PRESWELL HYDROPHILIC WATERSTOP Hydrophilic waterstop
Vulcanised hydrophilic polymer-rubber expansion strip, self-adhesive backed
Self-adhesive hydrophilic strip that swells to 400–500% of its volume to seal concrete construction joints.
PRESWELL HYDROPHILIC WATERSTOP sizes and key figures
Vulcanised polymer-rubber strip that seals construction and cold joints from within. It swells on water contact into a compression seal, and the self-adhesive backing needs no mechanical anchors.
- Swell
- 400–500%typicalof original volume on water contact · TDS p1
- After cycling
- ≥ 300%typicalexpansion kept after wet and dry cycles · TDS p2
- Roll
- 10 mstandard supply, 10 × 20 mm profile · TDS p2
- Profiles
- 7 sizes20 × 7 mm up to 20 × 30 mm, and 40 × 40 mm · TDS p2
- Hardness
- 45 ± 10typicalShore A, ISO 868 · TDS p2
- Tensile
- ≥ 3.0 MPatypicalISO 37 · TDS p2
- Elongation
- ≥ 350%typicalat break, ISO 37 · TDS p2
- Side lap
- Min 15 mmside-by-side, sealed with ACTFLEX PROSWELL · TDS p3
- Pour after
- From 8 hPROSWELL cure for hand-placed cover, 24 h for a large pour · TDS p3
From the FORSPEC data sheet, TDS-PRESWELL · Revision 2 · 28 October 2026. Times are at 25°C and 50% relative humidity unless the data sheet says otherwise. Typical = FORSPEC’s own typical value, not a laboratory-certified one.
Where PRESWELL HYDROPHILIC WATERSTOP is used
Use it for
- Construction joints in below-ground and water-retaining structures
- Wall-to-slab and slab-to-slab cold joints
- Raft slab and tank base joints
- Heavy-duty retaining walls
- Pipe and service penetrations through concrete
- Precast panel joints and lift pit construction joints
Know before you start
- Not a waterproofing membrane: it seals a joint, not an area
- Construction and cold joints only: not for expansion or movement joints
- Needs full concrete confinement and cover on both sides
- Keep dry before the pour: early swelling uses up its expansion
How to apply PRESWELL HYDROPHILIC WATERSTOP
- 01
Prepare
Joint face clean, sound and dry, free of laitance, dust, oil and release agents. Repair voids and grind back honeycombing. Confirm cover is achievable both sides.
- 02
Pick profile
Choose the profile from the table for the joint duty. Do not default to the smallest section that fits. Cut with a clean blade.
- 03
Fix
Smooth concrete: peel the liner, press on centred, then run an ACTFLEX PROSWELL bead along both edges. Rough concrete: bed the strip into a wet PROSWELL bead first.
- 04
Join
Lap lengths side by side with at least 15 mm in full contact and seal with PROSWELL. Never butt ends or stack strips. Carry it round corners without breaks.
- 05
Protect
Keep it dry from rain and site water until the pour. PROSWELL skin time is 65 minutes, then from 8 hours before hand-placed cover and from 24 hours before a large pour.
- 06
Pour
Confirm the strip is in place, adhered and dry. Place and compact concrete to fully encase it with no voids.
A short guide from the data sheet. Read the full PRESWELL HYDROPHILIC WATERSTOP TDS before you start.
Drawings for the systems it goes in
FORSPEC standard details as PDF and DXF. Each sheet is a generic detail: the specification names the products.
PRESWELL HYDROPHILIC WATERSTOP test reports and compliance
- ISO 868 hardness
- 45 ± 10 Shore A, manufacturer dataForspec R&D
- ISO 37 tensile and elongation
- ≥ 3.0 MPa and ≥ 350%, manufacturer dataForspec R&D
- Volume expansion
- ≥ 400%, accredited verification outstandingForspec R&D, internal test
- AS/NZS 4020 potable water
- No certificate held, no claim madeNot applicable
Results as stated in the data sheet, TDS-PRESWELL · Revision 2 · 28 October 2026. Warranty up to 25 years, depending on the system: ask FORSPEC which term applies to your system.
PRESWELL HYDROPHILIC WATERSTOP questions
How far does PRESWELL swell?
400–500% of its original volume on water contact. It keeps at least 300% expansion after repeated wet and dry cycles. These are typical R&D values, not certified.
Which profile do I need?
2007 (20 × 7 mm) light joints, 2010 (20 × 10 mm) standard wall and slab joints, 2015 (20 × 15 mm) more tolerance, 2020 high-movement cold joints, 2025 heavy-duty retaining walls, 2030 deep joints, 4040 (40 × 40 mm) large joints.
Do I need a sealant as well?
Yes. Allow ACTFLEX PROSWELL for every join, corner and penetration, and a bead along both edges of the strip on smooth concrete. On rough concrete it beds the strip along the full run.
What happens if it gets wet before the pour?
It starts swelling and uses up expansion capacity, so it will not re-seal at full performance. Protect it from rain, standing water and site water until concrete is placed.
Can it go in an expansion joint?
No. PRESWELL seals construction and cold joints only. Joint design, cover and hydrostatic duty are for the project engineer.
Is there anything I should know about handling it?
Yes. The SDS classifies PRESWELL as a hazardous chemical with the signal word DANGER. Read the SDS before use and wear gloves, eye and face protection.
Used with PRESWELL HYDROPHILIC WATERSTOP
PRESWELL HYDROPHILIC WATERSTOP TDS and SDS
Always work from the current data sheet. Every FORSPEC TDS and SDS →
Specify it. Or buy it.
Send the drawings or photos and FORSPEC comes back with the system, the details and the quantities. Or find a FORSPEC stockist for PRESWELL HYDROPHILIC WATERSTOP.