About Fosroc Nitofoam 40

Fosroc Nitofoam 40 belongs to Fosroc’s Nitofoam range of sprayed rigid polyurethane insulation. It is supplied as two liquid components — a polyol side and an isocyanate side — that are heated, metered and combined at the spray gun. On contact the mix reacts and expands, curing within seconds into a rigid, closed-cell foam with a nominal core density in the region of 40 kg/m3. Because it is blown with an HFC agent and is free from CFCs and HCFCs, it avoids the ozone-depleting propellants of older foam chemistries while still delivering the low thermal conductivity that closed-cell polyurethane is known for. The “40” in the name signals the lighter-density grade of the family; the companion Nitofoam 45 grade runs a little denser for jobs that need extra surface hardness or foot traffic tolerance.

The real advantage of a sprayed system over cut boards is continuity. Nitofoam 40 is applied in situ, so it bonds directly to the deck and flows into upstands, around drainage outlets and over irregular profiles as one unbroken skin. That seamlessness removes the butt joints and mechanical fixings where board insulation typically leaks heat and, later, water. On a Space Arc project the foam is never the finished surface — it is the insulating core of a build-up. Once the foam is at thickness it is overcoated with a Fosroc protective system such as Polyurea, a liquid polyurethane membrane or Brushbond Roofguard, which together give the roof its waterproofing, UV resistance and fire performance. Applied by specialist crews, this combination turns an ordinary RCC roof into an insulated, weatherproofed and monolithic assembly in a single mobilisation.

The technical insight

The insulating power of Nitofoam 40 comes from its closed-cell structure. As the two components react they generate gas that is trapped inside millions of sealed cells, and it is this captive gas — not the polymer walls — that does most of the insulating work, because still gas conducts heat far more slowly than the surrounding solid. A closed-cell morphology also means the cells do not interconnect, so the foam resists moisture pick-up and does not wick water through its body the way an open-cell foam would. Spraying the material as a reacting liquid is what lets it self-adhere and self-level: it grips the substrate mechanically and chemically as it rises, then locks that bond in as it cures, which is why a properly sprayed layer behaves as one continuous board with no fasteners and no seams to fail. Building the thickness in thin successive lifts rather than one thick pass keeps the exotherm controlled and the cell structure fine and even, which is what protects the density and the insulation value the specifier is paying for.

Where it is used

• Thermal insulation of flat and low-slope RCC roof slabs on commercial and industrial buildings
• In-situ insulation layer beneath a Fosroc Polyurea or liquid-PU waterproofing overcoat
• Warehouse, factory and cold-process shed roofs where heat gain must be curbed
• Insulating irregular roof profiles, domes and areas congested with drains, pipes and upstands
• Re-roofing and thermal upgrade of existing slabs without stripping back to structure
• Institutional, commercial and residential terraces targeting lower air-conditioning load
• Roofs where a lightweight insulation is preferred over heavy screeds or dead-weight boards
• Base course for combined waterproof-plus-fire-rated roof build-ups using Brushbond Roofguard

Key advantages

• Sprays as one seamless, jointless blanket that eliminates the thermal bridges of board insulation
• Closed-cell structure gives low thermal conductivity and good resistance to moisture pick-up
• Self-adhering and self-levelling — bonds to the deck with no mechanical fixings
• Lightweight, so it adds negligible dead load compared with insulating screeds
• Follows complex geometry, flowing around drains, upstands and penetrations
• HFC-blown and free from CFCs and HCFCs, avoiding ozone-depleting propellants
• Adheres to a wide range of substrates including concrete, brickwork, wood, particle board and sheet metals
• Fast machine application lets large roof areas be insulated in a single mobilisation

Limitations & considerations

• Not a finished or waterproof surface on its own — it must be overcoated to resist UV, weather and traffic
• Bare polyurethane foam degrades under sunlight, so the protective topcoat cannot be deferred
• Requires specialist metered spray equipment and trained applicators; it is not a hand-applied product
• Application is weather-sensitive — the deck must be clean, dry and within the specified ambient range
• Overspray drift means adjacent surfaces, glazing and vehicles need masking on windy days
• Site-mixed reactive chemistry demands correct component temperature and ratio for the rated density and yield

Selection & best practice

Specifications

Industry use cases

How we position Fosroc Nitofoam 40

Nitofoam 40 is best specified as one part of a Fosroc roof system rather than in isolation. Space Arc typically pairs it with a Fosroc overcoat — Polyurea, a liquid polyurethane membrane, or Brushbond Roofguard — to complete the waterproofing and fire performance over the insulating core. Where a denser, harder-wearing foam is called for, the sibling Nitofoam 45 grade is the natural step up. For projects that need joint sealing or expansion-joint filling on the same roof, we can supply Fosroc’s Hydrocell XL joint filler board and Nitoseal or Colpor joint sealants from the same brand family. And where a client’s specification calls for another brand, we also carry comparable thermal-insulation and waterproofing lines from Dr. Fixit and Sika, so the roof build-up can be matched to the tender.

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