STP ShaliCem FWP
A two-component, polymer-modified cementitious waterproof coating from STP that bonds to damp masonry and seals it from either face, with potable-water clearance for tanks and reservoirs.
What is it?
A two-pack (powder plus liquid polymer) cementitious waterproofing coating that brushes, rolls or sprays on to form a bonded, breathable seal over concrete and masonry.
Where is it used?
Basements, tunnels, machinery pits, water tanks, reservoirs, roofs, terraces, swimming pools and toilets, including both positive and negative side treatment.
Why use it?
It sticks directly to sound damp substrates without a primer, carries USFDA clearance for potable-water contact, and resists chloride and carbonation ingress.
How is it applied?
Mix Component A into B at 4:1 by weight to a lump-free slurry, then apply two coats by brush, roller, trowel or spray, air dry, and moist-cure before wetting.
About STP ShaliCem FWP
STP ShaliCem FWP sits in the everyday, work-horse end of cementitious waterproofing. It arrives as a matched set: a grey Portland-based powder (Component A) and a milky-white acrylic polymer liquid (Component B) that you blend on site at a fixed 4:1 ratio by weight. No water is added and no primer is needed. Once mixed to a smooth slurry and left to breathe for a few minutes, it is brushed, rolled, trowelled or spray-applied straight onto a saturated-surface-dry substrate. As it cures it chemically bonds into the concrete pores rather than merely sitting on top, giving a monolithic seal that will not peel back at the edges the way an unbonded sheet can.
For an Indian engineer or contractor, the appeal is practical rather than exotic. The coating tolerates the damp, imperfect surfaces found on real sites, works on both the water-facing (positive) and dry (negative) side of a wall, and holds USFDA-175.300 clearance for potable-water contact, so it is at home lining an overhead tank or an underground reservoir. It is a flexible film with modest crack accommodation, not a heavy-duty elastomeric membrane; used within that envelope it is a dependable, cost-effective choice for the large volume of tanks, basements, wet areas and terraces that make up most waterproofing scopes.
The technical insight
The performance comes from marrying two chemistries. The powder contributes the hydraulic strength of cement, gaining roughly 20-25 MPa in compression at 28 days, which is why the cured film resists foot traffic and hydrostatic load rather than staying soft. The acrylic polymer in Component B fills the space between cement grains as it dries, blocking the capillary network that lets water, chlorides and CO2 migrate through ordinary render. That same polymer gives the film its 10-12% elongation at 14 days, enough to ride over hairline shrinkage cracks and the small daily movements of a concrete deck without splitting, while an adhesion of around 2 MPa to concrete keeps it locked in place under both positive and negative water pressure. Because the mix reaches a mixed density near 2.0 g/cc and needs no dilution water, the applied slurry stays dense and pinhole-free, so the barrier depends on film integrity rather than sheer thickness.
Where it is used
- Positive and negative side waterproofing of internal and external masonry walls
- Basements, lift pits, tunnels and machinery pits below the water table
- Underground and overhead water tanks, cisterns and reservoirs
- Potable-water storage structures requiring a non-tainting lining
- Roofs and terraces ahead of screed and protective finishes
- Swimming pools, sunk toilets and other wet areas
- Sealing coat over honeycombed or patch-repaired concrete faces
- Protective coat guarding RCC against chloride and carbonation attack
Key advantages
- Bonds directly to sound damp substrates with no separate primer coat
- USFDA-175.300 cleared for contact with potable water
- Works from both the positive and negative face of a structure
- Blocks water penetration plus chloride and carbonation ingress
- Ready to mix with the supplied polymer, no site water added
- Applied by brush, roller, trowel or spray to suit the surface
- UV resistant, so it tolerates exposure during construction
- Gains real compressive strength, 20-25 MPa at 28 days
Limitations & considerations
- Flexibility is modest at 10-12% elongation; not for wide or live structural cracks
- Rigid cracks and honeycombing must be pre-repaired with a mortar such as ShaliFix FRM
- Needs disciplined moist curing for 2-3 days, and hot windy weather makes this critical
- The coating must never be left permanently bone-dry or fully submerged long term without a protective layer
- Exposed trafficable roofs need a wearing coat such as a PU topcoat over it
- Adding water to thin the mix, or dragging rebar over the film, will compromise it
Selection & best practice
Get the substrate right first: scarify or grind off laitance and contamination, cut out honeycombing and cracks and make them good with a polymer-modified mortar, then pre-wet the surface to a saturated-surface-dry condition with no standing water. Pour the whole of Component B into a clean drum, add Component A slowly while paddle-mixing at 300-400 rpm to a lump-free slurry, and let it stand 4-5 minutes to release air. Apply in two coats, each no thicker than about 1 mm, letting the first dry before the second and keeping total coverage near 1.6-1.8 kg/m2. Air dry the finished coating for 3-6 hours with no curing water, protecting it from rain or hot wind, then fog-spray to keep it damp for 2-3 days. Allow a further 3 days of air drying before flooding a tank, and top with a protective screed or PU coat where the surface will be trafficked.
