What is PREBAR External (Rear Guard) used for?

PREBAR External is the rear-fixed variant of the PREBAR PVC Waterstop - fixed against formwork on the outer face of the joint rather than centrally embedded. Used where post-applied waterstop placement is preferred over central embedment.

Nail or fix the external waterstop to the formwork prior to concrete pour. The ribbed wing sits against the external face of the joint. Heat-weld splices for continuous runs. Strip the formwork after the concrete cures.

Same material as internal PREBAR?

Yes. Same PVC material as Internal PREBAR: Shore A 75 hardness, 330% elongation, service temperature -20°C to +50°C. The difference is the profile shape - external has flanges for surface fixing, internal has a centred barrier shape.

When use external vs internal?

Use external when access for centring an internal waterstop is impractical (one-side formwork, retrofit applications), or when belt-and-braces detailing requires both internal and external waterstops at the same joint.

Pairs with which Forspec products?

External PREBAR works with PRESWELL hydrophilic strips and Forspec liquid-applied membranes for full structural joint waterproofing systems. Reference the Forspec design library for compliant assemblies.

PREBAR PVC Waterstop Rear Guard (External) for external concrete construction joints, providing reliable watertight sealing and waterproof detailing.

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PREBAR PVC Waterstop External (Rear Guard)

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PVC waterstop for internal concrete joints. Flexible design prevents water seepage.

Prebar PVC Waterstop Internal is a flexible PVC strip cast into concrete construction joints. It blocks water under hydrostatic pressure at internal horizontal and vertical joints.

What it's for

Concrete construction joints in foundations, basements and retaining walls
Internal horizontal and vertical joints subject to water pressure
Combined with sealant in the sealing groove for full waterproofing

Why waterproofers buy it

Prevents water seepage through construction joints
Flexible to accommodate concrete movement
Embedded in concrete during pour for permanent installation
Long term durability. Does not absorb water

Not for

Expansion joints without sealant, dynamic joints (use flexible sealant), or above-water applications without additional protection.

Tensile strength of 15.49 MPa against a 12.00 MPa minimum requirement to BS 2782.320A

Heat weldable at 190C to 200C for continuous, leak-proof on-site joints

Prefabricated intersection pieces eliminate the site-fabricated tees and crosses where waterstops typically fail

Size: 150mm X 15m

150mm X 15m$242.00250MM X 12.5M$341.00

Quantity: 1

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PREBAR PVC Waterstop External (Rear Guard)

150mm X 15m

The Waterproofing Shop

Pickup available, usually ready in 24 hours

22/872 Canterbury Road
Roselands NSW 2196
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Product Details

FORSPEC PREBAR PVC WATERSTOP is a high-performance thermoplastic PVC profile designed for watertight sealing in cast-in-situ concrete joints.

Forspec It is compliant with BS 2782 standards, ensuring reliable performance in preventing water ingress through concrete joints.

Key Features & Benefits

Superior Waterproofing: Effectively prevents water ingress through concrete joints.

High Flexibility & Strength: Accommodates joint movement without compromising performance.

Chemical & Corrosion Resistance: Suitable for aggressive environments, including wastewater and industrial applications.

Easy Installation: Designed for simple integration into concrete formwork.

Compliance with Industry Standards: Manufactured to meet waterproofing regulations for concrete structures.

How to Use

Position the profile centred and correctly aligned in the joint, then heat weld all sections at approximately 190C to 200C to form continuous, leak-proof joints.Confirm the surfaces where the waterstop will be installed are clean, dry and free from debris and contaminants.
Confirm the formwork is set out to receive the waterstop centrally within the joint, with the design concrete cover achievable on both sides.
Confirm the correct profile, internal or external and construction or expansion joint, has been selected against the project design.
Confirm prefabricated intersection pieces are on site for every tee, cross and corner.
Confirm the reinforcement layout allows full concrete encasement and compaction around the profile.
Cut the waterstop to the required lengths with a clean blade, allowing adequate overlap at joints and intersections.
Position the waterstop within the construction joint, ensuring it is centred and correctly aligned.
For vertical joints, secure it with appropriate anchors or fixing methods.
Heat weld all sections at approximately 190C to 200C to form continuous, leak-proof joints, fully welded through the full section.
Install prefabricated intersection pieces at every tee, cross and corner to minimise site fabrication.
Inspect every weld for full fusion, alignment and freedom from voids before the pour.
Confirm the waterstop is secured, centred and undamaged immediately before concrete is placed.
Place and compact the concrete carefully around the profile to achieve full encasement with no voids.
Protect the exposed half of the waterstop from damage, contamination and concrete splatter until the second pour.
Clean the exposed half thoroughly before the second pour so that the concrete bonds to a clean profile.

Technical Specifications

Product Type: Thermoplastic polyvinyl chloride waterstop profile
Material: Polyvinyl chloride (PVC)
Colour: Blue
Tensile Strength: 15.49 MPa (BS 2782.320A, minimum requirement 12.00 MPa)
Elongation at Break: 330% (BS 2782.320A, minimum requirement 3.00%)
Hardness: 75 Shore A (BS 2782:365B)
Specific Gravity: 1.41 g/cm3 (BS 2782:620B)
Water Absorption at 23C: 0.19% (ISO 62)
Thermal Stability, Congo Red at 180C: Minimum 50 minutes (BS 2782:130A)
Welding Temperature: Approximately 190C to 200C *
Service Temperature Range: -25C to +70C *
Profiles: Internal and external, for construction and expansion joints *
Roll Weight: Dependent on profile type *
Storage Temperature: +10C to +40C *
Shelf Life: 5 years from the date of production, correctly stored *
* Typical Forspec R&D characteristic values, not for engineering design without written FORSPEC confirmation

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PREBAR PVC Waterstop External (Rear Guard)150mm X 15m

$242.00

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System Build-Up Guide

Correct application makes all the difference.

