Sika Sikaflex-11 FC+
One-part i-Cure polyurethane that bonds and seals in a single cartridge, with +/-35% movement capacity and CE marking for facade and pedestrian joints.
What is it?
A single-component, elastic polyurethane adhesive-and-sealant built on Sika’s i-Cure moisture-curing technology, gun-applied straight from a 300 ml cartridge or 600 ml foil pack.
Where is it used?
Facade and connection joints, window and door perimeters, precast panel bonding, and general fixing of metal, timber, stone and ceramic on both interior and exterior work.
Why use it?
It replaces separate adhesives and sealants in one product, accommodates +/-35% joint movement, and carries CE marking to EN 15651-1 and -4 plus an ASTM C920 class 35 rating.
How is it applied?
Onto clean, sound substrates between +5 C and +40 C, tooled within the 70-minute skin time, using a backing rod and a 2:1 width-to-depth ratio for movement joints.
About Sika Sikaflex-11 FC+
Sikaflex-11 FC+ has been a workhorse on Indian sites for one simple reason: it does two jobs from a single tube. As an adhesive it fixes precast elements, skirtings, thresholds, cover strips and cladding trims without mechanical fasteners; as a sealant it closes perimeter and connection joints that have to breathe as the structure moves. Because it is built on Sika’s i-Cure polyurethane, it cures with atmospheric moisture into a tough, permanently elastic rubber rather than a hard, brittle line. That combination of grab and give is why specifiers reach for it on facades, fit-outs and repair work alike.
For a contractor, the practical appeal is fewer products on the trolley and fewer things to get wrong. One cartridge bonds most common construction substrates – concrete, masonry, cast and natural stone, ceramic, timber, metal and glass – usually without a primer, and the same cartridge seals a 10 to 35 mm movement joint. It is low-emission (GEV-Emicode EC1PLUS, French A+) so it is safe for enclosed interiors, and it can be over-painted with most water-based systems once cured. Delivered in concrete-grey and other locally stocked shades, it disappears into typical grey concrete and mortar work without a jarring joint line.
The technical insight
The performance comes down to how i-Cure polyurethane cures and how it behaves once set. Moisture from the air triggers a controlled reaction from the surface inwards at roughly 3.5 mm per 24 hours at 23 C and 50% humidity, so a normal joint bead skins in about 70 minutes and builds strength steadily rather than flashing off. The cured polymer reaches only about Shore A 37 hardness with around 700% elongation at break and roughly 80% elastic recovery, which is the mechanical signature of a sealant that stretches with a moving joint and springs back instead of tearing. Its low secant modulus (about 0.60 N/mm2 at 100% elongation) means it transfers very little stress back into the joint edges, protecting weaker substrates like render or reconstituted stone. That same low-modulus elasticity is what earns the +/-35% movement rating to ASTM C 719 – the joint can open and close by more than a third of its designed width across the -40 C to +80 C service range without the seal debonding or splitting. Because it needs airborne moisture to cure, it must never be used as a full-surface bond line where the core would be starved of moisture and stay uncured; that is a chemistry limit, not a workmanship one.
