--- title: "Linear Gap & Joint Fire Sealing — London, Kent, Sussex & Surrey | Flame Solutions Ltd" description: "Seal head-of-wall, deflection head, floor-to-wall and construction joints to certified detail — using tested backer and sealant systems by joint width and mov" lang: en-GB json-ld: | [ { "@context": "https://schema.org", "@type": "Organization", "@id": "https://flamesolutions.co.uk/#organization", "name": "Flame Solutions Ltd", "url": "https://flamesolutions.co.uk", "logo": "https://flamesolutions.co.uk/favicon.png", "telephone": "+447400436839", "email": "flamesolutionsltd@gmail.com", "address": { "@type": "PostalAddress", "streetAddress": "6 Byron Avenue", "addressLocality": "Coulsdon", "postalCode": "CR5 2JR", "addressRegion": "Surrey", "addressCountry": "GB" }, "founder": { "@type": "Person", "name": "Michael Sully" } }, { "@context": "https://schema.org", "@type": "WebSite", "@id": "https://flamesolutions.co.uk/#website", "url": "https://flamesolutions.co.uk", "name": "Flame Solutions Ltd", "inLanguage": "en-GB", "publisher": { "@id": "https://flamesolutions.co.uk/#organization" } }, { "@context": "https://schema.org", "@type": "Service", "@id": "https://flamesolutions.co.uk/services/linear-gap-joint-fire-sealing#service", "serviceType": "Linear Gap & Joint Fire Sealing", "name": "Linear Gap & Joint Fire Sealing", "url": "https://flamesolutions.co.uk/services/linear-gap-joint-fire-sealing", "provider": { "@type": "LocalBusiness", "@id": "https://flamesolutions.co.uk/#localbusiness", "name": "Flame Solutions Ltd", "telephone": "+447400436839", "email": "flamesolutionsltd@gmail.com", "address": { "@type": "PostalAddress", "streetAddress": "6 Byron Avenue", "addressLocality": "Coulsdon", "postalCode": "CR5 2JR", "addressRegion": "Surrey", "addressCountry": "GB" } }, "areaServed": [ { "@type": "Place", "name": "London" }, { "@type": "Place", "name": "Kent" }, { "@type": "Place", "name": "Sussex" }, { "@type": "Place", "name": "Surrey" }, { "@type": "Place", "name": "Croydon" }, { "@type": "Place", "name": "Sutton" }, { "@type": "Place", "name": "Bromley" }, { "@type": "Place", "name": "Sevenoaks" }, { "@type": "Place", "name": "Crawley" } ], "description": "Seal head-of-wall, deflection head, floor-to-wall and construction joints to certified detail — using tested backer and sealant systems by joint width and movement — so the compartment line is continuous at every junction, evidenced and recorded." }, { "@context": "https://schema.org", "@type": "FAQPage", "mainEntity": [ { "@type": "Question", "name": "How much does linear gap sealing cost?", "acceptedAnswer": { "@type": "Answer", "text": "Priced by linear metre and joint type. Send a scope or an FRA extract with joint locations and you'll get a fixed quotation." } }, { "@type": "Question", "name": "How long does the work take?", "acceptedAnswer": { "@type": "Answer", "text": "Head-of-wall runs on a residential floor are typically days per floor; small commercial scopes complete in a single visit." } }, { "@type": "Question", "name": "Do you provide a warranty on the sealed joints?", "acceptedAnswer": { "@type": "Answer", "text": "No product warranty is offered. The certified sealant system's own test evidence is the assurance; our deliverable is evidenced installation to the tested detail." } }, { "@type": "Question", "name": "How long does a sealed joint last?", "acceptedAnswer": { "@type": "Answer", "text": "Correctly installed to the movement class of the joint, the seal performs for the life of the construction. 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[Cookie policy](/cookie-policy) OK 1. [Home](/) 2. [Services](/services) 3. Linear Gap & Joint Fire Sealing ![Linear gap fire sealing bead along a head-of-wall junction between plasterboard and concrete soffit](/assets/linear-gap-sealing-C_nXQ1WD.jpg) [← All services](/services) # Linear Gap & Joint Fire Sealing Head-of-Wall, Floor-to-Wall & Construction Joints London, Kent, Sussex & Surrey Seal head-of-wall, deflection head, floor-to-wall and construction joints to certified detail — using tested backer and sealant systems by joint width and movement — so the compartment line is continuous at every junction, evidenced and recorded. [Request Estimate](/contact) [07400 436839](tel:+447400436839) 5 years' passive fire experience. Every joint sealed to a tested detail and recorded. Passive fire experience 5 years Third-party certification BM TRADA (via Sully Form Ltd) Employers' liability £10M Public liability £5M Accreditations Constructionline Silver · SafeContractor · SIPS Service overview ## What this service is — and when you need it. What it is Installation of certified backer and sealant systems into linear gaps and construction joints — head-of-wall, floor-to-wall, wall-to-wall