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Pool System Build-Up

1 Concrete Substrate
2 Crack Repair (if required)
3 ACTFLEX FLEXPLUS
4 ACTFLEX HYDROPLUG
5 ACTFLEX AT MESH
6 ACTFLEX 988 CWP (2 Coats)
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8 Backfill

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1 Concrete Substrate
2 Crack Repair (if required)
3 ACTFLEX FLEXPLUS
4 ACTFLEX AT MESH
5 ACTFLEX 988 WMP (2 Coats)
6 Protective Coating (Optional)
7 Water

Technical overview

PREBAR PVC WATERSTOP is a thermoplastic polyvinyl chloride profile cast into concrete joints to form a continuous watertight barrier through the structure. This listing is the external profile, used with the outer face of the joint. It is manufactured and tested to BS 2782 and develops 15.49 MPa tensile strength against a 12.00 MPa minimum and 330% elongation at break against a 3.00% minimum. It is heat weldable at 190C to 200C and is supplied with prefabricated intersection pieces for tees, crosses and corners. Forspec holds no accredited third-party certificate for this product. Batch certificates of analysis are conducted on the raw material used in production, and independent laboratory test results are available on request.

Key applications

Water-retaining structures - basement slabs, lift pits, retaining walls and suspended slabs
Swimming pools, reservoirs, water towers and sewage tanks
Dams, culverts, canals and spillways
Bunded areas around liquid-retaining tanks
Water-excluding structures - basements and underground car parks
Tunnels and subways
Abutments and retaining walls
Roof decks and podium areas
Construction and expansion joints in horizontal and vertical cast-in-situ concrete

Surface suitability

Concrete (cast-in-situ construction and expansion joints
waterstop centred in the joint and fully encased in concrete on both sides with the design cover maintained)

Not a waterproofing membrane. PREBAR PVC WATERSTOP seals a joint within the structure, it does not waterproof a surface. It must be fully encased in concrete on both sides with the design cover maintained, and centred and correctly aligned in the joint, because an off-centre waterstop halves the water path on one side. Do not install over dirty, wet or contaminated surfaces. Do not fold, kink or crease the profile, a folded waterstop creates a permanent water path. All joins must be fully heat welded; taped, glued or overlapped joins are not acceptable. Do not overheat during welding, PVC degrades above the stated welding range of approximately 190C to 200C. The waterstop must remain in position throughout the pour; secure vertical installations with appropriate anchors or fixings. Do not store above 40C or in direct sunlight. Joint design, profile selection and hydrostatic duty are the design responsibility of the project engineer.

Technical Specifications

Product Type	Thermoplastic polyvinyl chloride waterstop profile
Material	Polyvinyl chloride (PVC)
Colour	Blue
Tensile Strength	15.49 MPa (BS 2782.320A, minimum requirement 12.00 MPa)
Elongation at Break	330% (BS 2782.320A, minimum requirement 3.00%)
Hardness	75 Shore A (BS 2782:365B)
Specific Gravity	1.41 g/cm3 (BS 2782:620B)
Water Absorption at 23C	0.19% (ISO 62)
Thermal Stability, Congo Red at 180C	Minimum 50 minutes (BS 2782:130A)
Welding Temperature	Approximately 190C to 200C *
Service Temperature Range	-25C to +70C *
Profiles	Internal and external, for construction and expansion joints *
Roll Weight	Dependent on profile type *
Storage Temperature	+10C to +40C *
Shelf Life	5 years from the date of production, correctly stored *
* Typical Forspec R&D characteristic values, not for engineering design without written FORSPEC confirmation

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Frequently asked questions

View all FAQs

What is PREBAR External (Rear Guard) used for?

Compatibility
PREBAR External is the rear-fixed variant of the PREBAR PVC Waterstop - fixed against formwork on the outer face of the joint rather than centrally embedded. Used where post-applied waterstop placement is preferred over central embedment.
How is it installed?

Installation
Nail or fix the external waterstop to the formwork prior to concrete pour. The ribbed wing sits against the external face of the joint. Heat-weld splices for continuous runs. Strip the formwork after the concrete cures.
Same material as internal PREBAR?

Performance
Yes. Same PVC material as Internal PREBAR: Shore A 75 hardness, 330% elongation, service temperature -20°C to +50°C. The difference is the profile shape - external has flanges for surface fixing, internal has a centred barrier shape.
When use external vs internal?

Compatibility
Use external when access for centring an internal waterstop is impractical (one-side formwork, retrofit applications), or when belt-and-braces detailing requires both internal and external waterstops at the same joint.
Pairs with which Forspec products?

Compliance
External PREBAR works with PRESWELL hydrophilic strips and Forspec liquid-applied membranes for full structural joint waterproofing systems. Reference the Forspec design library for compliant assemblies.

PREBAR PVC Waterstop External (Rear Guard)

Frequently bought together

Pool System Build-Up

Retaining Wall System Build-Up

Tank System Build-Up

Technical overview

Key applications

Surface suitability

Technical Specifications

Pool Renovation

Below Ground Retaining Wall

Concrete Water Tank

Commercial Podium

Swimming Pool Construction

The Waterproofing Shop?

Frequently asked questions

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