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Silcor 575 LB: A Product Overview
Silcor 575 LB is a high-solids, one-part polyurethane membrane that delivers proven, Class III performance with no-nonsense, on-site simplicity. It's formulated to be semi-self-levelling, making it fast to apply by roller to horizontal surfaces set to falls. It cures with ambient humidity to form a seamless, monolithic membrane that fully bonds to the substrate, eliminating the risk of water tracking common in sheet systems. Certified to both **AS 4654.1** for external use and **AS/NZS 4858** for internal wet areas, this is the smart, professional choice when you need zero doubt and first-time-right compliance.
>800%
Elongation (AS 4654.1)
Core Features & Specifications
- AS 4654.1 & AS/NZS 4858 Certified: Verified Class III, high-extensibility performance for external non-exposed and internal wet area waterproofing.
- High Performance Elastomer: Achieves exceptional **>800% elongation** and **>5MPa tensile strength**, ensuring it accommodates structural movement and bridges shrinkage cracks.
- One-Part & Humidity Cured: No mixing required, reducing labour and eliminating mix-ratio errors. Cures reliably with ambient humidity.
- Semi Self-Levelling:** Flows out on horizontal surfaces set to falls, providing a smooth finish with simple roller or brush application.
- Low VOC:** Features a Low VOC content of **<110g/L**, improving on-site conditions for applicators.
The Silcor 575 LB Advantage
- Compliance with Zero Doubt: Use a fully certified system. This membrane meets the stringent requirements of Australian Standards, giving you the proof you need to stand behind your work.
- Eliminate Water Tracking: A fully bonded, seamless membrane means water cannot track between the membrane and substrate, removing a key failure point of sheet systems.
- Protect Your Labour Margins: The single-pack, cold-applied formula is job-site ready. No complex mixing or heat, just fast, simple application that saves time.
- Versatile Application: The go-to solution for balconies, podiums, plant room floors, and internal wet areas—one pail, multiple certified applications.
Adheseal tips for using Silcor 575 LB
Scenario: Applying to damp concrete
Potential Outcome: Blistering, delamination, and total system failure. This product is not for damp substrates.
Adheseal Best Practice: Use a moisture meter. For dry concrete (<5% moisture), use Silcor Primer BS. For damp concrete (5% - 6.9%), you *must* use a moisture-tolerant primer like EPOCOTE F100W.
Scenario: Applying in low humidity (e.g., <35% RH)
Potential Outcome: Cure time extends significantly, or the membrane may not cure at all, leaving it soft and uncured.
Adheseal Best Practice: This is a moisture-cured product and *requires* ambient humidity. Do not apply if humidity is below 35% or above 85%.
Scenario: Missing the max recoat time (48 hours)
Potential Outcome: The first coat over-cures, and the second coat will not form a chemical bond, leading to inter-coat delamination and failure.
Adheseal Best Practice: Plan your work. Always apply the second coat within the 12-48 hour window (at 22°C). Do not guess.
Applications in Practice: Trade Scenarios
For Waterproofers (Business Owner): Balcony Waterproofing (AS 4654.1)
The Professional's Challenge
Need a compliant Class III system that is fast to apply, reliable, and won't lead to callbacks on a high-value balcony or podium.
The Adheseal Solution
After priming with Silcor Primer BS (on dry concrete <5% moisture), apply Silcor 575 LB in two cross-directional coats to a total DFT of 1.5mm. Its one-part, semi-self-levelling nature speeds up application. Success means delivering a compliant, fully-bonded system that protects your margin.
Best Practice Note
Before tiling, apply a tie-coat of Silcor 575 LB and broadcast to refusal with 0.5-1.0mm quartz sand. This is mandatory for a first-time-right tile bond.
For Builders (On-Site Installer): Internal Wet Areas (AS 3740)
The Professional's Challenge
Ensuring a seamless, leak-proof membrane in a shower base before screeding, with no room for error or delays.
The Adheseal Solution
Detail all internal corners and penetrations with Silcor LM PU Sealant. Prime the substrate, then apply Silcor 575 LB in two coats to 1.5mm DFT. Its liquid application creates a seamless, monolithic tank, perfectly bonding to the substrate. Success means a fast, no-fuss install that passes flood testing first time.
