Sika Sikalastic-520 Cool Coat Fibers IN
A fibre-reinforced, water-based acrylic membrane that waterproofs the roof and reflects solar heat in one cold-applied, seamless coat.
What is it?
A single-component, water-based acrylic liquid-applied membrane reinforced with glass micro-fibres, combining crack-bridging waterproofing with a high-SRI heat-reflective finish.
Where is it used?
Exposed flat and sloping roofs, industrial sheds, external walls and sunshades, and refurbishment of aged concrete, tile, asbestos or bitumen roofs.
Why use it?
It seals the roof against water while its white reflective surface lowers membrane and interior temperatures, cutting heat ingress and improving thermal comfort.
How is it applied?
Brush or roller, cold-applied straight from the container over a primed, sound, dry substrate in two coats; larger or high-movement areas take Sika Fabric-50 reinforcement.
About Sika Sikalastic-520 Cool Coat Fibers IN
Sikalastic-520 Cool Coat Fibers IN is Sika’s answer to a problem every Indian roof faces: it has to stay watertight through the monsoon and stay cool through the summer. Rather than treating those as two separate jobs, this single-component acrylic membrane does both. It is a water-based, cold-applied liquid that goes down by brush or roller directly from the container, curing into a seamless elastic film with no joints, laps or naked flames on site. The membrane is reinforced with special glass micro-fibres, carries cross-linking polymers for toughness, and includes an advanced antifungal additive so the white surface resists the algae and fungal staining that plague coatings in humid climates.
For engineers and contractors, the appeal is the combination. On one hand it is a genuine waterproofing membrane with meaningful crack-bridging, so it accommodates the fine thermal cracking that opens up on exposed slabs and sheds. On the other, its high Solar Reflectance Index means the coated surface bounces back a large share of incident solar radiation instead of absorbing it, so the roof runs cooler and less of that heat migrates indoors. The result is a lighter cooling load and a more comfortable building beneath, delivered by a coating that bonds to concrete, masonry, tiles, asbestos, bitumen and metal decks alike.
The technical insight
The membrane works on two physical principles at once. First, waterproofing: the acrylic dries to a continuous, elastic film reinforced with glass micro-fibres. Those fibres and the cross-linking polymers give the film enough tensile strength and elongation to stretch over hairline movement rather than tearing, so shrinkage cracks and thermal cracks in the substrate stay bridged instead of telegraphing through and letting water in. Second, heat rejection: the pigmented white finish carries a high Solar Reflectance Index (SRI 112 measured to ASTM E1980), which is a combined measure of how much sunlight the surface reflects and how efficiently it re-emits absorbed heat. A high SRI keeps the membrane’s own surface temperature down, and because the roof slab underneath never gets as hot, far less heat conducts into the rooms below. In effect the coating attacks the two ways a flat roof fails an occupant in India, water getting in and heat building up, with a single film.
