Repair Systems — 03 — Facade & External Envelope
Sikaflex-11FC+ one-part polyurethane movement joint sealant
Technical product reference for Sikaflex-11FC+ one-part moisture-curing polyurethane sealant by Sika Australia — the industry standard for movement joints in masonry facades on Class 2 strata buildings. ISO 11600 F 25 LM rated, accommodates ±25% joint movement at low modulus. Gun-grade, no mixing, paintable after cure. Requires polyethylene foam backer rod and primer on porous substrates.
What is Sikaflex-11FC+ one-part polyurethane sealant?
Sikaflex-11FC+ is a one-part moisture-curing polyurethane sealant rated ISO 11600 F 25 LM — the industry standard for movement joints in masonry facades on Australian Class 2 strata buildings. Gun-grade, single-component, no mixing required. Accommodates ±25% of the joint width in movement at low modulus, meaning low stress is transmitted to the joint faces. Paintable after full cure. Requires a polyethylene foam backer rod at the joint base and primer on porous substrates.
Supplier reference — Sikaflex-11FC+ polyurethane sealant
Sikaflex-11FC+ one-part moisture-curing polyurethane sealant
Industry-standard one-part moisture-curing PU sealant — ISO 11600 F 25 LM — ±25% movement accommodation — paintable after cure — for masonry facade movement joints and control joints
Sikaflex-11FC+ — key technical data
| Attribute | Value |
|---|---|
| Supplier | Sika Australia |
| Product | Sikaflex-11FC+ |
| Components | One-part |
| Cure mechanism | Moisture-curing |
| ISO class | F 25 LM |
| Movement accommodation | ±25% |
| Shore A hardness (cured) | ~35A |
| Elongation at break | >500% |
| Service temp range | −40°C to +90°C |
| Paintable | Yes — after full cure |
| Primer required | Yes — Sika Primer-3 N on porous substrates |
| Bond breaker required | Yes — PE foam backer rod |
| Joint width:depth ratio | 2:1 |
| Traffic bearing | No |
- Masonry expansion joints and control joints at 5–6 m centres per AS 3700 requirements
- Window and door frame perimeter joints — at junction of aluminium frame and masonry surround
- Control joints in rendered masonry facades — where render is cut through to the substrate
- Specify Sikaflex-11FC+ for general masonry facade movement joint repair — one-part, familiar to contractors, widely available
- Confirm joint width meets the 6–25 mm working range — wider joints may require a different formulation
- Apply joint width:depth ratio of 2:1 — install PE foam backer rod to control depth before sealant application
- Bond breaker tape or backer rod at the joint base is mandatory — three-sided bond causes cohesive tearing failure
- Do not apply to wet joint faces — moisture on the bond face prevents adhesion
- Do not apply over existing uncured or contaminated sealant — rake out fully to sound substrate
- ISO 11600 — Classification and requirements for joint sealants — F 25 LM designates facade grade, ±25%, low modulus
- AS 3700 — Masonry Structures — movement joint spacing and sealant requirements for masonry facades
- NATSPEC worksection 05 32 00 — Sealants — project specification requirements for sealant work
- Failed, cracked or debonded polyurethane sealant in masonry facade movement joints
- Open control joints where original sealant has cured out, shrunk or pulled away from the joint face
- Perimeter joints around window and door frames where original sealant is deteriorated or absent
- Modern fired clay brick — prime porous surfaces with Sika Primer-3 N before sealant application
- Concrete masonry units and precast concrete panels — prime per TDS
- Rendered masonry facades — confirm render is cured, clean and primed before sealing
Do not confuse Sikaflex-11FC+ with:
- Sikaflex-15LM — a different Sika polyurethane sealant grade with a lower modulus formulation; confirm the correct grade for the specified joint class before ordering
- Mapeflex PU45 — a two-part chemically curing polyurethane sealant by Mapei requiring component mixing and pot-life management; not interchangeable with one-part products on standard residential facade joint repairs
- Tremco Dymonic FC — a one-part high-movement polyurethane sealant rated ±35% movement; a higher-grade product for wide or high-movement facade joints where ±25% is insufficient
- Silicone sealants — silicone is not paintable after cure; do not substitute silicone for polyurethane on joints that will receive a painted topcoat
- Polysulfide sealants — a different polymer chemistry with different adhesion and movement characteristics; not directly interchangeable with polyurethane on masonry movement joints
Disclaimer
This page provides general technical information only. Sealant selection, joint geometry, primer requirements and movement class must be confirmed against the project's joint design, substrate type and exposure conditions per ISO 11600 and AS 3700. Confirm current product data with the manufacturer TDS before specifying or applying.