Best Practice Note
Ensure falls to drainage are a minimum 1:80 in showers. The membrane must be applied *before* the screed (if over screed, different rules apply).
For Specifiers/Engineers: Plant Room Floors
The Professional's Challenge
Specifying a durable, chemical-resistant, and fully bonded membrane for a critical plant room floor with multiple penetrations.
The Adheseal Solution
Specify Silcor 575 LB. Its PU chemistry, >5MPa tensile strength, and seamless liquid application provide robust protection that is easily detailed. When topped with Silcor Top Coat 75, it becomes a durable, UV-stable, and foot-trafficable system. Success means specifying a proven, reliable system that removes risk.
Best Practice Note
Ensure all penetrations are detailed with a 15x15mm fillet of Silcor LM PU Sealant prior to the membrane application to ensure a robust seal.
Frequently Asked Questions
Is SILCOR 575 LB compliant with Australian Standards?
Yes, it is fully certified. SILCOR 575 LB is a Class III High Extensibility membrane compliant with **AS 4654.1-2012** for external non-exposed applications, and also with **AS/NZS 4858-2004** for internal wet areas.
What is the correct DFT (Dry Film Thickness) for SILCOR 575 LB?
The correct DFT depends on the application. For AS 4654.1 and AS 4858 compliance, a minimum DFT of 1.5mm is typically required, applied in at least two coats. Always check your project specification or contact your GCP representative for warranty-specific DFTs.
Can I apply SILCOR 575 LB on a damp or 'green' concrete slab?
Not directly. SILCOR 575 LB must be applied to a dry substrate. However, you can use it on green or damp concrete (up to 6.9% moisture content) if you first prime the substrate with a moisture-tolerant primer like EPOCOTE F100W.
What primers can I use with SILCOR 575 LB?
Primer selection depends on the substrate and moisture content. For dry concrete (<5% moisture), use SILCOR Primer BS. For green or damp concrete (up to 6.9% moisture), use EPOCOTE F100W. For metals and PVC, use EPOCOTE F100W Clear or SILCOR Primer BS after correct preparation.
Applications & Benefits
| Application / Use Case | Key Benefit | Primary Trades |
|---|---|---|
| External Balconies, Podiums, Roof Decks | Certified Class III (AS 4654.1), seamless, fully bonded system. | Waterproofers, Builders |
| Internal Wet Area Floors | Certified Class III (AS/NZS 4858) for monolithic tanking under tiles/screeds. | Waterproofers, Tilers, Builders |
| Plant Room Floors and Bunds | High tensile strength, seamless, and fully bonded. | Remedial Contractors, Builders |
| Green Roofs & Landscaped Decks | Robust, fully bonded membrane (requires protection/root barrier). | Waterproofers, Landscapers |
Applying SILCOR 575 LB: Enhanced Protocols & Best Practices
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Step 1: Substrate Preparation
Substrate must be sound (min 20 MPa), smooth, clean, and dry. Remove all dust, laitance, oil, curing compounds, and contaminants by grinding, shot blasting, or high-pressure water blasting. Repair all defects.
Pro Tip: Check moisture content. For SILCOR 575 LB, it MUST be <5.0% unless using EPOCOTE F100W primer. -
Step 2: Detailing (Corners, Joints & Cracks)
All detailing must be done *before* priming.
Internal Corners & Penetrations
Install a bond breaker fillet of SILCOR LM PU Sealant (min. 12x12mm internal, 15x15mm external). Allow to cure for 12 hours.
Joints & Cracks
Chase non-moving joints/cracks, prime, and fill with SILCOR LM PU Sealant over a bond breaker tape. For movement joints, consult your GCP representative.
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Step 3: Priming
Prime all substrates with the appropriate GCP primer. Apply membrane within the primer's recoat window.
