STP ShaliCem EWP
A two-component acrylic polymer-modified cementitious coating that cures to a flexible, seamless elastomeric skin, bridges shrinkage cracks up to 1.5 mm, and is certified safe for potable-water contact.
What is it?
A two-part, UV-resistant, acrylic polymer-modified cementitious coating. A grey powder (Component A) is mixed on site with a milky-white liquid polymer (Component B) to form a flexible, elastomeric waterproofing slurry.
Where is it used?
Roofs and terraces, basement rafts and retaining walls, water-retaining structures, and behind tile beds in kitchens and toilets, on both concrete and masonry.
Why use it?
It combines the durability of cement with the flexibility of acrylic polymer, so it bridges hairline movement, breathes to release vapour, and stays safe for drinking-water tanks.
How is it applied?
Mixed A:B at 14.8:5.2 by weight into a lump-free slurry, then brush, roller, trowel or spray-applied in two coats onto a saturated-surface-dry substrate to a 1 mm dry film.
About STP ShaliCem EWP
STP ShaliCem EWP sits in the middle of the cementitious-waterproofing family: heavier and more robust than a thin acrylic paint, yet far more forgiving than a rigid, plain-cement slurry. Component A carries the cement and graded fillers; Component B is the acrylic polymer that does the flexing. Once the two are combined on site and the coating cures, you get a seamless, monolithic film that grips the substrate and moves with it rather than cracking off. For the Indian site engineer, its most useful property is honest tolerance of everyday concrete behaviour — the coating stretches around the hairline shrinkage cracks that appear in almost every slab and screed instead of telegraphing them straight through.
What makes it a practical specification for potable and semi-potable structures is the certification behind it. ShaliCem EWP is approved under DIN 1048 for water penetration, tested to BS 1881 Part 5, and cleared to USFDA 175.300 for contact with potable water, which is why it is a defensible choice for overhead tanks, underground sumps and swimming pools where a lot of cheaper coatings simply cannot be used. It is also UV-resistant and breathable, so an exposed terrace treated with it will not blister from trapped vapour or chalk away in a season. Space Arc supplies it as a distributor and applicator across Delhi NCR and pan-India, so specifiers can source the genuine STP material and the trained crews to lay it correctly.
The technical insight
The performance comes from a polymer-cement composite. As the slurry sets, the cement fraction hydrates into a hard, mineral matrix while the acrylic polymer coalesces into a continuous elastic film woven through it. That dual structure is why the coating reads roughly 80% elongation at 7 days yet still develops around 2 MPa adhesion to concrete: the cement anchors it and resists water pressure, and the polymer supplies the stretch that lets it span movement. The rated crack-bridging of up to 1.5 mm is a direct consequence — the elastic phase keeps the film intact over a moving hairline where a brittle mineral coating would simply tear. Being breathable, the film lets water vapour escape from the substrate while blocking liquid water and dissolved salts, so moisture driven from inside the structure is not trapped under the membrane to lift it off. The chemistry is the reason the two components must never be diluted with water on site: added water dilutes the polymer, and the elastic phase you are paying for is exactly what you lose.
Where it is used
- Roof slabs and terraces, including exposed areas thanks to its UV resistance
- Basement rafts and retaining walls treated against rising dampness and ground water
- Overhead and underground water tanks, sumps and reservoirs (potable-water certified)
- Swimming pools, water features and other permanently wet water-retaining structures
- Damp patches and construction joints on walls where water ingress is likely
- Waterproofing under tile-bed mortar in kitchens, toilets, balconies and wet areas
- Both concrete and masonry substrates as a general positive-side coating
- As a reinforced system with embedded glass fabric over cracked or high-movement areas
Key advantages
- Flexible elastomeric film bridges shrinkage and hairline cracks up to 1.5 mm (ASTM C836)
- Certified safe for potable-water contact (USFDA 175.300) for drinking-water tanks and pools
- High elongation of about 80% at 7 days with strong 2 MPa adhesion to concrete
- UV-resistant, so it can be left exposed on terraces without a mandatory protective screed
- Breathable and water-vapour permeable, preventing trapped moisture from blistering the film
- Bonds to both porous and non-porous surfaces and applies by brush, roller, trowel or spray