Specifications
| Product type | 2K polymer-modified cementitious waterproof coating |
| Mixing ratio (A:B by weight) | 4 : 1 |
| Theoretical coverage | 1.6-1.8 kg/m2 in 2 coats |
| Working time | 50-70 minutes at 27C |
| Elongation at 14 days (ASTM D2370) | 10-12% |
| Adhesion to concrete (ASTM D4541) | 2 +/- 0.3 MPa |
| Compressive strength at 28 days (ASTM C109) | 20-25 MPa |
| Potable-water approval | USFDA-175.300 |
| Packaging | 25 kg unit: 20 kg powder + 5 kg liquid |
Industry use cases
Water utilities & MEP
Lining overhead tanks, underground sumps and reservoirs where the USFDA-175.300 potable clearance and both-side sealing matter most.
Residential & commercial buildings
Sunk toilets, balconies, terraces and basement retaining walls, sealed before screed and tiling on damp concrete without a primer.
Infrastructure & below-grade
Tunnels, lift pits and machinery pits taking negative-side water pressure, where a bonded coating resists ingress a sheet cannot.
Recreation & pools
Swimming pool shells and water features waterproofed and cured, then air dried before filling per the recommended schedule.
RCC durability protection
A protective barrier coat on exposed reinforced concrete to slow chloride and carbonation attack in coastal and industrial settings.
Frequently asked questions
Can ShaliCem FWP be used inside drinking-water tanks?
Does it work on the negative (inner dry) side of a wall?
How much material do I need per square metre?
Will it bridge cracks in my slab?
Do I need a primer or extra water when mixing?
Can it be left exposed on a trafficable roof?
How we position STP ShaliCem FWP
ShaliCem FWP is STP’s value flexible cementitious coat and pairs naturally with the rest of the ShaliCem range: step up to ShaliCem EWP, EWP 150 or EWP 200 when you need higher elongation and a UV-stable elastomeric finish for exposed terraces, or ShaliCem EWP AR where anti-root protection is required over planters and podiums. On the same job, prepare the substrate with STP ShaliFix FRM for crack and honeycomb repair, dose fresh concrete or screeds with ShaliPlast IW integral waterproofer, and protect trafficable areas with ShaliProtek PU HA. Where a specification calls for higher crack-bridging and hydrostatic resistance, we also supply the Fosroc equivalent, Nitocote CM210, and can cross-refer against Dr. Fixit and MC-Bauchemie cementitious systems to match approved-brand lists.
Fosroc Nitocote CM210 — Specify the Fosroc option when the job needs higher crack-bridging (up to about 0.5 mm) and rated resistance to positive and negative hydrostatic pressure beyond what a value cementitious coat offers.
Related Waterproofing products
Source STP ShaliCem FWP for your project
Authorised distribution, technical advice & professional application across Delhi NCR and Pan-India.