Material selection, chemical compatibility, and installation guidance for TPE-R, polyethylene, and stainless steel waterstop systems in industrial and secondary containment applications.
What is a chemical resistant waterstop?
A chemical resistant waterstop is a joint sealing element embedded in concrete that prevents the migration of aggressive chemicals — including hydrocarbons, acids, bases, fuels, and solvents — through construction and expansion joints. Unlike standard flexible PVC waterstops, which can degrade or fail when exposed to harsh industrial chemicals, chemical resistant waterstops are manufactured from materials specifically engineered to maintain their physical properties and watertight performance under aggressive chemical exposure.
Sika’s Westec product line is the industry standard for chemical resistant waterstop, offering three distinct material options: Westec TPE-R (Thermoplastic Elastomeric Rubber), Westec PE (Polyethylene), and Westec SS (316 Stainless Steel). Each material is engineered for a specific range of chemical and thermal conditions, allowing engineers to specify the optimal solution for their containment requirements.
Suitable for water and mild aqueous environments. Will degrade or fail in contact with many hydrocarbons, fuels, and strong solvents.
Engineered for industrial environments with aggressive chemical exposure, secondary containment, fuel and petrochemical contact, and high-temperature service.
When do you need a chemical resistant waterstop?
Chemical resistant waterstops are specified anywhere a concrete joint may come into contact with industrial chemicals, fuels, solvents, or high-temperature liquids over the service life of the structure. They are essential for secondary containment systems at refineries, petrochemical plants, pharmaceutical facilities, biofuel production sites, and any installation where leakage through a joint could result in environmental contamination or regulatory non-compliance.
If your project involves any of the following industrial applications, a chemical resistant waterstop should be specified in place of standard PVC:
Petrochemical manufacturing
Oil refineries
Pulp and paper mills
Land, air and seaports
Fuel storage & tank farms
Pipeline secondary containment
Pharmaceutical plants
Ozone contact structures
High-temperature service (>250°F)
How chemical resistant waterstop systems work
All Westec chemical resistant waterstops operate on the same fundamental principle as traditional PVC waterstops: when embedded in concrete across or along the joint, they form a continuous watertight diaphragm that physically blocks the passage of liquid through the joint. The difference is the material — each Westec waterstop is manufactured from a polymer or alloy specifically chosen for its chemical and thermal resistance characteristics.
Embedded placement: For standard embedded profiles, the waterstop is positioned in the joint prior to concrete placement, with the centerline of the profile aligned to the center of the joint. Half of the profile is encapsulated in the first concrete pour; the other half projects into the second pour. Retrofit profiles install differently — anchored mechanically to the face of an existing structure before a single new pour (see the callout below).
Mechanical anchoring through ribs: The ribbed profile geometry mechanically locks the waterstop into the surrounding concrete, while centerbulb or tear web features accommodate joint movement without breaking the seal.
Chemical barrier formation: The continuous waterstop diaphragm spans the full joint depth, physically blocking the migration of stored or spilled chemicals through the joint to the soil, groundwater, or adjacent compartments.
Retrofit applications: All Westec retrofit systems include stainless steel batten bars and tapcons. Westec 151 Novolac Gel Epoxy creates a fluid-tight and chemical-resistant seal between the waterstop and the existing concrete face.
Choosing the right material — TPE-R, PE, or stainless steel
Material selection is the single most important decision in specifying a chemical resistant waterstop. Each of the three Westec materials has a distinct chemical compatibility profile, mechanical property set, and service environment. Selection should be driven by the specific chemicals to be contained, the service temperature, joint movement requirements, and whether NSF-61 certification is required.
The versatile default. Flexible, rubber-like sealing with broad chemical resistance and NSF-61 certified versions (Envirostop). Best for most secondary containment and ozone contact applications.
Specialized for hydrocarbon exposure. Particularly effective for benzene, toluene, and xylene contact. More plastic-like and rigid than TPE-R, with higher chemical resistance in specific applications.
The premium option for the most severe conditions. Specified for high temperatures above 250°F and the most aggressive chemical environments where polymer materials are not viable.
In recent years, many applications that traditionally specified stainless steel waterstop have been successfully converted to Westec TPE-R, particularly for ozone contact structures and certain chemical applications. TPE-R offers significant cost savings and easier installation while still meeting the performance requirements of many demanding applications. Consult Sika’s chemical resistance data and your project chemist before final selection.
Material lineup: Westec chemical resistant waterstops
Each of the three Westec materials is offered in a range of profile geometries — including ribbed centerbulb, ribbed tear web, retrofit, EB Cap, and base seal — so engineers can pair the right material with the right profile for any joint type or movement requirement.
