4858-2004 Class III: Certified High Extensibility membrane suitable for internal wet area waterproofing installed to AS 3740-2021.
- Low VOC: VOC content <110 g/L, contributing positively towards indoor air quality credits in green building schemes.
Frequently Asked Questions About Silcor® 575 LB
Q: Is Silcor 575 LB UV resistant? Can I leave it exposed on a balcony?
A: No, Silcor 575 LB is not UV stable on its own. If it will be left exposed to sunlight (e.g., on a balcony or podium), it MUST be overcoated with Silcor® Top Coat 75 (minimum 2 coats) for UV protection and to provide a trafficable surface. Alternatively, it must be covered with pavers, decking, screeds, tiles, or soil (for green roofs).
Q: Can I apply tile adhesive or a bonded screed directly onto cured Silcor 575 LB?
A: No, direct bonding of cementitious adhesives or screeds is not recommended. A mandatory 'tie-coat' procedure MUST be followed. This involves applying another coat of Silcor 575 HB or LB membrane, broadcasting fully with specified sand, allowing to cure, and removing excess sand before applying the bonded system.
Q: What is the minimum fall required for a substrate before applying Silcor 575 LB?
A: For general external areas like balconies and podiums, a minimum fall of 1:100 to drainage outlets is required. For internal shower areas, the minimum fall required is 1:80. The substrate must not allow water to pond, other than minor residual surface tension.
Q: What is the required thickness (DFT) for Silcor 575 LB?
A: The minimum required Dry Film Thickness (DFT) depends on the application area and the warranty period desired. Typical minimums are 1.3mm or 1.5mm DFT. Always refer to the project-specific GCP Specification or contact your GCP representative to confirm the required DFT for your job.
Q: Can Silcor 575 LB be used on vertical surfaces like retaining walls?
A: No, Silcor 575 LB is semi self-levelling and designed specifically for horizontal surfaces set to falls. It will run or sag if applied vertically. For vertical applications, use a non-sag polyurethane membrane like Silcor® 575 HB or similar specified product.
Q: What primer should I use if the concrete is damp?
A: If the concrete moisture content is between 5.0% and 6.9% (or visibly damp but no standing water), you must use EPOCOTE™ F100W (Clear or Grey) epoxy primer. If moisture content is above 6.9%, the substrate is too wet and must be allowed to dry further before priming.
Use Silcor® 575 LB for:
- Balconies & Terraces: Compliant waterproofing under tiles, screeds, or pavers on pods (use tie-coat or Top Coat 75 as required).
- Podiums & Roof Decks: Robust membrane layer for non-exposed or protected roof deck applications (part of system with protection/drainage/top coat).
- Green Roofs & Landscaped Decks: Waterproofing layer beneath drainage cells, soil, and plantings (ensure protection layer used).
- Plant Room Floors & Bunds: Seamless, chemical resistant (check specific chemicals) waterproofing for mechanical areas.
- Internal Wet Areas: Certified Class III membrane for bathroom floors, laundries under screeds or tiles (requires tie-coat for direct stick).
- General Horizontal Waterproofing: Non-exposed external areas requiring high-performance, compliant liquid membrane set to falls.
Why Use Silcor® 575 LB for:
- Meeting Australian Standards: Provides certified Class III performance against AS 4654.1 and AS/NZS 4858 for project compliance.
- Durable Long-Term Protection: High tensile strength and elongation ensures resilience against movement and cracking for extended service life.
- Preventing Leaks: Creates a seamless, fully bonded barrier that eliminates vulnerable joints and prevents water tracking beneath the membrane.
- Simplified Horizontal Application: Semi self-levelling properties aid in achieving a smooth, uniform finish on correctly sloped surfaces.
- System Assurance: Part of a complete system with compatible GCP primers, sealants, protection, and top coats for reliable performance.
- Healthier Application Environment: Low VOC formulation reduces exposure risks for applicators and building occupants during installation.
How to apply Silcor® 575 LB:
- Surface Preparation: Ensure substrate meets quality requirements (sound, smooth, clean, dry, correct falls). Repair defects. Chase joints/cracks. Remove all contaminants. Allow adequate cure times for concrete/renders.
- Detailing: Apply bond breaker fillets (min 12x12mm or 15x15mm) of Silcor® LM PU Sealant to internal corners and penetrations per AS 3740 / AS 4654.2. Treat joints and cracks appropriately (sealant/bond breaker tape). Allow sealant to cure (min 12 hours).
- Priming: Select and apply the appropriate GCP primer (Silcor Primer BS or Epocote F100W) based on substrate type and moisture content. Apply evenly, avoiding pooling. Observe primer recoat windows (refer to primer PDS). Address any primer pin-holing before proceeding.
- Mixing: Thoroughly mix the Silcor 575 LB pail using a low-speed drill (<600 RPM) and paddle mixer, avoiding air entrapment.
