STP ShaliCryl LM HI
A single-component, microsphere-reinforced acrylic liquid membrane that waterproofs and cools exposed roofs in one seamless coat.
What is it?
A single-component, water-based acrylic liquid membrane reinforced with hollow glass microspheres. It cures into a seamless, elastic film that both waterproofs and reflects solar heat.
Where is it used?
Exposed terraces, sloped and inclined roofs, corrugated sheet roofs, chajjas, balconies, parapets, and complex geometry like domes and arches.
Why use it?
It combines waterproofing with a high Solar Reflectivity Index of 113, so it keeps interiors cooler while bridging shrinkage cracks and resisting UV and monsoon exposure.
How is it applied?
Brush, roller or squeegee over a diluted primer coat, then two full coats at 0.75 kg per square metre each to build a 1 mm dry film.
About STP ShaliCryl LM HI
STP ShaliCryl LM HI is the high-performance grade in STP Limited’s acrylic waterproofing family, engineered for roofs that stay fully exposed to the sun. Unlike a plain acrylic coating, it is loaded with hollow glass microspheres and built on ceramic micro-technology, so the cured film does two jobs at once: it seals the surface against water and reflects the bulk of incident solar radiation back to the sky. That reflective action is measured by a Solar Reflectivity Index of 113, which is why the product is marketed as an energy-saving, heat-insulative membrane rather than a simple waterproofer. For Indian rooftops that bake through summer and then take a monsoon battering, that dual behaviour is genuinely useful.
The technical insight
The membrane works on two physical mechanisms that share the same coat. First, the acrylic polymer cures into a continuous, elastomeric film with roughly 200 percent elongation, so it stretches over hairline shrinkage cracks and moves with the slab instead of tearing. Second, the hollow glass microspheres dispersed through that film scatter and reflect solar energy at the surface, while the microsphere-filled matrix has a low thermal conductivity of about 0.09 W/mK. The result is a barrier that reflects most of the sun’s radiation before it is absorbed and resists the little that gets through from conducting into the slab below. Because the film is monolithic and joint-free, there are no laps or seams where water can track under the membrane, which is the usual failure point of sheet systems on irregular roofs.
Where it is used
- Waterproofing and heat-reflective coating for exposed RCC terraces and roof slabs
- Sloped, inclined and corrugated sheet roofs where sheet membranes are hard to lap
- Chajjas, sunshades, balconies and parapet walls
- Complex geometry such as domes, arches, paraboloids and flashing upstands
- Recoating over existing cementitious treatments like brick-bat coba, screeds and old acrylic coatings
- Crack repair and sealing on cementitious surfaces
- Vertical wall waterproofing on the weather-facing side
- Reflective ‘cool roof’ upgrades on buildings targeting lower interior temperatures
Key advantages
- High Solar Reflectivity Index of 113 lowers roof surface temperature and cuts heat gain into the building
- Seamless, monolithic film with no laps or joints to fail on irregular roofs
- High elongation (about 200 percent) bridges shrinkage and hairline cracks
- Strong wet adhesion to both concrete and metal substrates
- UV resistant and weather durable for permanently exposed decks
- Water-based, low-odour and user-friendly, with tools cleaned in plain water
- Tolerates normal foot traffic without a separate protective coat
- Abrasion and dirt-pickup resistant, and washable to maintain reflectivity
Limitations & considerations
- Water-based chemistry means it cannot be applied in the rain or onto damp substrates, so weather windows matter
- Application is restricted to substrate and ambient temperatures between +10 and +40 degrees C
- Existing bitumen-based treatments must be fully removed by mechanical scarification before coating
- It is a coating, not a heavy-duty trafficable deck system; areas with vehicular or heavy point loads need a screed or a PU deck coat
- Reflectivity depends on the surface staying reasonably clean, so a dirty or ponding roof loses some cooling benefit
- Correct film build depends on hitting the specified consumption per coat; under-application reduces both waterproofing and reflective performance
Selection & best practice
Success is mostly about surface prep and film build. Start on a sound, fully dry substrate that has been high-pressure cleaned and freed of dust, grease and loose material; repair hollow patches with ShaliFix FRM and fill cracks with PlastiSeal (or PlastiSeal P for wider cracks) before coating. Prime with ShaliCryl LM HI diluted 1:1 with clean water at 0.2 to 0.3 kg per square metre and let it dry. Then apply two full coats at 0.75 kg per square metre each, allowing the first to dry before the second, to reach a 1 mm dry film; on vertical surfaces apply about 0.34 kg per square metre in two coats for 300-plus microns. Coat all corners, drains, protrusions and upstands with extra passes, and never apply if rain is expected before the film has cured. For extra dirt and water repellency and a cleaner finish, top with a thin glossy coat of ShaliKote LM HI at 0.06 to 0.08 kg per square metre.
Specifications
| Form and colour | White thick liquid |
| Solid content | 65 ± 1% |
| Density | 1.35 ± 0.03 g/cc |
| Solar Reflectivity Index (EN 673 / EN 410) | 113 |
| Elongation at break | 200 ± 20% |
| Tensile strength | 1.8 ± 0.2 N/mm² |
| Thermal conductivity | 0.09 W/mK |
| Hardness | 80–85 Shore A |
| Theoretical coverage | 1.5 kg/m² for 1 mm DFT |
Industry use cases
Residential rooftops
Exposed terraces and sloped roofs on homes and apartments where owners want both a leak-free roof and cooler top-floor rooms through summer.
Commercial and institutional buildings
Large flat and inclined roofs on offices, schools and hospitals targeting lower interior temperatures and reduced air-conditioning load.
Industrial sheds
Corrugated and metal sheet roofs where a seamless liquid membrane is easier to detail than lapped sheets and the reflective coat cuts shopfloor heat.
Re-waterproofing old roofs
Overcoating tired brick-bat coba, screeds and aged acrylic treatments to restore waterproofing and add reflectivity without a full tear-off.
Complex roof geometry
Domes, arches, chajjas and parapet upstands where liquid application reaches details that rigid sheet systems cannot follow cleanly.
Frequently asked questions
What is the coverage of ShaliCryl LM HI?
How is ShaliCryl LM HI different from standard ShaliCryl LM?
Does it really keep the building cooler?
Can it take foot traffic?
What pack sizes and shelf life does it come in?
What surface preparation does it need?
How we position STP ShaliCryl LM HI
ShaliCryl LM HI sits at the top of STP’s acrylic cool-roof range and is best specified as the reflective, UV-durable membrane for permanently exposed roofs. Within the same STP family, pair it with ShaliCryl LM as the base system where a three-coat colour build-up is wanted, ShaliKote LM HI as a glossy dirt- and water-repellent top coat, and STP’s repair materials — ShaliFix FRM for hollow patches and PlastiSeal or PlastiSeal P for crack filling — during preparation. Where the requirement shifts from a reflective cool-roof coating to a heavier trafficked deck, look at a polyurethane system instead of an acrylic. Space Arc also supplies Fosroc for teams standardised on that brand, so a Fosroc-specified project chasing an exposed, UV-stable liquid membrane on decks would map to Fosroc’s Nitoproof range rather than an acrylic coat.
Fosroc Nitoproof 800 — Choose the Fosroc option when the roof or deck needs a heavier-duty, UV-stable liquid membrane rated for light traffic rather than an acrylic cool-roof coating; note it is a polyurethane system without ShaliCryl LM HI’s high solar reflectivity.
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