Flexible Polymeric Membrane

Product Description

BETEC FLX 120 is a fast curing, two-pack, polymer modified, tough cementicious waterproofing membrane. It is reinforced with specially graded synthetic fibre. When blended, BETEC FLX 120 forms a flexible matrix of rubber polymer and hydrate structures, providing a tough breathable membrane that is impermeable to liquid water. BETEC FLX 120 is easily applied as slurry onto horizontal and vertical surfaces.

Product Uses

BETEC FLX 120 waterproof membrane is ideally suited for general purpose use on all commercial and residential  applications including:

  • Wet Areas – shower floors and walls, bathrooms, toilets, laundries, kitchens, equipment room floors.
  • Anti-Efflorescence Sealer – used over tile bed on decks and in wet areas to prevent calcium leachate staining.

Bonds securely to concrete, masonry, cement render, FC and CFC sheet, brick, block, ALC, etc.

Product Features

  • Complies with Green Star requirements - has very low VOC level
  • No toxic or hazardous ingredients
  • Water clean-up and low odour
  • Environmentally friendly
  • Simple application and fast cure
  • Resists continuous water immersion
  • Self-priming and non-staining
  • Total adhesion - no water tracking
  • Hardwearing - long life
  • Compatible with cement based tile adhesives
  • Crack bridging ability
  • Multi-purpose high build


Surfaces to be sound, smooth and free from dust, loose matter, oil, grease or other contaminants. All surface defects shall be repaired using CHEMBOND modified mortar.

Use SILCOR® LM PU sealant to fill joints, cracks and form fillets to all internal corners or penetrations and allow to fully cure a minimum 24 hrs before applying BETEC FLX 120.


  • Pour Part B (liquid) into a clean container. Stir with a low-speed, heavy-duty drill fitted with a paddle mixer.
  • Pour Part A (powder) slowly into Part B and mix to a uniform consistency.
  • Avoid lump formation during mixing and move paddle up and down in the mix. Check for any unmixed powder at the bottom of the container.
  • Use the clean plastic pails supplied as product packaging for mixing containers.

Typical Properties

Colour Part A – Dark Grey Powder
Mix Ratio
(by weight or volume)
Part A : Part B 1 : 1
Solids 90%
Application Temperature 5°C to 30°C
Pot Life 50 minutes @ 25°C
Through Cure 2 hours (1 mm @ 25°C)
Crack Bridging Up to 2 mm
Elongation 500%
Adhesion to Concrete (porous) 0.5 N/mm2

Bond Breaker

Use SILCOR LM PU sealant to form a 12mm angle in accordance with NCC as detailed by AS3740 and AS4654 for Class III waterproof membrane. Allow PU sealant to cure a min. 24 hours before proceeding with membrane installation.


  • Pre-dampen all porous substrates with clean water prior to application. Remove any ponded water.
  • Waterproof Membrane – Apply mixed slurry by broad soft brush, roller or broom in at least 2 layers, each in a cross direction to the other – min. 1.25mm Dry Film Thickness (DFT).
  • Anti-Efflorescence Sealer – Apply BETEC FLX 120 uniformly in one or two coats to achieve min. 1.0 mm DFT.
  • Allow to dry thoroughly between coats.
  • Always apply BETEC FLX 120 membrane on the side of the substrate that will be subject to hydrostatic pressure.


  • Seal high stress areas such as structural cracks, joints, penetrations and floor wastes, with Reinforcing Fabric PE embedded between two heavy layers of  NEWFLEX Grey . Allow this detail to fully cure before applying BETEC FLX 120 system.
  • Protect freshly applied BETEC FLX 120 membrane from site damage and exposure to heavy rain for 12 hours.
  • Avoid applying BETEC FLX 120 under conditions of strong sunlight. Do not apply BETEC FLX 120 to very hot, dry substrates – re-dampen with water if necessary.


BETEC FLX 120 membrane is foot trafficable for surfacing/tiling within 8 hours. Use the following systems for specific situations as listed. Apply surfacing materials only to fully cured BETEC FLX 120.

  • Tanking

Cover with PROTECTOBOARD™, PROTECTOBOARD™ HS or RAPID DRAIN™, followed by backfill or landscaping as required.

Rigid Surfaces

Use two layers of 0.2 mm PE slip-sheet with concrete topping. Paving slabs may be installed with a cement mortar bed or laid on sand. Ceramic tiles may be laid on bedding or directly fixed with polymer-modified cement-based adhesive. CHEMBOND™ polymer modified render or acrylic based textures may be applied directly to cured BETEC FLX 120.


BETEC FLX 120 40 kg set yields approx. 32 litres liquid membrane.

  • Internal Wet Areas

        Floors – minimum 2.0 litres/m2 (min. 1.25mm DFT)

        Walls – minimum 1.6 litres/m2 (min. 1.0mm DFT)

  • General (retaining walls, lift pits etc.)

        Minimum 2.25 litres/m2 (min. 1.5mm DFT)

  • Anti-Efflorescence Sealer

        Minimum 1.6 litres/m2 (min. 1.0mm DFT)      

  • Non-Potable Tanks

        Minimum 3.2 litres/m2 (min. 2.0mm DFT). Allow to dry thoroughly between coats.


BETEC FLX 120 is supplied in 40 kg kits.

Shelf Life

Unopened or resealed pails of BETEC FLX 120 have a shelf life of 12 months, when stored in a dry, cool place.


Remove uncured BETEC FLX 120 with water. MULTITEK Xylene may assist with the removal of cured product. Exercise care and review all SDS before solvent use.

Health and Safety

In case of spills and accidents, refer to the MSDS of the products or when in doubt contact your local GCP representative. Always wear protective clothing, gloves and protective goggles when handling chemical products. For full information, consult the relevant SDS.


Information contained in this document does not cover all possible application scenarios or imply product suitability for an application. Please contact your local GCP representative or the GCP Technical Department for further information.


GCP and contractors recognised by GCP as experienced in the application of GCP products will provide product warranties for individual projects. Product warranty periods offered are dependent on project details and complexity. Requests for long product warranty periods may necessitate increased membrane thicknesses to ensure longevity. GCP do not provide product warranties for membranes in negative pressure applications. Contact your local GCP representative for further details. | Australia customer service: 1800 855 525

We hope the information here will be helpful. It is based on data and knowledge considered to be true and accurate, and is offered for consideration, investigation and verification by the user, but we do not warrant the results to be obtained. Please read all statements, recommendations, and suggestions in conjunction with our conditions of sale, which apply to all goods supplied by us. No statement, recommendation, or suggestion is intended for any use that would infringe any patent, copyright, or other third party right.

Technologies, Inc. This trademark list has been compiled using available published information as of the publication date and may not accurately reflect current trademark ownership or status.

© Copyright 2021 GCP Applied Technologies, Inc. All rights reserved.

GCP Applied Technologies Inc., 2325 Lakeview Parkway, Alpharetta, GA 30009, USA
GCP Australia Pty. Ltd., 14 Colebard Street West, Archerfield, Brisbane, Queensland 4108, Australia
This document is only current as of the last updated date stated below and is valid only for use in Australia. It is important that you always refer to the currently available information at the URL below to provide the most current product information at the time of use. Additional literature such as Contractor Manuals, Technical Bulletins, Detail Drawings and detailing recommendations and other relevant documents are also available on Information found on other websites must not be relied upon, as they may not be up-to-date or applicable to the conditions in your location and we do not accept any responsibility for their content. If there are any conflicts or if you need more information, please contact GCP Customer Service.

Last Updated: 2023-07-06