and slab junctions — sized to joint width, movement and required fire rating. Who it's for HRB duty holders, housing associations, principal contractors, healthcare estates, fit-out contractors and duty holders closing out FRA compartmentation actions on linear defects. When it's needed During refurbishment, on new-build handover, after FRA surveys flag open head-of-wall or junction defects, and when compartment walls have been altered or extended. Why a specialist matters Linear gaps are the most commonly missed compartmentation defect. A perfect compartment wall with an unsealed strip above the head is not a compartment wall at all. Sealing to a tested detail closes the line at the junction where it most often fails. What happens if this is ignored ## The consequence of leaving it. - An unsealed head-of-wall lets fire and smoke pass directly into the ceiling void — the fastest route between compartments. - Movement joints that crack the sealant on first thermal cycle behave as if unsealed. - Linear gap failures are one of the top findings on FRA compartmentation surveys — leaving them open drives repeat remedials. Common mistakes ## What we see go wrong. - Filling a head-of-wall joint with generic silicone or acoustic sealant — not a fire sealing system. - Ignoring joint movement — a rigid seal on a deflection head detail cracks off in the first year. - Skipping the backer rod, or using the wrong depth — the sealant doesn't achieve its tested performance. - No dimensional record — the assessor can't verify the sealed joint width matches the certified system. Our process ## A step-by-step system, from survey to handover. 1. Step 1 Joint survey Every joint on the scope measured for width, depth and movement class, and logged against a floor plan. 2. Step 2 System selection Certified backer and sealant system paired to joint width, movement class, substrate and required fire rating. 3. Step 3 Preparation and installation Joint prepared and cleaned, backer rod set to the certified depth, sealant tooled to the certified profile. 4. Step 4 Dimensional and photo record Joint width and sealed depth recorded, and completed joint photographed against the location reference. 5. Step 5 Handover pack Record of Insulation, product datasheets and location-referenced photo and dimension pack handed over for the safety file. Why clients choose Flame Solutions ## Specific outcomes, not vague promises. Continuous compartment line at every junction The compartment wall meets the slab — sealed to a tested detail — instead of stopping short. Movement handled correctly Deflection head details use sealants and geometry rated for the joint's movement, so the seal doesn't crack off. Evidence per joint Each joint photographed and dimensioned against a location, ready for FRA re-inspection. Fewer repeat visits Correct system first time means the joint doesn't reappear on next year's remedial list. Coordinated with wall works Sealed alongside compartmentation and stopping, not stitched together across separate visits. Defensible paperwork Record of Insulation and datasheet pack that survives assessor and insurer scrutiny. In detail ## Materials, methods and where each applies. The technical detail behind how linear gap & joint fire sealing is scoped, specified and installed to certified detail. Head-of-wall and deflection head joints Floor-to-wall and wall-to-wall junctions Certified backer rod and sealant systems ### Head-of-wall and deflection head joints The join between the top of a compartment wall and the slab above is often incomplete. Where the wall is designed to accommodate slab deflection, the joint needs a system rated for that movement class — otherwise the sealant cracks on first thermal cycle. System selection depends on joint width, movement and substrate on both sides. ### Floor-to-wall and wall-to-wall junctions Joints between different construction elements — a partition meeting a party wall, a concrete slab meeting a stud wall — each need a certified detail specific to the substrate combination and joint width. ### Construction joints in concrete and blockwork Movement and construction joints running through slabs and walls need sealing that respects the joint's structural function while restoring the fire rating. Mortar-plus-sealant and specialised joint sealing systems are selected against the certified schedule. ### Sealant types and backer rod selection Not every fire sealant is rated for every joint width. Sealant depth to width ratio, backer rod type (open- vs closed-cell) and priming requirements all come from the tested system datasheet. ### Coordination with compartmentation and stopping Linear gap work is almost always adjacent to compartment wall repair and service penetration sealing. Delivering all three