Fosroc Nitoseal SL
A two-part, pouring-grade polyurethane joint sealant that self-levels into horizontal floor joints and stands up to forklift traffic, oils and daily wash-downs.
What is it?
A two-component, self-levelling polyurethane sealant supplied as a base and a separate colour hardener that are mixed on site and poured directly into horizontal joints.
Where is it used?
Saw-cut and construction joints in industrial concrete floors, warehouses, food-processing halls, cold stores, loading yards and pavement slabs.
Why use it?
It flows level on its own, bonds to clean concrete arrises and forms a tough, semi-flexible seal that carries wheel loads without tearing or slumping.
How is it applied?
Clean and dry the joint, prime with Nitoprime, fit a backer rod in deeper joints, then pour the mixed sealant and let it self-level flush with the slab.
About Fosroc Nitoseal SL
Nitoseal SL is Fosroc’s self-levelling answer to the problem that ordinary gun-grade sealants struggle with on floors: horizontal joints that see constant wheeled traffic. It is a two-part system in which a polyurethane base is combined with a separate coloured curing agent. Once mixed, the material stays fluid long enough to be poured straight from the container into the joint, where it finds its own level and cures to a tough, resilient seal with a controlled degree of flexibility. That combination of pourability and toughness is what makes it a specifier’s default for factory and warehouse slabs, where the sealant has to protect the concrete arris every time a forklift wheel crosses the joint.
For engineers used to the wider Nitoseal family, this is the pouring-grade cousin of the gun-applied polyurethanes. The self-levelling grade is formulated to be load-bearing at the joint edge rather than simply weather-tight, so it suits interiors where hygiene, cleanability and mechanical abuse all matter at once. Space Arc supplies Nitoseal SL along with its companion Nitoprime primer and backer rod, and our applicators can execute the joint preparation, priming and pour as a single package on projects across Delhi NCR and the rest of India.
The technical insight
The performance comes from the cured polyurethane’s balance of hardness and elasticity. At a Shore A hardness in the region of 15 to 25 the seal is firm enough to support the concrete arris under a wheel load, yet still elastic enough to flex as the slab expands and contracts. Fosroc rates the material for movement of roughly 10% of the joint width, so the joint has to be designed and cut to a width that keeps total shrinkage and thermal movement inside that envelope. Because it is poured rather than gunned, the sealant wets out the joint walls completely and self-levels to a uniform, flush finish with no tooling — which is exactly why it holds up under repeated trafficking where a hand-tooled bead would eventually be plucked out.
Where it is used
- Sealing saw-cut control joints in industrial concrete floor slabs
- Construction (day-work) joints between successive slab pours
- Warehouse and distribution-centre floors under constant forklift and pallet-truck traffic
- Food and beverage processing halls where floors are regularly washed down
- Cold stores and refrigerated warehouse floors
- Vehicle maintenance workshops and service bays exposed to oils and fuels
- Internal loading bays, packing halls and heavy-duty manufacturing floors
- Concrete pavement and hardstanding joints subject to wheeled loads
Key advantages
- Self-levelling pouring grade fills horizontal joints uniformly with no tooling
- Load-bearing at the joint arris, protecting slab edges from wheel impact
- Good resistance to mineral oils, hydrocarbon fuels and cleaning chemicals
- Tough yet semi-flexible cured seal that accommodates normal slab movement
- Bonds well to clean, dry concrete when correctly primed
- Two-part system with a coloured hardener gives clear visual confirmation of thorough mixing
- Available in a choice of colours to suit floor finishes
- Suited to Indian and hot-climate service conditions
Limitations & considerations
- Self-levelling grade is for horizontal joints only, not vertical or overhead work
- Movement capability is modest at about 10% of joint width, so it is not for high-movement expansion joints
- Joint walls must be clean, dry and correctly primed or adhesion will fail
- Being two-part, it needs accurate on-site mixing and has a limited working time once combined
- Wider or deeper joints require a closed-cell backer rod to control sealant depth
- Traffic must be kept off the joint until the sealant has cured sufficiently
Selection & best practice
Design the joint so total shrinkage and thermal movement stays within about 10% of the joint width, and keep the sealant to a sensible width-to-depth ratio rather than over-filling deep joints. Saw-cut or rout the joint clean, then make sure both faces are dry and free of dust, laitance, curing compound and oil. Prime the joint walls with Nitoprime and install a closed-cell polyurethane backer rod in deeper joints to set the correct depth and prevent three-sided adhesion. Mix the base and coloured hardener fully until the colour is uniform, then pour without delay and let the material self-level flush with the floor. Protect the joint from foot and wheeled traffic until it has cured, and mask adjacent surfaces where a crisp edge is wanted.
Specifications
| Type | Two-component self-levelling (pouring-grade) polyurethane joint sealant |
| Consistency | Self-levelling liquid, poured directly into horizontal joints |
| Shore A hardness | Approx. 15-25 (semi-flexible, load-bearing) |
| Movement accommodation | Approx. 10% of joint width |
| Primer | Nitoprime (as specified for the substrate) |
| Backing | Closed-cell polyurethane backer rod for deeper joints |
| Chemical resistance | Good against mineral oils, hydrocarbon fuels and common cleaning agents |
| Colour | Range of colours; separate coloured hardener for mixing control |
| Application | Horizontal floor joints only |
Industry use cases
Warehousing & Logistics
Seals saw-cut floor joints in distribution centres so slab edges survive continuous forklift and pallet-truck traffic.
Food & Beverage Processing
Provides a flush, cleanable joint seal in wash-down production halls where hygiene and chemical exposure are constant.
Cold Storage
Handles the floor joints of refrigerated warehouses and cold stores that run under heavy internal traffic.
Manufacturing & Automotive Workshops
Protects joint arrises in heavy manufacturing bays and vehicle service areas exposed to oils, fuels and wheel loads.
Pavements & Hardstandings
Seals concrete pavement and yard slab joints where trafficked, self-levelling performance is needed.
Frequently asked questions
Is Nitoseal SL the same as Fosroc Nitoseal PU280?
Can I use it in vertical or wall joints?
How much movement can the joint take?
Do I need a primer and a backer rod?
How soon can traffic run over it?
Can Space Arc apply it, or only supply the material?
How we position Fosroc Nitoseal SL
Nitoseal SL sits in the trafficked-floor-joint slot of Fosroc’s sealant range. Its natural companion is Nitoprime, the primer that secures adhesion to the concrete joint walls. Where a joint is vertical or needs a gun-applied bead rather than a pour, a gun-grade polyurethane from the same Nitoseal family is the right call instead. On projects where the floor itself needs protection alongside the joints, pair it with a Fosroc Nitoflor floor coating; and where the wider structure needs waterproofing rather than joint sealing, our Fosroc Nitoproof membranes cover that scope. Across other brands we stock, comparable self-levelling PU floor-joint sealants are available from Sika and MC-Bauchemie for specifiers who are tied to those systems.
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