Everything engineers, specifiers, and contractors need to know — from joint type selection to product specifications, installation requirements, and compliance standards.
What is a retrofit waterstop?
A retrofit waterstop is a waterproofing system designed specifically for joints where new concrete is poured against an existing concrete structure. Unlike traditional embedded waterstops — which are cast into both sides of a joint during original construction — retrofit systems are anchored mechanically to the face of the existing structure before the new concrete is placed.
The result is a continuous, watertight diaphragm across the joint that prevents fluid migration even under sustained hydrostatic pressure. Retrofit waterstops bridge the gap between old and new, making them the correct specification whenever one side of a joint is already hardened concrete and reconstruction is not an option.
Cast into fresh concrete on both sides of a new joint during original construction. Requires split formwork and two sequential pours. Not viable when one side is already hardened.
Anchored to the face of existing concrete using stainless steel batten bars, anchor bolts, and structural epoxy gel. New concrete is then poured against the installed profile.
When do you need a retrofit waterstop?
Retrofit waterstops are specified whenever a new concrete element must be joined to an existing structure and the joint must remain permanently watertight. They are the standard solution for infrastructure repair, facility expansion, and structural rehabilitation projects where demolishing the existing concrete is not practical or cost-effective.
Common applications include water and wastewater treatment plant upgrades, containment wall repairs, below-grade concrete restoration, dam and lock structure rehabilitation, and tunnel lining additions. Any project where one side of the joint is already cured concrete is a candidate.
Tank and basin expansion
Tunnel rehabilitation
Containment wall repair
Below-grade concrete restoration
Wastewater facility renovation
Dam and lock structure repair
Retaining wall addition
Reservoir and aqueduct work
Foundation wall expansion
How retrofit waterstop systems work
All Sika Greenstreak PVC retrofit systems use the same core mechanism: a flexible PVC profile is anchored flat against the face of the existing concrete, then encapsulated by the new concrete pour. The three components — mechanical anchoring, structural epoxy bonding, and PVC embedment — work together to form a seamless waterproofing diaphragm across the joint.
Mechanical anchoring: Stainless steel batten bars and anchor bolts fasten the PVC profile directly to the face of the existing concrete at regular intervals, holding it firmly in position during the new pour.
Epoxy bonding: Sika 7300 structural epoxy gel is applied between the PVC flange and the concrete surface, filling surface voids and creating a watertight bond at the anchorage interface to eliminate bypass pathways.
Concrete encapsulation: New concrete is poured and consolidated against the installed profile. The embedded portion of the PVC is fully encapsulated, forming a continuous waterproof diaphragm spanning the full joint depth.
Why flexible PVC? PVC is the industry standard for waterstop material because of its inherent elasticity, chemical resistance, and ability to accommodate joint movement. It will not discolor concrete, produce electrolytic action, or degrade under long-term water contact.
Choosing the right retrofit profile
Profile selection comes down to three primary variables: the width of the profile (which determines embedment depth and hydrostatic resistance), the expected head pressure at the joint, and whether the structure requires NSF-61 certification for potable water contact. All four Sika Greenstreak retrofit profiles use the same stainless steel anchoring system and are suitable for both vertical and horizontal joint applications.
Profiles 581 and 655. Best where wall thickness or access is limited and head pressure is moderate. Suitable for tanks, vaults, and general containment.
Profile 609. Most versatile option. Compatible with both vertical and horizontal joint transitions.
Profile 667. For hydrostatic head up to 150 ft (448 kPa). Dams, deep tunnels, and critical high-pressure containment structures.
For joints in potable water structures, all four profiles carry NSF-61 certification for potable water suitability. If the project involves significant joint movement — from thermal cycling, settlement, or live load deflection — confirm anchoring spacing and profile selection with Sika prior to specifying.
Product lineup: Sika Greenstreak retrofit systems
Four profiles cover the full range of retrofit waterproofing applications — from compact repairs in tight spaces to heavy-duty sealing under extreme hydrostatic pressure. All profiles are sold as 10-foot pieces and include stainless steel batten bar hardware. Structural epoxy is sold separately for the 581, 655, and 667; the 609 system includes epoxy.
3 11/16″ wide · 1.51 lb/ft with hardware · Ideal for tanks, vaults, and space-constrained joints
NSF-61 certified
6″ wide · 2.92 lb/ft · Vertical & horizontal joints · Epoxy included
NSF-61 certified
3″ wide · Meets ASTM & Corps of Engineers specs · Tanks, tunnels, retaining walls
NSF-61 certified
9″ wide · 8.27 lb/ft · Rated to 150 ft head (448 kPa) · High-pressure applications
NSF-61 certified
Factory fabrications: Waterstop failures occur most often at improperly field-welded transitions and intersections. Factory-made fabrications are strongly recommended for all profile changes, corners, and intersection points.
Physical properties — all PVC profiles
All Sika Greenstreak PVC waterstops are specially formulated and manufactured to meet or exceed the following industry-standard physical property requirements. These values apply across the full retrofit product line.
Installation overview
Retrofit waterstop installation is a precise process that requires careful surface preparation, correct epoxy application, and proper mechanical anchoring before new concrete is placed. Skipping or rushing any of these steps is the primary cause of long-term joint failures. The sequence below applies to all four Sika Greenstreak retrofit profiles.
Prepare the existing surface. Clean and profile the concrete face. Remove laitance, oil, dirt, and any loose or unsound material. A clean, sound surface is critical for epoxy adhesion.
Position the waterstop profile. Place the PVC profile flat against the existing concrete face, centered on the joint line. The centerline of the profile must align with the center of the joint.
Apply structural epoxy gel. Apply Sika 7300 gel between the PVC flange and the concrete surface to ensure a void-free, watertight bond at the anchorage interface.
Install stainless steel anchoring hardware. Fasten the batten bars and anchor bolts at the specified spacing to mechanically secure the profile to the existing concrete.
Heat weld transitions and intersections. Use a Sika Greenstreak splicing iron to join profile lengths, corners, and intersections. Factory-fabricated fittings are strongly preferred over field welding at all transitions.
Place and consolidate new concrete. Pour new concrete against the installed profile. Consolidate carefully to ensure full encapsulation of the embedded portion with no voids.
Heat welding is the only recognized installation method for splicing PVC waterstop. Sika’s Waterstop Welding Certification Program is available for contractors and employees to fulfill training requirements. Full installation guides, splicing instructions, and application guides are available through Sika’s technical documentation library at usa.sika.com.
Compliance & certifications
Sika Greenstreak PVC waterstops are manufactured to meet or exceed the industry’s most demanding performance specifications. All PVC and TPER waterstop profiles in the Greenstreak line are NSF-61 certified, making them suitable for potable water contact applications where required by the project specification.
Army Corps of Engineers CRD-C 572-74
ASTM D638 — tensile & elongation
ASTM D624 — tear resistance
ASTM D746 — low temp. brittleness
ASTM D2240 — Shore A hardness
ASTM D570 — water absorption
ASTM D747 — stiffness in flexure
ASTM D792 — specific gravity
The 655 and 667 profiles are manufactured from prime virgin PVC and meet Corps of Engineers and ASTM performance specifications. Confirm current certification status and project-specific compliance requirements directly with Sika prior to final specification.
Waterstop design checklist
Use this checklist when specifying a retrofit waterstop system. Working through these items before writing the specification will reduce RFIs, minimize substitution requests, and ensure the installed system performs as intended for the life of the structure.
Frequently asked questions
Common questions from engineers, specifiers, and contractors about PVC retrofit waterstop systems.
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