Split Flange - PVC Waterstop

About the Split Flange Profile

Split flange waterstops are specified when simplified forming is a priority. The flange is split lengthwise so it can be opened, laid over the bulkhead, and attached during placement of the first concrete element. After the bulkhead is stripped, the flange is closed and anchored for placement of the adjoining concrete. This approach eliminates the split formwork normally required for embedded waterstops, making split flange profiles particularly attractive when forming complexity or schedule pressure favors a simpler sequence. The hollow centerbulb sits over the joint and accommodates lateral, transverse, and shear movement, forming a continuous diaphragm intended to prevent the passage of liquid through the joint.

Split flange profiles have an important limitation: they are suitable for straight runs only. Transitions and intersections are not practical with these profiles, which means projects with frequent changes of direction or complex joint geometry will typically need a different waterstop family. Split flange waterstops are produced in widths of 6 inches and 9 inches across two weight classes and head pressure ratings, with the appropriate size depending on the project’s expected joint movement, hydrostatic head pressure, and concrete thickness.

Typical Applications

✓Commonly Specified For

Straight-run joints with no transitions or intersections
Projects where simplified forming is a priority
Expansion, contraction, and isolation joints in straight runs
Joints subject to lateral, transverse, or shear movement
Water and wastewater treatment plants
Reservoirs, tunnels, and containment structures
Potable water contact applications
Long runs of slab or wall joints without changes of direction

→Other Profiles May Be Considered When

The joint layout requires transitions, intersections, or changes of direction — see Ribbed Centerbulb
Better sealing characteristics are desired — see Ribbed Centerbulb
The joint has continuous reinforcement and minimal movement — see Flat Ribbed
The application is a slab-on-grade joint — see Base Seal
Larger joint movements are expected — see Tear Web profiles

Profile selection should always be verified against project specifications and engineering requirements. Contact us if you’d like assistance reviewing options for your application.

Available Sizes & Versions

Sika Greenstreak produces split flange waterstop in two profile sizes to suit different joint widths, movement requirements, and head pressure ratings.

Profile 724

Width: 6″

Thickness: 3/8″ / 3/16″ web

Weight: 1.54 lb/ft

Head Pressure: 125 ft (373 kPa)

Centerbulb: 3/8″ ID x 5/8″ OD

Profile 727

Width: 9″

Thickness: 3/8″ / 3/16″ web

Weight: 2.25 lb/ft

Head Pressure: 150 ft (448 kPa)

Centerbulb: 3/8″ ID x 5/8″ OD

Sizing considerations generally include expected joint movement, hydrostatic head, and concrete cover. Contact us if you’d like help cross-referencing a profile against your spec.

Installation Overview

Split flange waterstops install with a different sequence than other embedded profiles. The flange is split lengthwise so it can open up around the bulkhead — eliminating the need for the split formwork required by symmetrical embedded profiles. Heat welding is generally the recognized method for splicing PVC waterstop, though split flange profiles are limited to straight runs and don’t typically require field fabrications for changes of direction. Always refer to the manufacturer’s installation guide and project specifications for complete instructions.

Open & Attach

Open the split flange and attach it to the bulkhead for placement of the first concrete element.

Pour First

Place and consolidate the first concrete element, encapsulating one side of the waterstop.

Strip & Close

Strip the bulkhead, close the split flange, and anchor it in position for the adjoining pour.

Pour Second

Place the adjoining concrete element to encapsulate the second flange and complete the diaphragm.

Frequently Asked Questions

+What’s the advantage of a split flange waterstop?

The main advantage is simplified forming. With a standard embedded waterstop, contractors typically need split formwork — a bulkhead with a slot cut for the waterstop to pass through — so that half the profile is embedded in the first pour with the other half projecting through for the second. A split flange profile eliminates this. The flange opens up around the bulkhead and attaches to its face, then closes after the bulkhead is stripped. This can meaningfully simplify forming on long straight runs.

+Why are split flange profiles limited to straight runs?

The split flange geometry doesn’t lend itself to L’s, T’s, crosses, or other changes of direction. The opening and closing action that makes the forming simple on straight runs becomes impractical at corners and intersections, where the flange would need to bend in ways that compromise either the seal or the ability to close the flange properly. For projects with frequent changes of direction, a symmetrical embedded profile such as Ribbed Centerbulb is generally a better fit.

+What’s the difference between profile 724 and 727?

The 724 is 6″ wide and 1.54 lb/ft, rated for 125 ft of head pressure. The 727 is 9″ wide and 2.25 lb/ft, rated for 150 ft of head pressure. Both share the same 3/8″ ID x 5/8″ OD centerbulb and the same 3/8″ thickness with a 3/16″ web. The wider 727 provides greater concrete coverage on each flange and is rated for higher hydrostatic head. Project-specific requirements should always drive the final selection.

+Can split flange waterstop be installed in a horizontal slab joint?

Yes, split flange profiles can be installed in horizontal as well as vertical joints, provided the joint runs straight. The flange is opened and attached to the bulkhead of the first pour, then closed and anchored after the bulkhead is stripped. The benefit on horizontal slab joints is the ability to avoid cutting and threading the waterstop through split formwork.

+Is split flange waterstop suitable for potable water structures?

All Sika Greenstreak PVC waterstop profiles, including each split flange size, are NSF/ANSI 61 certified for potable water contact. This makes them appropriate for many applications such as finished water reservoirs and treatment plant clearwells, subject to project-specific requirements.

+How is split flange waterstop welded in the field?

PVC waterstop is typically heat-welded using a thermostatically controlled splicing iron. The two ends are squared, butted against the heated blade until the PVC begins to melt, then pressed together and held until cool. Because split flange profiles are limited to straight runs, field welding is usually only needed for straight butt splices between rolls. Sika offers a Waterstop Welding Certification Program for contractors seeking formal training, as weld quality has a significant impact on long-term performance.

Sika Split Flange