For large external sheet-membrane installations on concrete, screed, brick, CFC sheet, timber, and some PVC substrates, WA 98 Contact Adhesive provides the extended tack window required to secure membranes over high-volume areas. This solvent-based neoprene contact adhesive is formulated specifically for bonding ARDEX Weldtec, ARDEX Butynol, and ARDEX WPM 116 membrane systems.
WA 98 Contact Adhesive is a polychloroprene contact adhesive designed for simultaneous application to both the prepared substrate and the underside of the sheet membrane. Once applied by brush, roller, or spray, the solvent evaporates to leave a tacky, high-bond film. Bringing the two coated surfaces together after the initial flash-off creates an immediate, high-strength contact bond. For porous masonry or concrete, a two-coat system is used, either by applying a neat primer coat of WA 98 Contact Adhesive and allowing it to dry completely before the adhesive bonding coat, or by thinning the first coat up to 50% with ARDEX WA 98 Solvent to penetrate deep into the pores before applying a neat second coat.
Use this contact adhesive for external sheet membrane installations on:
All surfaces must be mechanically prepared and vacuumed to remove dirt, dust, curing compounds, oils, grease, and surface sealers before application. Masonry and concrete substrates with high moisture levels require specific pre-treatment to prevent bond failure:
Stir or shake the unopened 20-litre drum thoroughly before use. Apply using one of the following methods:
No, ARDEX WA 98 Adhesive is strictly for external applications only. It is a highly flammable, solvent-based product requiring well-ventilated areas due to its chemical composition and hazard profile.
Concrete with moisture content above 80% RH or 15g/m²/24hrs requires priming with ARDEX WPM 300. For extremely porous concrete, dilute the first coat of ARDEX WA 98 Adhesive up to 50% with ARDEX WA 98 Solvent to aid penetration.
ARDEX WA 98 Adhesive has a working time of 15-60 minutes, becoming tacky in approximately 15-20 minutes. This extended tack time is designed for efficient membrane placement over large external areas.
Bubbling is typically caused by solvent entrapment if the membrane is embedded too early. Ensure the adhesive is tacky but not fully dry before bedding the sheet membrane.
| Application | Key benefit | Primary trades |
|---|---|---|
| Bonding ARDEX sheet applied membranes externally | Provides a high-performance, system-compatible bond for ARDEX Weldtec™, Butynol, and WPM 116. | Waterproofers, Builders |
| Large external area membrane installations | Extended tack time (15-60 minutes) allows for accurate membrane positioning and efficient work sequencing without premature curing. | Commercial Waterproofers, Roofing Contractors |
| Bonding to concrete/masonry with elevated moisture | Maintains adhesion when used with ARDEX WPM 300 primer on substrates exceeding 80% RH or 15g/m²/24hrs, ensuring system integrity. | Remedial Waterproofers, Builders |
| Application onto extremely porous substrates | Can be thinned with ARDEX WA 98 Solvent to ensure deep penetration and a strong mechanical key. | Waterproofers, Builders |
| Efficient, large-scale adhesive application | Brush, roller, or spray application options, with thinning capability for spray, enhance productivity on large projects. | Commercial Waterproofers |
Ensure the substrate is clean, dry, and structurally sound. Remove all dust, oils, grease, curing compounds and other contaminants. For damp concrete, a moisture barrier system like Ardex WPM 300 must be used.
Thoroughly shake and stir the drum before use. Apply a thin, consistent coat of Ardex WA 98 to both the prepared substrate and the underside of the Ardex sheet membrane.
Apply evenly, ensuring no pooling or thick spots. Aim for a coverage rate of 4-8m² per litre.
For optimal flow, thin adhesive with Ardex WA 98 Solvent. Trial the mix ratio to suit your equipment before full application.
Allow the adhesive on both surfaces to air dry until it is tacky to a light touch. Carefully position the membrane and apply firm, uniform pressure with a roller to ensure full contact and eliminate any air pockets.
Danger: Highly flammable liquid and vapour. Harmful if swallowed. May be fatal if swallowed and enters airways. Causes skin and serious eye irritation. May cause drowsiness or dizziness. Suspected of damaging fertility and the unborn child. May cause damage to organs through prolonged or repeated exposure.
Wear chemical protective gloves (e.g., PVC or Nitrile for short-term use, ensure correct selection based on breakthrough time), safety glasses with side shields or chemical goggles, and safety footwear. For severe exposure, PVC protective suit and appropriate respiratory protection (Type AX Filter) are required. Use an eyewash unit.
Ensure adequate mechanical ventilation during application. Use only outdoors or in a well-ventilated area to prevent vapour build-up and irritating atmospheres. Do not breathe mist/vapours/spray.
Store in original sealed containers in a dry place at 23˚C and 50% relative humidity, away from direct sunlight, ignition sources, and open flame. Keep containers securely sealed and store locked up. Dispose of contents and container at an authorised hazardous waste collection point in accordance with local regulations.
Proper substrate preparation is critical for adhesion and system performance with ARDEX WA 98 Adhesive, preventing common failures like delamination.
Surface prep: Remove all dirt, dust, curing compounds, oils, grease, surface sealers, and contaminants mechanically and via vacuum cleaning. Surface must be sound and free from laitance.
Primer: Optional, but required for damp substrates. If moisture content is greater than 80% RH (ASTM F2170) or exceeds 15g/m²/24hrs (ASTM F1869), apply two coats of ARDEX WPM 300 (HydrEpoxy) at 3m²/litre per coat, allowing 24 hours to dry. Then, apply a neat primer coat of ARDEX WA 98 Adhesive and allow to dry before the final application.
Surface prep: Ensure surfaces are clean, dry, sound, and free from loose material, dust, and other bond-inhibiting contaminants. Abrade smooth or glossy surfaces for optimal key.
Primer: Not required for dry, prepared surfaces. For extremely porous substrates, a first coat diluted up to 50% with ARDEX WA 98 Solvent will enhance penetration and adhesion, followed by a neat second coat.
Surface prep: Clean thoroughly to remove all plasticisers, oils, and contaminants. Roughen the surface with abrasive paper to provide a mechanical key.
Primer: Not required. Always conduct a small test patch to confirm compatibility and adhesion before full application, as PVC types can vary.
| Property | Value |
|---|---|
| Composition | Polychloroprene (Neoprene®) |
| Viscosity | 130 ± 20 cP |
| Application Temperature | 10ºC - 35ºC (substrate and/or ambient) |
| Service Temperature | -20ºC - 92ºC |
| Pot Life | 15 - 60 minutes (temperature dependent) |
| Peel Strength (ASTM D903) Membrane to Plywood - Butyl | 30 - 35 N |
| Peel Strength (ASTM D903) Membrane to Plywood - EPDM | 7 - 10 N |
| Coverage | 4m² - 8m²/litre (approximately) |
| Form | Liquid |
| Specific Gravity | 0.825-0.835 |
| Boiling Point | 54 °C (IBP) |
| Flash Point | -15 °C |
| Upper Explosive Limit | 7 % |
| Lower Explosive Limit | 1 % |
| Vapour Pressure @ 20C | 24.1 kPa |
| Solubility in Water | Immiscible |
| Peel Strength | 30 - 35N (Butyl); 7 - 10N (EPDM) |
Here are some common examples on where Ardex WA 98 Contact Adhesive used by our customers.