- First Coat Application: Apply the first coat evenly by 10-14mm nap roller or brush to the primed substrate at the required rate to achieve approx. half the total specified DFT. Check WFT regularly.
- Second Coat Application: Allow the first coat to cure to minimum recoat time (12 hours at 23°C/60%RH). Apply the second coat, typically perpendicular to the first, at the required rate to achieve the total specified DFT (e.g., 1.3mm or 1.5mm). Continuously monitor WFT.
- Curing: Allow the membrane to cure fully (minimum 48 hours at 23°C/60%RH) before flood testing, applying protection, or proceeding with subsequent layers. Ensure humidity is between 35-85% RH during cure.
- Tie Coat (If Required): If applying direct-stick tiles or bonded screeds/toppings, apply the mandatory tie coat (additional Silcor membrane coat blinded with sand) between 12-48 hours after the final membrane coat. Allow tie coat to cure (min 24 hours) and remove excess sand.
- Protection / Top Coat (If Required): Install specified protection (Protectoboard, Rapid-Drain) or apply Silcor Top Coat 75 (min 2 coats) if the membrane is to be left exposed or subjected to traffic.
- Clean Up: Clean tools immediately with xylene solvent while product is wet. Cured material requires mechanical removal.
Silcor® 575 LB limitations:
- Not UV Stable: Must be protected from sunlight by Silcor Top Coat 75 or suitable coverings (screed, tiles, pavers, soil etc.).
- Horizontal Use Only: Semi self-levelling nature makes it unsuitable for vertical or steeply sloped surfaces.
- Not Trafficable Without Top Coat: Cannot withstand direct foot or vehicle traffic unless protected by Silcor Top Coat 75 or appropriate wearing course (pavers, screed).
- Bonded Toppings Require Tie Coat: Mandatory tie-coat procedure (membrane + sand) needed before applying cementitious adhesives or bonded screeds.
- Not for Negative Pressure: Cannot be used on the inside face against external water pressure.
- Not for Immersion: Not recommended for lining water tanks or areas of permanent ponding. Ensure adequate falls (min 1:100).
- Substrate Condition Critical: Requires dry (or within limits for Epocote primer), clean, sound, and correctly primed substrate.
- Humidity Dependent Cure: Requires relative humidity between 35% and 85% for proper curing. Cure times vary significantly with conditions.
- Shelf Life: Note the 9-month shelf life and specific storage requirements (15-25°C).
Safety precautions when using Silcor® 575 LB:
- Personal Protective Equipment (PPE): Wear impervious gloves (e.g., nitrile), safety glasses/goggles, and suitable protective clothing. Avoid skin and eye contact. Refer to the Safety Data Sheet (SDS).
- Ventilation: Ensure adequate ventilation during application and cure, especially in enclosed or semi-enclosed areas, even though it's low VOC.
- Handling: Avoid eating, drinking, or smoking while handling. Wash hands thoroughly after use. Keep out of reach of children.
- First Aid: Consult the SDS for details. Generally: Eyes: Flush immediately with plenty of water for 15 mins, seek medical attention. Skin: Remove contaminated clothing, wash skin thoroughly with soap and water. Inhalation: Move to fresh air, seek medical attention if symptoms persist. Ingestion: Do NOT induce vomiting, seek immediate medical attention.
- Disposal: Dispose of cured waste and empty containers according to local authority regulations. Do not discharge into drains or waterways.
Silcor® 575 LB can be used on the following substrates:
- Concrete: Structurally sound (min 20MPa), fully cured (14-28 days), smooth finish (steel trowel/light float), clean, dry (<5% or <6.9% moisture depending on primer). Requires appropriate GCP primer (Silcor Primer BS or Epocote F100W).
- Concrete Block Masonry: Reinforced, core-filled, sound blocks with flush-pointed joints. May require fairing coat if porous. Requires primer.
- Screeds, Toppings, Renders: Sound, stable, min 20MPa compressive strength, cured min 3 days (depends on type). Requires primer.
- Compressed Fibre Cement (CFC) Sheet: Installed to manufacturer's specs, clean, dry, free of sealers. Requires primer (Silcor Primer BS recommended for penetration).
- Cement Composite Sheet (CCS) & W/R Plasterboard: Installed correctly, clean, dry, free of sealers. CCS requires careful priming with Silcor Primer BS. W/R Plasterboard requires Epocote F100W primer.
- Water Resistant Plywood / Structural Timber: Must be water-resistant grade, structurally sound, clean, dry. Requires primer.
- Metals: Prepared steel, aluminium, zinc/galvanising, copper, stainless steel. Must be cleaned, abraded, solvent wiped, and primed promptly (Epocote F100W or Silcor Primer BS, check PDS).
- Plastics (PVC, ABS): Clean, solvent wiped (MEK), requires primer (Epocote F100W or Silcor Primer BS). Test adhesion.
- Aerated Autoclaved Concrete (AAC): Must be rendered first with high-strength render to seal surface. Render must be cured and dry before priming.
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