About Sika CoolCoat

Sika CoolCoat is Sika’s liquid-applied answer to the two things that punish an Indian roof slab: monsoon water and summer heat. Most sites treat these separately — a waterproofing membrane for the rain, and later a reflective paint or false ceiling for the heat. CoolCoat folds both jobs into a single acrylic system. It is water-based and single-component, so there is no mixing ratio to get wrong on site; the crew primes, then lays two coats by brush or roller. The membrane cures into a seamless, flexible film that bridges hairline and moving cracks up to about 3.2 mm, which is exactly where old rigid screeds and brittle coatings tend to fail first.

What makes it a “cool” coat rather than just a white waterproofer is the pigment and reflectance engineering. The finished surface carries a Solar Reflectance Index of 102 (tested to ASTM E1980), meaning it throws most of the sun’s radiant energy back rather than soaking it into the slab. On a Delhi-NCR terrace that difference shows up as a measurably cooler roof surface, a cooler top-floor room, and less thermal cycling stress on the concrete below. Sika builds in cross-linking polymers for weathering life and an antifungal additive so the white finish resists the algae and black streaking that normally ruin reflective roofs within a couple of monsoons. It bonds directly to concrete, brickwork, asbestos, aged bitumen and metal decks, which is why it gets specified as much for refurbishment as for new work.

The technical insight

The performance comes from combining two physics problems in one film. For water, the acrylic dispersion coalesces into a continuous elastomeric membrane; the glass micro-fibres act like rebar in miniature, holding the film together across substrate movement so it can bridge cracks up to ~3.2 mm instead of tearing at them. For heat, the ruling number is the Solar Reflectance Index. A conventional grey RCC roof has an SRI near 0-20 and absorbs almost everything that hits it; CoolCoat’s high-reflectance white pigmentation pushes SRI to 102 (ASTM E1980), so the bulk of incident solar radiation is reflected and re-emitted rather than conducted down into the slab. Because the film is also vapour-permeable, moisture trapped in the deck can still escape outward instead of blistering the coating — a common failure mode with impermeable membranes over damp concrete. The net effect is a lower roof-surface temperature, reduced heat flow into the building, and less daily expansion-contraction fatigue in the concrete, which indirectly extends the life of the waterproofing itself.

Where it is used

• Cool-roof waterproofing on exposed RCC roof slabs and flat or sloped terraces
• Refurbishment overcoat on aged bituminous membranes and asbestos-cement roofs
• Heat-reflective, waterproof finish on sunshades, chajjas and balconies
• Protective reflective coating on external walls to reduce facade heat gain
• Exterior coating on PVC and plastic overhead water tanks to cut heat pickup
• Top-floor and terrace treatment on offices, showrooms and residences to lower cooling load
• Clay-tile and lime-terrace roofs needing a flexible waterproof skin
• Localised crack and joint reinforcement using Sika Fab1 fabric embedded in the coat

Key advantages

• One system does two jobs — waterproofing plus solar reflectance (SRI 102, ASTM E1980) — removing a separate heat-treatment layer
• Single-component and water-based: no site mixing, low odour, easy brush or roller application
• Micro-fibre reinforcement gives genuine crack-bridging up to ~3.2 mm over moving substrates
• Vapour-permeable film lets the deck breathe, reducing blistering over damp concrete
• Antifungal additive keeps the white reflective surface from streaking with algae in the monsoon
• Bonds to concrete, brick, asbestos, aged bitumen and metal without specialist priming systems
• Seamless liquid membrane with no laps or joints, so no weak seams to fail
• Suits both new construction and refurbishment, making it flexible for consultants and applicators

Limitations & considerations

• It is a coating, not a structural repair — active leaks, ponding and honeycombed concrete must be fixed and the deck made sound before application
• Reflectance depends on cleanliness; dust, foot traffic and pollution will dull the white finish over time and periodically need washing to hold SRI
• Being acrylic and water-based, it must not be applied in rain or when rain is imminent within the cure window, which constrains monsoon scheduling
• Application is limited to a moderate ambient window (roughly +10°C to +45°C); extreme heat or cold on the slab affects film formation
• Not intended for permanently immersed conditions such as water-tank interiors or basements — it is an exposed-surface membrane
• Two full coats at the stated consumption are needed for the rated crack-bridging and reflectance; under-application quietly loses performance

Selection & best practice

Specifications

Industry use cases

How we position Sika CoolCoat

Within Sika’s own range, CoolCoat sits alongside the Sikalastic cool-roof family (such as Sikalastic-510 CoolCoat and the fibre-reinforced Sikalastic-520 Cool Coat Fibers) — step up to those where a higher-performance or thicker liquid membrane is called for, and pair the coat with Sika CoolCoat Primer and Sika Fab1 reinforcing fabric as part of the same system. For terrace and wet-area waterproofing where heat reflection is not the goal, Sika’s SikaTop and Sikalastic membrane products are the natural alternatives. From our other brands we can offer Dr. Fixit and STP heat-reflective and acrylic terrace coatings where budget or availability drives the choice. If your priority is protecting the structural concrete rather than cooling the roof, look at the Fosroc Dekguard range we also carry.

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