When the job demands robust waterproofing against constant water pressure, from underground basements to potable water tanks, the choice of membrane is critical. Gripset C-1P provides a single-component, fibre-reinforced solution that handles both positive and negative hydrostatic pressure. This flexible cementitious membrane ensures durable protection and exceptional crack bridging, simplifying complex projects with reliable performance.

Why this product exists

Gripset C-1P was engineered to deliver high-performance waterproofing in challenging, continuously wet, and immersed environments. It fills the need for a versatile, one-component solution that resists significant hydrostatic pressure from either side, whether in basement walls, lift pits, or water storage facilities. Its fibre-reinforced composition ensures superior flexibility and crack bridging, making it suitable for concrete and masonry structures subject to movement or exposure.

The numbers that matter

  • Hydrostatic Pressure Resistance: Withstands up to 5 bar positive and 1.5 bar negative pressure. This rating confirms the membrane’s ability to prevent water ingress in subterranean applications like retaining walls and lift pits, where external groundwater or internal forces can compromise structural integrity.
  • Crack Bridging: Achieves ≥0.75 mm crack bridging. This capacity to stretch and maintain integrity over developing substrate cracks minimises the risk of leaks, especially in large concrete pours or masonry construction subject to minor movement.
  • Flexural Strain & Elongation: Offers 37% elongation, classifying it as a Class 1 flexible membrane. This high flexibility allows Gripset C-1P to accommodate structural movement and thermal expansion or contraction without fracturing, ensuring long-term waterproofing performance.
  • Dry Film Thickness: A minimum of 2mm dry film thickness is achieved in two (trowel) or three (roller) coats. This ensures sufficient barrier protection and durability for demanding applications, contributing to its robust pressure resistance and crack bridging capabilities.

What it's like to use

Gripset C-1P is supplied as a light grey powder, simplifying logistics as a single-component product. It mixes easily with water using an electric stirrer, ensuring a homogenous, lump-free consistency. Water ratios can be adjusted for either roller/brush or trowel application, providing flexibility on site. For porous surfaces, pre-dampening is often sufficient, though Gripset OP Primer is recommended for non-porous or burnished concrete to ensure optimal adhesion. Applications require a minimum of two coats by trowel or three by roller to achieve the critical 2mm dry film thickness, with subsequent coats applied in different directions. Crucially, allow 2-4 hours between coats and 7-10 days for full immersion or exposure to water pressure.

Detailing critical areas such as joints, junctions, and penetrations must be completed before membrane application. Use companion products like ELASTOPROOF B50 JOINT BAND or BRW PF TAPE for bond breakers, and ELASTOPROOF COLLARS or RLA MAX SMP 25 for pipe penetrations. Clean tools with water while the product is wet; dried material requires mechanical removal.

Where this product excels

  • Water Storage and Features: Ideal for potable water tanks, retention facilities, swimming pools (under tiles), and decorative water features. Its AS 4020 approval for contact with drinking water makes it a primary choice for sensitive applications, while continuous immersion resistance ensures durability in recreational and storage contexts.
  • Subterranean Structures: Excels in waterproofing basement walls, lift pits, and retaining walls, handling both positive and negative side hydrostatic pressure. This protects against groundwater ingress and soil pressure changes, crucial for the longevity of civil and commercial constructions.
  • Tiled Wet Areas: Provides reliable under-tile waterproofing for internal wet areas like bathrooms and laundries, meeting AS 4858 compliance. It is also suitable for external tiled areas, offering flexibility and crack bridging beneath pavers.
  • Masonry and Concrete Protection: Forms a durable barrier over concrete blocks, brick, and general masonry, protecting against moisture in landscaped areas, slab edges, and earth shelters where traditional treatments may not suffice.

How it fits in a real system

Gripset C-1P frequently serves as the primary waterproofing membrane in critical water containment systems, such as potable water tanks. In these demanding applications, the sequence begins with thorough surface preparation, often involving Gripset 11Y Slurry Primer for concrete, followed by Gripset OP Primer. Essential detailing includes prefabricated corners and Elastoproof Base Collars around penetrations, embedded into a fresh coat of Gripset C-1P. After full cure, the system may be sealed with a complementary top coat like Gripset 2P, ensuring comprehensive, long-term water protection and compliance.

Choose this when

  • Potable Water Contact: When the application requires approval for contact with drinking water, such as internal surfaces of water tanks or storage facilities.
  • Hydrostatic Pressure: When waterproofing against significant positive (up to 5 bar) or negative (up to 1.5 bar) hydrostatic pressure in structures like basements, lift pits, or retaining walls.
  • Flexibility and Crack Bridging: When the substrate may experience movement or minor cracking, requiring a flexible membrane with effective crack bridging capabilities.
  • Single-Component Convenience: When a high-performance, water-mix solution is preferred for ease of use and reduced complexity on site.

Don't use this when

  • Not for: Active Water Leaks: This product will not block running water. Active leaks must first be treated with Gripset C-PLUG.
  • Not for: Exposed Swimming Pools: Gripset C-1P must be tiled over in swimming pools and spas; it is not suitable as an exposed coating.
  • Not for: Extreme Temperatures or Rain: Avoid application when surface or ambient temperatures are below 5°C or above 35°C, or when rain is imminent.
  • Not for: Over Standing Water: Do not apply Gripset C-1P to surfaces with standing water; ensure surfaces are merely damp if not primed.

Gripset C-1P is approved to AS 4020 for contact with potable water, making it a certified choice for drinking water storage. It also complies with AS 4858 for internal wet area applications, providing confidence in its performance for bathrooms, laundries, and other tiled zones. Its technical data confirms robust performance against hydrostatic pressure and superior crack bridging as per ISO 13007-5 standards.

Gripset C-1P vs. Two-Part Cementitious Membranes

Unlike more complex multi-component membranes, Gripset C-1P provides the convenience of a single-component, water-mix solution. This simplifies mixing and reduces potential errors on site, while still delivering high performance. It matches the exceptional flexibility (37% elongation), crack bridging (≥0.75mm), a 2mm dry film thickness, and robust hydrostatic pressure resistance (up to 5 bar positive / 1.5 bar negative) typically expected from two-part systems like Gripset 2P Waterproofing Membrane. Choose Gripset C-1P when the project benefits from the ease of a one-part system without compromising on critical performance metrics.