Sika SikaTop 66
A two-component, polymer-modified cementitious membrane that flexes with the structure, bridges hairline cracks and seals roofs, decks and wet areas without a torch or a primer.
What is it?
A two-part waterproof coating: a modified cement powder gauged with a polymer liquid to form a flexible, breathable membrane that bonds directly to concrete and masonry.
Where is it used?
Flat roof terraces, podium and balcony decks, bathrooms and other wet areas, swimming pool shells, and the internal faces of retaining walls and planter boxes.
Why use it?
It stays elastic after curing, so it accommodates thermal movement and fine cracking that a rigid slurry would telegraph and eventually leak through.
How is it applied?
Mix the two components to a lump-free slurry and apply by brush or roller in two to three coats, building 1.5 to 2.5 mm of dry film at 2.5 to 3.5 kg/m2.
About Sika SikaTop 66
Sika SikaTop 66 belongs to the flexible cementitious waterproofing family that has become the default choice on Indian roofs and wet areas where the substrate is expected to move. It arrives as two matched components: a graded cementitious powder (Component A) and a polymer or latex liquid (Component B). Blended on site in the correct ratio, they cure into a seamless membrane that is bonded to the concrete rather than laid loose over it, so there are no laps, no seams and no torching. Because the film is polymer-modified, it does not behave like a brittle cement slurry; it stretches, recovers and stays keyed to the deck through daily heating and cooling cycles.
For engineers and applicators, the appeal is that a single product handles both horizontal and vertical work with the same technique. It grips a green-cured screed, turns up cleanly at parapets and skirtings, and accepts screed, tiling or protective topping over it once cured. Space Arc Engineering supplies SikaTop 66 as an authorised Sika distributor and applicator across Delhi NCR and Pan-India, so specifiers get genuine batched material backed by on-site guidance on substrate preparation, coverage and detailing at the junctions where most roofs actually fail.
The technical insight
The performance comes from the polymer film that forms between and around the hydrating cement grains. Ordinary cement waterproofing is watertight but rigid, so the moment the slab flexes or a shrinkage crack opens, the coating cracks with it and water finds the path. In SikaTop 66 the polymer knits the matrix together and gives the cured film an elongation at break above 80 percent, which lets it stretch across a moving crack instead of splitting over it. In practice the membrane bridges roughly 0.3 to 0.5 mm of dynamic crack width, the range that thermal cycling and drying shrinkage typically produce on a well-built deck. Two properties then work together: the film blocks liquid water while remaining vapour-permeable, so any moisture already in the slab can escape rather than build vapour pressure and blister the coating. The result is a bonded, elastic skin that moves with the structure and keeps sealing where a hard coating would have already failed.
Where it is used
- Waterproofing exposed concrete flat roof and terrace slabs before screed or tiling
- Podium decks and landscaped deck areas over occupied space
- Balcony and chajja floors where thermal movement and ponding are common
- Bathroom, toilet and other wet-area floors and walls prior to tile fixing
- Swimming pool shells and internal water-retaining surfaces
- Internal faces of retaining walls, sunken slabs and planter boxes
- Overhead and vertical surfaces such as parapets, skirtings and upstands
- Protective coating over sound concrete exposed to weathering and moisture
Key advantages
- Stays flexible after curing, bridging fine cracks up to about 0.3 to 0.5 mm rather than splitting over them
- Elongation at break above 80 percent accommodates daily thermal and shrinkage movement
- Bonds directly to concrete and masonry, so no separate primer is needed in normal conditions
- Breathable film lets slab moisture escape, reducing the risk of blistering and delamination
- Seamless brush or roller application with no laps, torching or hot works on site
- One product serves both horizontal and vertical surfaces, simplifying detailing at junctions
- Can be overcoated with screed, tiles or a protective topping once cured
- Two-component pre-batched supply keeps the polymer-to-powder ratio consistent on site
Limitations & considerations
- It is a thin bonded membrane, not a structural crack repair; live or moving cracks beyond its bridging range must be treated separately first