Where it is used
- Sealing facade movement and connection joints on concrete and masonry buildings (CE marked to EN 15651-1)
- Sealing joints in pedestrian walkways and paved areas (CE marked to EN 15651-4)
- Perimeter sealing around window and door frames in concrete and masonry openings
- Bonding precast concrete, cast stone and masonry elements without mechanical fixings
- Fixing skirtings, cover strips, thresholds, metal profiles and cladding trims in fit-outs
- Bonding and sealing ceramic, timber, metal and glass components in industrial interiors
- Sealing vibration-prone joints around plant, equipment bases and service penetrations
- General bonding and joint-sealing in residential renovation and building repair
Key advantages
- One product does both jobs – structural-grade elastic bonding and movement-joint sealing
- High +/-35% movement capability (ASTM C 719) for demanding facade and connection joints
- Bonds most construction substrates without surface pre-treatment, cutting priming steps
- CE marked to EN 15651-1 and -4, plus ASTM C920 class 35 – specification-ready credentials
- Very low emissions (GEV-Emicode EC1PLUS, French A+), suitable for sealed interiors
- Good weathering and mechanical resistance with a wide -40 C to +80 C service range
- Over-paintable with most water-based coatings once fully cured
- Convenient 300 ml cartridge and 600 ml foil-pack formats for standard guns
Limitations & considerations
- Not for full-surface or full-bed bonding – the buried core may never cure without airborne moisture
- Overhead or heavy components need mechanical fixings, and heavy elements need temporary support until cured
- Joints must fall within the 10-35 mm width band; joints 10 mm or narrower are non-movement crack-control only
- Paints and coatings must be trial-tested first – non-flexible paint films can crack over the flexible bead
- White and light shades can discolour under UV, chemicals or heat (aesthetic only, no loss of performance)
- Reconstituted, cast or natural stone should be checked with Sika Technical Services before use to avoid staining
Selection & best practice
Work to clean, sound, dry substrates and keep both ambient and substrate temperatures between +5 C and +40 C, with the substrate at least 3 C above dew point to avoid condensation under the bead. For best flow, condition the cartridge to around +20 C before gunning. On movement joints install a closed-cell polyethylene backing rod to set depth and prevent three-sided adhesion, and hold a 2:1 width-to-depth ratio for facade joints. Tool the bead firmly within the roughly 70-minute skin time to wet out both faces, and where adhesion or paint compatibility is uncertain – or on natural and reconstituted stone – run a small preliminary trial first. Let the joint cure at about 3.5 mm per 24 hours before subjecting it to full movement, and always add mechanical support for overhead or heavy bonded elements.
Specifications
| Chemical base | 1-part i-Cure technology polyurethane |
| Movement capability | +/-35% (ASTM C 719) |
| Elongation at break | ~700% (ISO 37) |
| Tensile strength | ~1.5 N/mm2 (ISO 37) |
| Shore A hardness | ~37 after 28 days (ISO 868) |
| Elastic recovery | ~80% (ISO 7389) |
| Skin (tack-free) time | ~70 min at +23 C / 50% r.h. |
| Curing rate | ~3.5 mm / 24 hours at +23 C / 50% r.h. |
| Service temperature | -40 C min. / +80 C max. |
Industry use cases
Facade and building envelope
Sealing movement and connection joints between concrete and masonry panels, curtain-wall abutments and cladding interfaces, where the +/-35% rating and EN 15651-1 CE marking are specified.
Fit-out and interiors
Bonding skirtings, thresholds, cover strips, metal profiles and ceramic or timber trims, with EC1PLUS low emissions making it safe for enclosed, occupied spaces.
Precast and prefab
Elastic bonding of precast concrete and cast-stone elements without visible mechanical fixings, used with temporary support for heavier units until cure.
Doors, windows and glazing
Perimeter sealing of frames in concrete and masonry openings, and bonding of glass and aluminium components in industrial fabrication.
Industrial and plant
Sealing vibration-prone joints around equipment bases, plant rooms and service penetrations, using the low-modulus flexibility to absorb cyclic movement.
Frequently asked questions
Is Sikaflex-11 FC+ an adhesive or a sealant?
What movement can the joint take?
Does it need a primer?
Can it be painted over?
What pack sizes and colours are available?
Why can’t I use it as a full-surface glue?
How we position Sika Sikaflex-11 FC+
Sikaflex-11 FC+ is Sika’s go-to general-purpose bond-and-seal cartridge, and it sits within a wider Sika joint-sealing range we stock. Where a facade movement joint is the priority rather than bonding, Sikaflex PRO-3 is the dedicated low-modulus PU facade sealant; for sanitary, glazing and high-UV joints look to Sikasil silicone sealants; and for heavy-duty structural and elastic bonding, Sikaflex-221 or the SikaBond adhesive family are the natural step up. Across our other brands, engineers often compare it with MS-polymer sealants such as Fosroc Nitoseal MS600 or Dr. Fixit / STP joint sealants; the honest distinction is chemistry and movement – Sikaflex-11 FC+ is a paint-over-friendly PU rated to +/-35%, while MS-polymer options trade a little movement for lower staining risk and easier over-painting on natural stone. Talk to our team about the substrate and joint movement and we will match the right product rather than default to one.
Fosroc Nitoseal MS600 — Specify the Fosroc MS-polymer option when the joint sits against natural stone or highly porous facades where staining and over-painting matter more than the extra movement, since it is non-staining and paints readily, though it is rated to a lower +/-25% movement than Sikaflex-11 FC+.
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