9.2 Waterstops: Materials, Installation & Splice Verification

Waterstops: Materials, Installation & Splice Verification

Waterstops limit fluid passage through concrete joints. The drawing and approved product data define the joint opening, expected movement, fluid exposure and installation. Basement wall joints, pits, reservoirs and containment structures can have different profiles and installation requirements. Follow the specified continuous waterstop path through straight runs, intersections and changes of plane.

For example, an approved centerbulb detail places the bulb at the joint plane so it can deform as the joint moves. The ribs or end anchors are held by the surrounding concrete. A hydrophilic strip works by swelling on contact with water inside the confined joint. Its permitted movement and required cover come from the product data. Compare the actual wall face and nearest edge to the required cover dimension and protect the strip from premature wetting. For GCP ADCOR 500S, the manufacturer requires at least 3 inches of surrounding concrete cover. A strip with 2-1/2 inches at the nearest face misses that requirement by 1/2 inch. Report the condition and obtain the disposition before it is concealed.

1. Verify position and support before the first placement

In a split-form detail with a cast-in PVC profile centered on the joint, the bulkhead holds the profile so one flange embeds in each placement. Confirm that the waterstop follows the joint line and that the form fits firmly around it without pinching or excessive paste leakage. Check the reinforcement clearance and access for consolidation, particularly under a horizontal flange. A tight space between the waterstop and steel can prevent aggregate and mortar from filling it.

Sika’s Greenstreak PVC installation guide, for example, gives field-applied hog rings at 12-inch centers between the outer ribs as one fastening method. It also identifies factory grommets or prepunched holes for applicable profiles. Tie the approved fastening points to adjacent reinforcement. Check that the fasteners are secure and that nails, screws and wires have not pierced the body or bulb. Use the selected product’s support spacing and fastening details.

As concrete is placed, observe whether the waterstop holds its shape and position. Look for rollover, especially where the concrete can load one side of an unsupported flange. Consolidate around and beneath the profile using the approved placement procedure. Keep the vibrator from striking the profile and watch for trapped air or a lack of mortar around the embedded portions.

2. Inspect continuity and field splices

For Sika Greenstreak PVC, use the manufacturer’s thermostatically controlled welding iron to make straight butt welds. The ends must align so the ribs and centerbulb match across the finished splice. For this product, the guide calls for square cuts and indirect heating at roughly 380°F with the controlled iron. Align the melted ends and hold them steady as the splice cools. Follow the approved fittings and transition details at corners, tees and crosses. A taped or glued overlap does not substitute for the specified butt weld.

Inspect the cooled splice for profile mismatch, cracks, charring, voids and separation. Verify any required testing against the approved specification and product procedures. For example, a centerbulb whose opening is interrupted by offset ends needs a documented disposition before installation. Record the location and condition of rejected or repaired splices and reinspect the corrected joint.

3. Check the exposed side before closing the second placement

After the bulkhead comes off, inspect the exposed flange for folded or torn areas, displaced fasteners, punctures and concrete residue that could interfere with the second placement. Verify the approved cleaning or repair method so the profile stays intact. For a hydrophilic strip, verify the surface preparation, attachment, end connections and required cover before placement, and check for premature swelling or damage. ADCOR 500S instructions, for example, call for a side-by-side overlap of at least 4 inches with full contact. They direct installers to replace prematurely swollen sections before concrete placement. Photograph and locate any discrepancy while it remains accessible. Then verify the corrected condition and record the second-placement observations.