Pro Tip: To avoid pinholes from concrete outgassing, prime substrates when the temperature is stable or falling (e.g., afternoon). -
Step 4: Membrane Application (Min. 2 Coats)
Mix pail thoroughly with a drill (max 600 RPM). Apply membrane using a 10-14mm nap roller in two (or more) cross-directional coats to achieve the specified DFT (e.g., 1.5mm total).
Timing: Min. Recoat Time: 12 hours. Max. Recoat Time: 48 hours (at 22°C/60%RH). Ready for flood testing: 48 hours.Pro Tip: Use a Wet Film Thickness (WFT) gauge every 2m² to ensure you are applying enough material to meet the specified DFT. -
Step 5: Tie-Coat for Tiling / Toppings
If direct-sticking tiles or applying bonded screeds, a tie-coat is **mandatory**. Between 12-48 hours of the final membrane coat, apply a fresh coat of SILCOR 575 LB at 0.95 kg/m². Immediately broadcast to refusal (120% coverage) with 0.5-1.0mm clean, dry quartz sand. Allow 24h cure, then vacuum off excess sand.
Limitations & Safety
Product Limitations
Environmental Conditions: Do not apply if ambient humidity is below 35% or above 85%. Do not apply if rain is imminent.
Substrate: Not for negative pressure applications. Not to be installed on damp or contaminated substrates (see primer requirements).
Exposure: Not suitable for heavy foot or vehicle traffic unless protected. For UV stability or light foot traffic, must be overcoated with SILCOR Top Coat 75.
Application: This is a semi-self-levelling product. It is *not* suitable for vertical or ramped surfaces as it will run.
Safety & Handling Requirements
Personal Protective Equipment
Wear protective gloves (Nitrile or Rubber), chemical-resistant clothing, and safety glasses with side shield protection.
Ventilation Requirements
Harmful if inhaled. Use only outdoors or in a well-ventilated area. If exposure limits may be exceeded or ventilation is poor, wear an approved respiratory protection (NIOSH, CEN, etc.).
Fire & Handling Precautions
Combustible liquid. Keep away from heat, sparks, open flames, and hot surfaces. No smoking.
Emergency First Aid
Eyes:
Causes serious eye damage. Rinse cautiously with water for several minutes. Remove contact lenses. Continue rinsing. Immediately call a POISON CENTER/doctor.
Skin:
Causes severe skin burns. Take off immediately all contaminated clothing. Rinse skin with water or shower. Wash contaminated clothing before reuse.
Inhaled:
May cause allergy or asthma symptoms. Remove person to fresh air. If experiencing respiratory symptoms, call a POISON CENTER/doctor.
Swallowed:
Rinse mouth. Do NOT induce vomiting. Immediately call a POISON CENTER/doctor.
Seek medical attention immediately in all cases of serious exposure.
SILCOR 575 LB Substrate Guide
Concrete, Screeds, Renders (Dry)
Surface Preparation
Structurally sound (min 20 MPa), smooth, clean, and dry. Remove all laitance, dust, curing compounds, or contaminants. Moisture content MUST be <5.0%.
Primer Requirements
Primer Required
Apply one coat of primer.
SILCOR Primer BSConcrete (Damp or Green)
Surface Preparation
As per dry concrete, but moisture content can be between 5.0% and 6.9%.
Primer Requirements
Moisture Tolerant Primer Required
Use only a moisture-tolerant epoxy primer.
EPOCOTE F100W (Clear or Grey)Compressed Fibre Cement (CFC) & Cement Composite (CCS) Sheet
Surface Preparation
Install per manufacturer's directions. Must be clean, dry, and free of all surface sealers, coatings, or dust.
Primer Requirements
Primer Required
SILCOR Primer BS is recommended for best penetration on CCS (e.g., Scyon).
SILCOR Primer BS or EPOCOTE F100WMetals (Steel, Aluminium) & Plastics (PVC, ABS)
Surface Preparation
Remove all corrosion, oil, and grease. Abrade or garnet blast to SA 2.5 near white metal. Solvent wipe with Xylene or MEK and prime within 30 minutes to prevent oxidation.
Primer Requirements
Primer Required
Apply one coat of primer.
EPOCOTE F100W Clear or SILCOR Primer BS- Choosing a selection results in a full page refresh.