Where it is used
- Heat-reflective waterproofing of exposed flat and sloping RCC roofs
- Crack-resistant reflective coatings on industrial and warehouse shed roofs
- Waterproofing of external walls, parapets and sunshades (chajjas)
- Refurbishment of ageing concrete, tile, asbestos-cement and bitumen roofs
- Exterior coating of PVC overhead and terrace water tanks
- Cool-roof upgrades on commercial and institutional buildings to reduce cooling load
- Reflective protection over sound existing waterproofing that has lost its finish
- High-movement or large roof areas when reinforced with Sika Fabric-50
Key advantages
- Waterproofs and reflects heat in one product, removing the need for a separate reflective topcoat
- Cold-applied by brush or roller with no torching, mixing or specialist plant
- Glass micro-fibre reinforcement gives real crack-bridging over fine substrate movement
- High Solar Reflectance Index (112 to ASTM E1980) lowers surface and interior temperatures
- Built-in antifungal additive resists algae and fungal staining on the white finish
- Seamless, jointless finish that conforms around upstands, drains and details
- Bonds to a wide range of substrates including concrete, tiles, asbestos, bitumen and metal
- Water-based and low-odour, suitable for occupied buildings
Limitations & considerations
- Not intended for permanent water immersion or areas subject to standing water (ponding)
- The fresh film must be protected from rain, condensation and dampness for at least 24 hours after application
- Full cure before any ponding test takes around 7 days, which the programme must allow for
- Performance depends on correct priming and a sound, dry substrate below 6% moisture
- It is a coating, not a structural repair, so cracks and defects must be treated before application
- Reflective and antifungal benefit depends on keeping the white surface reasonably clean over time
Selection & best practice
Start with a sound, clean and dry substrate: remove laitance, dust, oil and any loose material, and rake out and treat live cracks and defects before coating. Confirm substrate moisture is not above 6% and apply within the recommended window of +10C to +45C with relative humidity up to 80%. Prime the surface first at the stated rate to lock down dust and improve adhesion. Apply the membrane in at least two coats by brush or roller, laying the second coat at right angles to the first for even build, and reinforce larger or high-movement areas and details with Sika Fabric-50 embedded between coats. Protect the fresh coating from rain, dew and foot traffic for the first 24 hours, and do not subject the finished membrane to ponding or a water test before it has cured for 7 days. Plan the work so the reflective white finish is applied late in the programme to keep it clean.
Specifications
| Type | Single-component, water-based acrylic, fibre-reinforced liquid membrane |
| Solar Reflectance Index (SRI) | 112 (ASTM E1980) |
| Consumption – roof waterproofing | ~0.75 kg/m² per coat |
| Consumption – reflective wall coating | ~0.35 kg/m² per coat |
| Primer consumption | 0.2–0.3 kg/m² per coat |
| Colours | White or grey |
| Pack size | 10 kg container |
| Application temperature | +10°C to +45°C (air and substrate) |
| Ponding / full cure | Do not pond before 7 days; protect from water for first 24 hours |
Industry use cases
Industrial & Warehousing
Reflective, crack-resistant coating over large exposed shed roofs to cut internal heat build-up and stop leaks without shutting the facility down.
Commercial & Retail
Cool-roof upgrade on office and mall terraces that lowers the air-conditioning load while re-waterproofing the slab in one seamless system.
Residential & Housing
Terrace and chajja waterproofing on RCC homes and apartment blocks, with a white reflective finish that keeps top-floor rooms noticeably cooler.
Institutional & Public
Refurbishment of ageing school, hospital and government-building roofs, including tile, asbestos and bitumen surfaces, with a low-odour water-based coat.
Frequently asked questions
Is Sikalastic-520 Cool Coat Fibers a waterproofing membrane or just a reflective paint?
How much material do I need per square metre?
Which surfaces can it be applied to?
How long before it can take rain or a ponding test?
Can it handle roof movement and cracking?
Does the white finish stay clean, and does it really keep the building cooler?
How we position Sika Sikalastic-520 Cool Coat Fibers IN
Within the Sika range, Sikalastic-520 Cool Coat Fibers IN sits as the fibre-reinforced, crack-bridging upgrade over the plainer Sika CoolCoat and Sikalastic-510 CoolCoat IN reflective coatings; specify the 520 where the roof needs genuine waterproofing and movement tolerance rather than reflectivity alone, and pair it with Sika Fabric-50 on large or high-movement areas. Where a project standardises on Fosroc, our closest equivalent from that range is Brushbond Roofguard Premium, an acrylic solar-reflective elastomeric coating that likewise waterproofs and cools in one system. For pure waterproofing without the cool-roof requirement, look at Fosroc Brushbond fibre-reinforced renders or Dr. Fixit acrylic membranes from our other brand lines.
Fosroc Brushbond Roofguard Premium — Choose the Fosroc option when the project is standardised on the Fosroc system or wants an acrylic-modified elastomeric coating with a slightly heavier elastomeric build for solar-reflective waterproofing.
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