Sika Sika Greenstreak Swellstop

Sika Greenstreak Swellstop is a high-performance, butyl polymer-based water-swellable sealant tape engineered to create a permanent watertight seal in non-moving concrete joints. On contact with water, Swellstop begins to swell — expanding over 25% by weight within 72 hours and up to 140–170% after extended water exposure — effectively filling gaps and voids to stop water infiltration at the joint. Designed specifically for below-grade waterproofing, Swellstop bonds directly to clean, dry concrete without special tools or heating equipment, making it one of the most straightforward concrete joint sealants to install on the market.

Unlike PVC or rubber waterstops that rely on mechanical embedment, Swellstop’s hydrophilic expansion mechanism actively seals the joint as water pressure increases. It remains flexible and workable in temperatures as low as -40°F, will not shrink or harden in cold conditions, and stays pliable in heat without becoming spongy — making it suitable for year-round installation across a wide range of climates and job site conditions.

Swellstop is ideal for foundation slabs, below-grade walls, precast concrete wall panel systems, septic tanks, sanitary and storm sewer manholes, utility vaults, potable water tanks, box culverts, wet wells, and pipe penetrations. It is important to note that Swellstop is not an expansion joint material and is intended exclusively for static, non-moving joint applications.

Available Sizes

Key Features

Swellstop’s defining characteristic is its hydrophilic expansion technology — a water-swellable butyl polymer formula that actively responds to moisture by swelling to fill and seal gaps in concrete joints. This makes it especially effective in below-grade environments where water pressure and joint integrity are ongoing concerns. The sealant is specifically engineered for non-moving, static joints, where its powerful adhesion to clean, dry concrete surfaces ensures a secure, lasting bond without the need for mechanical fasteners or embedded hardware.

One of Swellstop’s most practical advantages is its all-weather performance. The sealant remains flexible and fully functional across a wide temperature range, never shrinking or hardening in cold conditions and staying pliable without becoming spongy in heat. This thermal stability makes it a reliable choice for projects in virtually any climate, and since no special heating equipment or mixing is required, installation is straightforward for crews of any experience level.

Versatility is another hallmark of the Swellstop system. It performs equally well in foundation slabs, below-grade walls, precast concrete panel systems, septic tanks, sanitary and storm sewer manholes, utility vaults, potable water tanks, box culverts, and wet wells. Whether the application involves new poured-in-place construction or precast assembly, Swellstop delivers consistent waterproofing performance where dependable joint sealing is critical.

Technical Specifications

Frequently Asked Questions

What types of joints is Swellstop suitable for? Swellstop is designed exclusively for non-moving, static concrete joints, including cold joints in foundation slabs, below-grade walls, precast concrete panel systems, septic tanks, sanitary and storm sewer manholes, utility vaults, and wet wells. It is not appropriate for expansion joints or any application where significant joint movement is expected.

Does Swellstop require a primer? While Swellstop will adhere to clean, dry concrete on its own, the use of Swellstop Primer Adhesive is strongly recommended for best results — particularly on vertical joints where the risk of displacement during concrete placement is higher. The primer should be brush-applied in a 2-inch wide continuous coat and allowed to dry for two hours before the Swellstop is pressed into place.

How long does Swellstop take to swell? Swellstop begins expanding immediately upon contact with water. Within the first 72 hours of water immersion, it expands over 25% by weight. With extended exposure over approximately two months, it can expand between 140–170% by weight, progressively tightening the seal as conditions demand.

Is Swellstop suitable for expansion joints? No. Swellstop is engineered specifically for static, non-moving joints and should never be used as an expansion joint material. The expansion pressure generated by the swelling process can cause cracking or spalling in concrete if the joint is subject to movement or if insufficient concrete coverage is provided.

How much concrete coverage is required over Swellstop? A minimum of 2 inches of concrete coverage is recommended. For lightweight or lower-strength concrete with a compressive strength below 3,500 PSI, additional coverage beyond the 2-inch minimum should be considered to prevent cracking or spalling caused by the sealant’s expansion pressure.

Can Swellstop be used in potable water applications? Yes. Swellstop is suitable for use in potable water tanks and similar structures. It is clean to the touch, odorless, and does not contain any materials that can discolor concrete or irritate the skin, making it a safe and practical choice for water containment applications.

How is Swellstop spliced at corners and intersections? Swellstop should be spliced by butting the ends together with no gaps or air pockets — do not overlap the ends. Miter cuts at intersections are not required. The material’s pliable nature allows it to be bent around corners, eliminating the need for a 90-degree splice in many cases. To minimize the number of splices, install Swellstop in the longest practical lengths possible.

How should Swellstop be stored on the job site? Swellstop should be stored and protected from moisture, dirt, oil, and direct sunlight throughout the course of the work. The separation paper should remain on the waterstop until just before the second concrete pour. Prior to pouring, inspect the installed Swellstop for signs of premature swelling, damage, or debris contamination — if any swelling or damage is found, the affected section should be removed and replaced with new material.