from one team removes the joins where responsibility usually splits. ### What we do not offer We do not offer a product warranty on the sealed joint. The certified sealant system's own third-party test evidence is the assurance; our commitment is to install to the tested schedule and provide evidence. Related services [Certified Fire Door Installation](/services/fire-door-installation)[Fire Door Maintenance & Repairs](/services/fire-door-maintenance-repairs)[Fire Stopping Services](/services/fire-stopping)[Compartmentation](/services/compartmentation) Serving [London](/areas/london), [Kent](/areas/kent), [Surrey](/areas/surrey), [Croydon](/areas/croydon) . See [all services](/) or [get in touch](/contact). Frequently asked ## Straight answers on cost, timing and process. How much does linear gap sealing cost? + Priced by linear metre and joint type. Send a scope or an FRA extract with joint locations and you'll get a fixed quotation. How long does the work take? + Head-of-wall runs on a residential floor are typically days per floor; small commercial scopes complete in a single visit. Do you provide a warranty on the sealed joints? + No product warranty is offered. The certified sealant system's own test evidence is the assurance; our deliverable is evidenced installation to the tested detail. How long does a sealed joint last? + Correctly installed to the movement class of the joint, the seal performs for the life of the construction. Failures usually trace back to the wrong sealant for the joint movement, or an incorrect backer. Can you work in occupied buildings? + Yes — access is phased and dust is controlled. Do you seal around metal deck and profiled slab details? + Yes — profiled slab head-of-wall details have their own tested systems and we specify accordingly. Can this be combined with other passive fire scope? + Yes — linear gap sealing is usually delivered alongside penetration stopping and compartmentation repair as one coordinated package. Which areas do you cover? + London, Kent, Sussex, Surrey and surrounding boroughs including Croydon, Sutton, Bromley, Sevenoaks and Crawley. Do you handle FRA close-out on linear gap actions? + Yes — evidence per joint, referenced back to the FRA action number. ## Get a fixed quotation for linear gap & joint fire sealing. Send the FRA action list, drawings or a short scope description. You'll speak to Michael directly — not a call centre — and get a scoped, priced programme back. [07400 436839](tel:+447400436839)[Contact page](/contact) Delivered by Michael Sully — 5 years' passive fire experience. BM TRADA third-party certification held via Sully Form Ltd. Insured to £10M employers' / £5M public liability. ## Ready to scope your linear gap & joint fire sealing works? Send the FRA or a short brief. You'll get a priced, evidenced programme back — not a template quotation. [Request Estimate](/contact) [07400 436839](tel:+447400436839) ![Flame Solutions Ltd](/__l5e/assets-v1/8937fb61-d54f-4b77-aea7-a3f11a843ae3/flame-solutions-logo.png) Certified passive fire protection — fire doors, fire stopping and compartmentation — led by BM TRADA third-party certified specialist Michael Sully. [07400 436839](tel:+447400436839) [flamesolutionsltd@gmail.com](mailto:flamesolutionsltd@gmail.com) 6 Byron Avenue, Coulsdon, CR5 2JR Monday – Saturday: 7:00am – 7:00pm [](https://www.instagram.com/flamesolutionsltd/) Services - [Certified Fire Door Installation](/services/fire-door-installation) - [Fire Door Maintenance & Repairs](/services/fire-door-maintenance-repairs) - [Fire Stopping Services](/services/fire-stopping) - [Compartmentation](/services/compartmentation) - [Fire Door Surveys](/services/fire-door-surveys) - [FRA Passive Fire Repairs](/services/fra-passive-fire-repairs) - [Service Penetration Fire Sealing](/services/service-penetration-fire-sealing) - [Linear Gap & Joint Fire Sealing](/services/linear-gap-joint-fire-sealing) - [Fire-Rated Air Transfer Grille Installation](/services/fire-rated-air-transfer-grille-installation) Service Areas - [London](/areas/london) - [Kent](/areas/kent) - [Sussex](/areas/sussex) - [Croydon](/areas/croydon) - [Surrey](/areas/surrey) - [Sutton](/areas/sutton) - [Bromley](/areas/bromley) - [Sevenoaks](/areas/sevenoaks) - [Crawley](/areas/crawley) Company - [About](/about) - [Our Work](/our-work) - [Reviews](/reviews) - [Contact](/contact) - [Privacy Policy](/privacy-policy) - [Terms & Conditions](/terms-conditions) - [Cookie Policy](/cookie-policy) © 2026 Flame Solutions Ltd. Company registered in England & Wales. BM TRADA, Constructionline Silver, SafeContractor and SIPS credentials are held by Michael Sully, registered under our associated company Sully Form Ltd. No warranty is offered. [Call](tel:+447400436839)[Request Estimate](/contact)