- Non-toxic and solvent-free, safe to use in enclosed tanks, sumps and confined wet areas
- Ready-to-use two-pack with no site batching of aggregates or admixtures required
Limitations & considerations
- Positive-side coating; it is not intended as a standalone negative-side or under-hydrostatic-pressure barrier
- Must never be diluted with water during mixing — added water destroys the elastic polymer phase
- Site-mixed with a 45-60 minute working time, so only mix what a crew can lay within the pot life
- Needs a saturated-surface-dry substrate with no standing water; over-wet or bone-dry surfaces cause failure
- Not a wearing surface — it must be protected under traffic (e.g. PCC screed or ShaliProtek PU HA) and can be punctured by dragged rebar
- Requires disciplined moist curing for 2-3 days plus air-drying before submersion, which extends the programme
Selection & best practice
Success depends almost entirely on substrate discipline. Clean the surface back to a sound profile by grinding, water-blasting or acid-washing, and make good honeycombs, holes and live cracks with a PMC mortar or ShaliFix FRM before you start. Pre-wet dense concrete at least twice, thirty minutes apart, so the slab reaches a saturated-surface-dry state with a matt-damp look but no puddles. Mix by adding the full Component A slowly into the whole of Component B under a slow paddle (300-400 rpm) until lump-free, then let it stand four to five minutes to release air. Always lay two coats to a 1 mm total dry film, applying the second only once the first has dried, and reinforce high-movement zones or junctions with embedded glass fabric. Keep substrate and ambient temperature between +10 C and +40 C, air-dry three to six hours with no curing water, then fog-cure for two to three days and allow three days of air-drying before any water is impounded.
Specifications
| Product type | Two-component, UV-resistant, acrylic polymer-modified cementitious elastomeric coating |
| Mixing ratio (A:B) | 14.8 : 5.2 by weight (37 : 13 w/w) |
| Mixed density | 1.80 ± 0.03 g/cc (ASTM D 1475) |
| Crack-bridging ability | Up to 1.5 mm (ASTM C 836) |
| Elongation (7 days) | 80 ± 10% (ASTM D 412) |
| Tensile strength (7 days) | 2 ± 0.2 MPa (ASTM D 412) |
| Adhesion to concrete | 2 ± 0.5 MPa (ASTM D 4541) |
| Working time / recoat / full cure | 45-60 min; recoat 8-12 hr; full cure 7 days |
| DFT & coverage | 1 mm in 2 coats; approx. 1.6-1.8 kg/m² per mm |
| Packaging & shelf life | 20 kg & 50 kg packs; 12 months at 5-40°C |
| Standards / approvals | DIN 1048, BS 1881 Part 5, USFDA 175.300 (potable water) |
Industry use cases
Water & Sanitation
Lining of overhead tanks, underground sumps and reservoirs where the USFDA 175.300 potable-water clearance makes it a compliant, non-toxic choice.
Residential & Housing
Waterproofing of terraces, sunken toilets and kitchen wet areas under tile beds, where its flexibility handles slab shrinkage cracking.
Commercial & Institutional
Basement rafts, retaining walls and lift pits in offices, malls and hospitals treated against rising dampness and ground moisture.
Hospitality & Recreation
Swimming pools, water bodies and landscape features that stay permanently wet and demand a flexible, crack-tolerant coating.
Infrastructure
Exposed roof slabs and water-retaining civil structures where UV resistance allows the coating to be left uncovered.
Frequently asked questions
Is ShaliCem EWP safe for drinking-water tanks?
How much ShaliCem EWP do I need per square metre?
Can it be left exposed on a roof, or must it be covered?
What is the mixing ratio and can I add water to make it workable?
How is it different from a plain cement waterproofing slurry?
What surface preparation and curing does it need?
How we position STP ShaliCem EWP
Within STP’s own range, step up to ShaliCem EWP 150 when a project needs a higher-performance grade of the same chemistry, and pair the system with ShaliFix FRM for repairing cracks and honeycombs beforehand, ShaliPlast IW as an integral waterproofer in the protective screed, and ShaliProtek PU HA where the treated roof must take foot traffic. Against our other brands, ShaliCem EWP competes directly with Fosroc Nitocote CM210 and Fosroc Brushbond in the flexible-cementitious category, and with Dr. Fixit Roofseal or Pidilite’s cementitious coatings for terrace and wet-area work; the right pick usually comes down to the approvals a consultant has already specified and local availability, both of which Space Arc can advise on.
Fosroc Nitocote CM210 — A specifier already standardised on Fosroc, or one who wants an elastomeric cementitious coating backed by Fosroc’s approvals and site-support network, may prefer Nitocote CM210 as the directly equivalent two-part flexible option.
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