- Bridging capacity is limited to roughly 0.3 to 0.5 mm, so it is not a substitute for an expansion-joint system
- Needs a sound, clean, laitance-free and firmly damp substrate; it will not hold over dust, oil or unstable screed
- Being cementitious, it requires proper moist curing and protection from rain and direct sun until it has set
- It must be protected under traffic or ponding; it is not designed as a bare wearing surface for foot or vehicle traffic
- Correct film thickness depends on achieving the full application rate over the specified number of coats, not on a single heavy pass
Selection & best practice
Prepare the substrate first: it should be structurally sound, clean and free of laitance, curing compound, oil and loose material, then pre-wetted to a saturated surface-dry condition without standing water. Rake out and fill any honeycombing, and form coving at wall-to-floor junctions so the membrane can turn up without a sharp corner. Add the powder to the liquid (not the reverse) and mix mechanically to a smooth, lump-free slurry, then apply the first coat by brush or roller, working it well into the surface. Apply the second and, where specified, third coat once the previous coat has firmed up, crossing the brush direction so the full 2.5 to 3.5 kg/m2 builds an even 1.5 to 2.5 mm dry film with no thin spots or pinholes. Reinforce stress points, drains and pipe penetrations. Cure and protect from rain and direct sun, and allow at least 24 hours after the final coat before tiling or overlaying. Always confirm the current mixing ratio, coat count and coverage against the live Sika Technical Data Sheet for the batch supplied.
Specifications
| Product type | Two-component, polymer-modified flexible cementitious waterproof coating |
| Component A | Modified cementitious powder |
| Component B | Sika polymer / latex liquid |
| Elongation at break | Above 80% |
| Crack-bridging capability | Approx. 0.3 to 0.5 mm dynamic crack width |
| Application rate | 2.5 to 3.5 kg/m2 |
| Number of coats | 2 to 3 coats |
| Cured film thickness | Approx. 1.5 to 2.5 mm total (all coats) |
| Overcoating / tiling time | Minimum 24 hours after final coat |
Industry use cases
Residential and housing
Terrace slabs, balconies and bathroom wet areas in apartments and villas, where movement cracking and tile-bed leaks are the usual complaint.
Commercial and institutional
Podium decks, roof terraces and toilet blocks in offices, malls, hospitals and schools that need a bonded membrane under screed or tiles.
Water-retaining structures
Swimming pool shells, sunken slabs, planters and internal tank faces that stay wet and need a flexible, breathable seal.
Repair and rehabilitation
Re-waterproofing of ageing roofs and decks during refurbishment, applied over prepared sound concrete without demolishing the whole slab.
Infrastructure and civil
Retaining wall faces, culvert interiors and other buried concrete exposed to moisture and mild chloride attack.
Frequently asked questions
Is SikaTop 66 flexible or a rigid cement waterproofing?
Do I need a primer before applying it?
How much do I need, and how many coats?
Can I tile directly over it?
Can it be used for swimming pools and water tanks?
Will it stop an already active, moving crack?
How we position Sika SikaTop 66
SikaTop 66 sits in the flexible cementitious waterproofing tier of the Sika range. Where the substrate is stable and you only need a rigid protective slurry, a standard cementitious Sika coating is more economical; where movement and crack-bridging are the concern, this flexible grade is the right call. On wet-area details it pairs naturally with Sika’s swellable waterstops, joint sealants such as Sikaflex, and SikaCeram tile adhesives and grouts over the cured membrane, while SikaGrout handles any anchoring or non-shrink filling around drains and penetrations. Against our other brands, it competes directly with Dr. Fixit’s flexible cementitious coatings and MC-Bauchemie’s polymer-modified membranes; the choice usually comes down to the approved specification on the project and applicator familiarity. Space Arc can supply and apply across all three so the recommendation stays honest to the job rather than the label.
Fosroc Brushbond RFX — Choose the Fosroc Brushbond RFX elastomeric cementitious coating when the project specification or the consultant standardises on Fosroc, or when you want an acrylic polymer-modified system with a well-known local TDS and track record for roofs, tanks and wet areas.
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Source Sika SikaTop 66 for your project
Authorised distribution, technical advice & professional application across Delhi NCR and Pan-India.