Sika SikaSeal-623 Fire+
A single-component intumescent graphite sealant that reseals the fire and smoke rating of walls and floors wherever combustible pipes, insulated services and conduits pass through.
What is it?
A ready-to-use, single-component intumescent sealant based on expandable graphite, supplied in anthracite. Under fire it swells up to around 25 times its volume to crush and seal the gap left when a burning plastic pipe softens.
Where is it used?
Service penetrations through fire-rated masonry and concrete walls and floors: soil and waste pipes, insulated pipework, electrical conduits and small cable groupings in MEP risers, basements and compartment lines.
Why use it?
It restores up to 4 hours of fire resistance to a penetration and adds acoustic sealing in one gun-applied operation, with no primer, no mixing and full CE/ETA and UL-EU backing.
How is it applied?
Gun-applied straight from a 300 ml cartridge or 600 ml foil pack into a clean, backed joint, then tooled smooth. It adheres without primers or activators.
About Sika SikaSeal-623 Fire+
On paper a firestop penetration seal looks trivial, but it is one of the details a fire consultant will fail a building on. When a plastic soil pipe or an insulated service passes through a rated wall or slab, the pipe itself becomes the weak point: in a fire it softens, melts back and leaves an open hole for flame and smoke to travel between compartments. SikaSeal-623 Fire+ is Sika’s answer to exactly that gap. It is a single-component sealant loaded with expandable graphite, and the moment it is heated it intumesces, swelling to roughly 25 times its original volume so it fills and chokes the void the collapsing pipe leaves behind, holding the compartment line for up to four hours depending on the tested configuration.
For a contractor working to a tight programme, the appeal is that it behaves like an ordinary sealant on the tools. It comes ready to use in a familiar anthracite cartridge, needs no primer or activator on most substrates, and is simply gunned in and tooled off. There is no two-part mixing, no pot life to race against, and the same bead that delivers the fire rating also gives useful acoustic sealing across the penetration. Because it carries CE marking under a European Technical Assessment and a UL-EU classification, it also gives the consultant and the certifying authority a documented, third-party-tested basis for signing the detail off rather than relying on a site-improvised mortar or foam.
The technical insight
The performance comes from expandable graphite carried in the sealant matrix. At normal temperatures the bead is inert and flexible, so it moves with the joint and seals against smoke and sound. When temperature climbs in a fire, the graphite flakes exfoliate and the material expands hard against the penetrating service, generating pressure as it grows to around 25 times its volume. That expansion is the mechanism: as a combustible pipe softens and shrinks back, the intumescent char pushes inward to occupy the space and form a dense, insulating plug that resists the passage of flame and hot gas. Because the reaction is thermally triggered rather than chemically cured, the seal only activates when it is needed, and the tested wall-and-floor configurations in the ETA translate that behaviour into a defined fire-resistance period of up to four hours.
Where it is used
- Sealing combustible plastic soil, waste and vent pipe penetrations through fire-rated walls and floors
- Firestopping insulated pipework where the insulation is combustible or partially combustible
- Sealing electrical conduits and small cable bundles passing through compartment walls and slabs
- Reinstating the fire rating of MEP riser penetrations in multi-storey and high-rise buildings
- Compartmentation sealing in basements, plant rooms and car parks
- Fire and smoke sealing of service openings in hospitals, hotels and commercial fit-outs
- Acoustic sealing of penetrations where sound transfer between rooms or floors is a concern
- Remedial firestopping of existing openings found open during fire-safety audits
Key advantages
- Restores up to 4 hours of fire resistance to combustible service penetrations
- Highly intumescent, expanding up to around 25 times its volume to seal a collapsing pipe
- Single-component and ready to use with no mixing or measuring on site
- Adheres to common substrates without a separate primer or activator
- Provides acoustic insulation across the penetration in the same operation
- Backed by CE marking under a European Technical Assessment and a UL-EU classification
- Familiar cartridge and foil-pack format applied with a standard sealant gun
- Low-emission credentials suited to sealed and occupied interiors
Limitations & considerations
- An interior firestopping product, not a general-purpose weatherproofing or facade sealant
- The rated performance is only valid for penetration configurations that match a tested ETA detail, including correct backing and joint dimensions
- Not intended for permanent water immersion, water-pressure joints, sanitary joints or structural expansion joints
- Should not be used over bituminous substrates, natural rubber, EPDM or materials that leach oils or plasticisers
- Application is limited to a controlled temperature window and requires the substrate to be above dew point
- Anthracite colour only, so it needs finishing or covering where appearance matters
Selection & best practice
Treat the penetration as a system, not just a bead of sealant. Start by confirming the wall or floor construction and the service type against an ETA-tested configuration, and size the annular gap and any backing material accordingly rather than over-filling. Clean the substrate and the service back to sound, dust-free material; the sealant bonds without a primer on most surfaces, but oil, loose particles and unsuitable substrates such as bitumen or EPDM must be ruled out. Work within the ambient and substrate temperature window of roughly +5 C to +30 C and keep the surface at least 3 C above the dew point so condensation does not spoil adhesion. Install any required mineral-wool or backing so the seal depth matches the tested detail, gun the anthracite bead fully into the joint, then tool it firm to compact the material and remove voids. Clean tools with water immediately after use, before the sealant skins. Keep the batch and ETA reference with the project firestopping records so the detail can be verified during inspection.
Specifications
| Product type | Single-component intumescent firestop sealant |
| Chemical base | Expandable (intumescent) graphite |
| Colour | Anthracite |
| Density | ~1.5 kg/l (ISO 1183-1) |
| Fire resistance | Up to 4 hours (EN 13501-2, configuration-dependent) |
| Intumescent expansion | Up to ~25 times original volume |
| Service temperature | -15 C to +75 C |
| Application temperature | +5 C to +30 C (ambient and substrate), min. +3 C above dew point |
| Certification | CE / European Technical Assessment (ETA) and UL-EU classification |
| Packaging | 300 ml cartridge and 600 ml foil pack (12 per box) |
Industry use cases
High-rise & Commercial
Reinstating up to 4-hour compartment ratings at plastic pipe and conduit penetrations in MEP risers across multi-storey towers and offices.
Healthcare
Fire and smoke sealing of insulated services and conduit penetrations in hospitals, where compartmentation and acoustic separation both matter.
Hospitality & Fit-out
Sealing service openings between hotel rooms and floors, combining fire rating with useful acoustic sealing in a single bead.
Infrastructure & Basements
Compartmentation of plant rooms, car parks and basement service runs where combustible pipes cross rated walls and slabs.
Fire-safety remediation
Closing open or poorly sealed penetrations flagged during passive-fire-protection audits of existing buildings.
Frequently asked questions
What exactly does SikaSeal-623 Fire+ do?
How much fire resistance does it provide?
Does it need a primer or mixing?
What pack sizes are available and what colour is it?
Can I use it outside or underwater?
Is it certified for use on projects in India?
How we position Sika SikaSeal-623 Fire+
SikaSeal-623 Fire+ sits in Sika’s passive fire protection range and is the go-to intumescent sealant for combustible pipe and conduit penetrations. Where a project instead needs to firestop a large linear gap or a mixed-service opening, pair it with a Sika fire-rated foam or a coated mineral-wool batt system, and use a suitable Sikaflex or SikaHyflex sealant for the non-fire movement and facade joints on the same job. For the broader waterproofing and joint-sealing scope around wet areas and basements, Space Arc also supplies Fosroc, Dr. Fixit and STP systems; our team can specify the correct firestop configuration and matching accessories so the tested detail is reproduced on site rather than improvised.
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