Repair Systems — 03 — Facade & External Envelope
Polysulfide sealant systems
Technical product reference for polysulfide sealant systems used in facade joint remediation on Australian Class 2 strata buildings. Covers product classification, system selection, substrate compatibility and brand comparisons for two-part polysulfide sealants used in specialist facade and immersed joint applications.
What are polysulfide sealant systems?
Polysulfide sealants are two-part elastomeric sealants based on liquid polysulfide polymer chemistry. They were among the first elastomeric joint sealants used in building construction, gaining widespread use in the 1950s and 1960s before polyurethane and silicone sealants became dominant. Polysulfide sealants are characterised by excellent chemical resistance, particularly to fuels, oils, solvents and water — making them suitable for applications where polyurethane or silicone sealants are inadequate.
Product Reference
3 products — 3 brands — polysulfide joint sealant systems — scroll to view all
Fosroc Thioflex 600
Two-part polysulfide sealant — facade / water-retaining structures
System Description
Fosroc Thioflex 600 is a two-part polysulfide joint sealant used in Australian construction for facade movement joints, water-retaining structure joints, basement joints and other applications requiring chemical resistance or suitability in immersed conditions. Polysulfide sealants have been used in Australian construction for decades and are the traditional choice for water-retaining structures, potable water tanks and fuel-resistant applications. Thioflex 600 requires mixing of A and B components on site and must be applied within the pot life window. Primer (Fosroc Nitobond or substrate-specific primer) is required on most substrates — confirm with Fosroc Australia technical. In facade remediation, polysulfide has largely been superseded by polyurethane sealants for most movement joint applications, but remains the correct choice for specialist immersed and chemical-resistance applications. TODO: owner confirm — confirm current Australian product designation, mixing ratio, pot life and primer requirements with Fosroc Australia technical.
Technical Properties
- Two-part — A+B mixed on site — chemically curing
- Excellent chemical resistance — suitable for immersed joints and water-retaining structures
- Fuel-resistant formulation available — confirm product variant with Fosroc
Limitations
- Older technology — polyurethane sealants are generally preferred for facade movement joints in current Australian practice
- Two-part — defined pot life — more complex site application than one-part systems
- Primer required on most substrates
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
Sika Sikaflex-2AP
Two-part polysulfide sealant — specialist immersed / chemical-resistance
System Description
Sika manufactures polysulfide sealant products for specialist construction applications including water-retaining structures, immersed joints, chemical plant and fuel-resistant applications. Polysulfide sealants from Sika are used in Australian construction where chemical resistance, fuel resistance or suitability for permanently immersed conditions is required — applications where polyurethane sealants are not appropriate. Confirm the current Australian product designation and product range with Sika Australia technical, as polysulfide products may be marketed under different product codes or may have been updated. Primer is required on all substrates — confirm the correct Sika primer for the specific substrate with Sika Australia technical. TODO: owner confirm — confirm current product designation, mixing ratio, pot life, movement class and primer requirements with Sika Australia.
Technical Properties
- Two-part polysulfide — chemically curing — independent of moisture
- Chemical resistance — fuel resistance — immersed joint suitability
- Sika national distribution and technical support
Limitations
- Polyurethane is generally preferred over polysulfide for routine facade movement joint applications in current Australian practice
- Primer required on all substrates
- Two-part — defined pot life — trained applicator required
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
Tremco Thiokol 2235M
Two-part polysulfide sealant — fuel-resistant / chemical-resistance grade
System Description
Tremco Thiokol 2235M is a two-part polysulfide joint sealant known for its chemical and fuel resistance, historically used in aviation and industrial construction as well as building facade and water-retaining structure joints. Polysulfide sealants of this type are specified where resistance to fuels, solvents or chemical exposure is required in addition to movement accommodation — making them suitable for carpark joints, fuel-exposed areas and chemical plant construction. In Australian facade remediation, polysulfide remains the correct choice for specialist immersed and chemical-resistance applications. Primer is required on most substrates — confirm primer selection with Tremco Australia technical. TODO: owner confirm — confirm current Australian product designation, availability, mixing ratio, pot life and primer requirements with Tremco Australia.
Technical Properties
- Two-part polysulfide — fuel resistant — chemical resistant
- Suitable for aviation fuel-exposed joints and carpark movement joints
- Suitable for immersed and water-retaining structure joints
Limitations
- Specialist product — not required for routine facade movement joint applications
- Polysulfide largely superseded by polyurethane for non-chemical-resistance facade applications
- Two-part — defined pot life — trained applicator required
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
System Comparison
Side-by-side comparison of polysulfide sealant systems. Confirm all product selections against current manufacturer TDS.
| Product system | Brand | Components | Chem. resist. | Immersed | Movement | Primary use |
|---|---|---|---|---|---|---|
| Thioflex 600 | Fosroc | Two | Excellent | Yes | Confirm TDS | Facade joints, water-retaining structures, basement joints, immersed applications |
| Sikaflex-2AP | Sika | Two | Confirm TDS | Confirm TDS | Confirm TDS | Specialist immersed and chemical-resistance applications — confirm with Sika Australia |
| Thiokol 2235M | Tremco | Two | Excellent — fuel resistant | Yes | Confirm TDS | Fuel-resistant joints, aviation, carpark and chemical-exposure joint applications |
Do not confuse polysulfide sealant with:
- Polyurethane sealant (different chemistry — PU is the more common choice for facade movement joints in Australian strata remediation — listed on the PU sealant pages)
- Neutral cure silicone sealant (different chemistry — silicone is superior for UV-exposed glazing and aluminium frame perimeter sealing — listed on the neutral cure silicone page)
- Bitumen-based joint filler (different material — bituminous products are used in road and civil construction, not facade remediation)
- Cement-based grout (rigid — no movement accommodation — not a sealant system)
- Epoxy joint filler (rigid — no movement accommodation — not suitable for movement joints)
Disclaimer
This page provides general technical information only. Final product selection must be confirmed against the current manufacturer technical data sheet, project specification, substrate condition, exposure classification and applicator warranty conditions. Products marked TODO: owner confirm require verification before specifying.