Fully vulcanized blend of EPDM and polypropylene (TPV). Combines rubber-like flexibility with heat-weldable thermoplastic processing. Excellent resistance to oils, fuels, acids, bases, and solvents.
NSF-61 certified (Envirostop)
Very low density polyethylene with increased elastic modulus and hardness compared to TPE-R. Returns nearly to original physical properties after 1–4 week chemical exposure and subsequent drying.
CE marked (ETA-04/0044)
For high-temperature environments exceeding 250°F and the most severe chemical applications where polymer waterstops are not viable. TIG welded for splices and intersections.
Envirostop TPE-R: The NSF/ANSI Standard 61 certified version of Westec TPE-R, suitable for drinking water containment structures and ozone contact applications in potable water treatment facilities.
Physical properties — side-by-side comparison
All three Westec chemical resistant waterstop materials are manufactured to meet rigorous ASTM physical property requirements. The tables below compare key engineering properties so specifiers can quickly evaluate the trade-offs between flexibility, strength, and temperature performance.
Notable trade-offs: PE has the highest elongation (800%) but is more rigid than TPE-R. TPE-R offers the best balance of flexibility and chemical resistance for most secondary containment applications. SS provides vastly higher tensile strength but minimal elongation. Among the three materials, only stainless steel carries a published service temperature rating above 250°F — for temperatures exceeding that threshold, SS is the only option.
Profile families and geometries
Each Westec material is offered in multiple profile geometries, allowing engineers to match the right material with the right joint condition. The five primary profile families cover virtually every chemical containment scenario, from standard construction joints to expansion joints with significant movement requirements and retrofit applications joining new concrete to existing structures.
Industry-standard profile for control and expansion joints in both vertical and horizontal applications. The centerbulb accommodates joint movement equal to its inside diameter. Available in TPE-R and PE.
Designed for joints with larger movement. The thin web in the U-shaped centerbulb tears during joint movement, allowing additional expansion or differential settlement. Available in TPE-R and PE.
For sealing joints where new concrete meets existing structures. Anchored with stainless steel batten bars and tapcons, sealed with Westec 151 Novolac Gel Epoxy. Available in TPE-R, PE, and SS.
Westec’s patented Expansion Board Cap Seal system integrates waterstop, forming, expansion board, joint seal, and load transfer into a single unit. No split formwork, no sealant. Available in TPE-R and PE.
Designed for slab-on-grade joints and backfilled walls. Eliminates difficult split forming details. May have limitations joining to standard waterstops at containment area transitions. Available in TPE-R only.
Grommets included: Westec TPE-R and PE 6″ and 9″ profiles are pre-punched in the outermost rib with brass grommets on 12″ centers, providing convenient points to wire the waterstop to reinforcement. Properly securing the waterstop is critical to ensure good consolidation around the ribs and a liquid-tight seal.
Installation overview
Installation procedures vary by material — TPE-R and PE waterstops are heat-welded using a Sika Greenstreak splicing iron at elevated temperature, while stainless steel waterstops are joined using TIG welding. All Westec waterstops must be installed prior to concrete placement to ensure proper positioning and full concrete consolidation around the profile. The sequence below covers the general steps; refer to Sika’s profile-specific installation guides for detailed procedures.
Confirm material and profile selection. Verify chemical exposure, temperature, and joint movement requirements against the chosen waterstop material and profile before delivery to site.
Position the waterstop in the joint. Center the profile on the joint line, with half the profile to be encapsulated in the first pour and half projecting into the second. Use brass grommets on 6″ and 9″ profiles to wire the outer rib to reinforcement.
Heat weld TPE-R and PE splices. Use a Sika Greenstreak splicing iron set to 410°F (210°C). Follow Sika’s TPER/PE Splicing Guidelines for all field-welded transitions.
TIG weld stainless steel splices. All SS waterstop transitions, intersections, and splices must be TIG welded to maintain continuity. Factory-made fabrications are strongly recommended for all intersections and direction changes.
Anchor retrofit profiles to existing concrete. Install stainless steel batten bars and tapcons through the retrofit profile flange into the existing concrete face. Apply Westec 151 Novolac Gel Epoxy between the flange and concrete to create a fluid-tight chemical-resistant seal.
Place and consolidate new concrete. Pour and vibrate concrete carefully around the installed waterstop. Full encapsulation of the ribs is essential for liquid-tight performance — voids around the profile will compromise the chemical barrier.
Frequently asked questions
Common questions from engineers, specifiers, and contractors about chemical resistant waterstops, material selection, and installation.
Need help selecting the right chemical resistant waterstop?
Our team can help you choose the right material — TPE-R, PE, or stainless steel — and the right profile for your containment application.