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- 2 Crack Repair (if required)
- 3 ACTFLEX FLEXPLUS
- 4 ACTFLEX HYDROPLUG
- 5 ACTFLEX AT MESH
- 6 ACTFLEX 988 CWP (2 Coats)
- 7 Tile Adhesive
- 8 Pool Finish
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Hydrophilic waterstop for concrete construction joints. 20 x 10 mm profile, 10 m roll, self-adhesive backed.
PRESWELL is a vulcanised polymer-rubber hydrophilic strip that seals concrete construction joints from within. On contact with water it expands to 400–500% of its original volume, forming a compression seal against the surrounding concrete. Use it with ACTFLEX PROSWELL: bed the strip on PROSWELL on rough concrete, and seal every join with it.
What it's for
Why waterproofers buy it
Not for
Keep the strip dry until the pour.
Pickup currently unavailable at The Waterproofing Shop

PRESWELL Hydrophilic Waterstop
The Waterproofing Shop
22/872 Canterbury Road
Roselands NSW 2196
Australia

Correct application makes all the difference.
Not a waterproofing membrane. PRESWELL seals a joint within a structure; it does not waterproof an area. It requires full concrete confinement on all sides to develop the compression seal and must not be installed where it can swell freely into a void. Minimum concrete cover must be maintained on both sides of the strip; insufficient cover allows the swelling pressure to spall the concrete edge. Not for use in expansion or movement joints - PRESWELL seals construction and cold joints only. Must not be exposed to water, rain or standing water before the concrete is poured; premature swelling consumes the expansion capacity and the strip will not re-seal at full performance. Do not stretch the strip during installation. Do not install over dust, laitance, standing water, oil, grease, curing compounds or release agents. Joint design, concrete cover and hydrostatic duty must be determined by the project engineer. Classified a HAZARDOUS CHEMICAL, signal word DANGER, with hazard statements including H317, H318, H334, H350 may cause cancer and H411; wear protective gloves, protective clothing, eye protection and face protection and do not handle until all safety precautions have been read and understood.
| Product Type | Vulcanised hydrophilic polymer-rubber expansion strip |
| Chemical Base | Natural rubber with hydrophilic polymer additives - sodium polyacrylate, plasticisers, viscosifiers and anti-ageing agents |
| Hardness | 45 +/- 10 Shore A (ISO 868)* |
| Tensile Strength | Minimum 3.0 MPa (ISO 37)* |
| Elongation at Break | Minimum 350% (ISO 37)* |
| Volume Expansion | Minimum 400%, 1 to 5 times original volume (internal test)* |
| Tensile Strength After Repeated Immersion | Minimum 2.0 MPa (ISO 37)* |
| Elongation After Repeated Immersion | Minimum 250% (ISO 37)* |
| Expansion After Cycling | Minimum 300% (internal test)* |
| Low Temperature Flexibility | No cracking at -20C for 2 hours (internal test)* |
| Chemical Resistance | Resistant to groundwater salts* |
| Hydrostatic Resistance | Suitable for high pressure when correctly installed* |
| Colours | Red, blue or black |
| Backing | Factory-applied self-adhesive |
| Standard Supply | 10 m roll, 10 mm x 20 mm profile standard |
| Profile Range | 2007 (20 x 7 mm), 2010 (20 x 10 mm), 2015 (20 x 15 mm), 2020 (20 x 20 mm), 2025 (20 x 25 mm), 2030 (20 x 30 mm), 4040 (40 x 40 mm) |
| Adhesion of Self-Adhesive Backing | Immediate on pressing, no cure period* |
| Shelf Life | 24 months, unopened, stored dry and shaded* |
| Hazard Classification | HAZARDOUS CHEMICAL and NON-DANGEROUS GOODS under the WHS Regulations and the ADG Code, signal word DANGER, Chemwatch 9010-10 |
| * Typical Forspec R&D characteristic values - no accredited certificate is held for this product | |
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Sydney, NSW
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Brisbane, QLD
Step-by-step from prep to top coat. Filmed on the tools, not in a studio.

We supply premium waterproofing products backed by expert advice, fast service and real-world experience.
PRESWELL is a hydrophilic swelling strip that prevents water ingress through concrete construction joints. The strip activates on water contact - it swells to create a compression seal against the surrounding concrete, sealing any micro-gaps.
PRESWELL expands 400-500% on water exposure - the swelling creates compression against the concrete that fills any micro-cracks or honeycomb at the joint. Self-healing for the life of the structure.
Bond the strip to clean concrete at the cold joint using the self-adhesive backing (mechanical fixing is optional for vertical or overhead applications). Pour the next lift of concrete directly over the strip - the swelling is delayed until water exposure.
10mm x 20mm profile in 10m roll length. Other thicknesses available: 7, 10, 15, 20, 25, 30, 40mm. Match the profile size to the joint width and expected water pressure.
PRESWELL pairs with PREBAR PVC waterstops and Forspec cementitious or crystalline waterproofing systems for belt-and-braces joint sealing. Specify PRESWELL where active water flow is expected at the joint.