UltraTech Seal & Dry Hi-Flex
A two-component elastomeric cementitious coating engineered for large-format, high-risk positive-side waterproofing — terraces, pools, tanks and facades beyond 10,000 sq ft.
What is it?
A two-component, cement-based, acrylic-emulsion elastomeric coating. Powder and polymer liquid are mixed on site and brushed on to form a flexible, crack-bridging waterproof membrane over concrete, stone and masonry.
Where is it used?
Terraces, sloping roofs, balconies, domes, swimming pools, sump tanks and exposed facades — particularly on large commercial, hospitality and institutional projects.
Why use it?
Elongation beyond 100% lets the membrane stretch across shrinkage and hairline cracks instead of tearing, while a 1 mm dry film holds back water pressure up to 7 bar.
How is it applied?
Blend roughly 1.4 parts powder to 1 part acrylic liquid by weight, then brush on two coats of about 0.4–0.5 mm each, laying the second at right angles to the first.
About UltraTech Seal & Dry Hi-Flex
UltraTech Seal & Dry Hi-Flex sits at the top of UltraTech’s Seal & Dry cementitious waterproofing range, built for jobs where area, exposure or risk rule out a lighter system. It is a two-component product — a cementitious, polymer-fortified powder hand-mixed on site with an acrylic-emulsion liquid — and once cured it behaves less like a rigid cement coat and more like a tough, rubbery skin bonded to the substrate. Ordinary cementitious slurries crack the moment the concrete beneath them moves, but a membrane that stretches past 100% keeps working through seasonal expansion, minor settlement and the hairline cracks that show up on any large exposed slab.
Space Arc positions Hi-Flex for projects crossing the 10,000 sq ft mark — think institutional terraces, hotel pool decks, basement sump pits and podium waterproofing — where the smaller-batch Seal & Dry Flex, rated at 50% elongation, would mean too many mixing cycles and too much seam risk. Hi-Flex is applied, cured and pressure-tested the same way, just scaled for bigger, higher-stakes substrates.
The technical insight
The two numbers worth remembering on a Hi-Flex job are the mix ratio and the pot life. At roughly 1.4 parts powder to 1 part liquid by weight, a 12 kg pack yields enough mixed compound for a modest bay; the 24 kg pack scales up for bigger daily pours. Pot life runs to about two hours, so applicators on large terraces typically mix in smaller batches through the day rather than one large batch that starts skinning before it is brushed out.
Coverage works out to roughly 14–15 sq ft per kilogram of mixed compound across two coats, each laid at 0.4–0.5 mm dry film thickness, together landing close to the 1 mm DFT at which the coating is rated for 7 bar water pressure. Thinner-than-specified coats will pass a quick visual check but will not deliver that pressure rating. After the second coat, UltraTech recommends waiting roughly 3–4 days before normal use, and at least 72 hours before a ponding test; rushing either step is the most common cause of early comebacks.
Where it is used
- Terraces and podium decks on large commercial or institutional buildings
- Swimming pools and sump tanks in hotels, hospitals and residential high-rises
- Sloping roofs, balconies and domes exposed to standing or driving rain
- Exterior facades facing wind-driven rain in coastal or high-rainfall zones
- Sunken wet areas — bathrooms, kitchens, utility decks — before screeding
- Positive-side waterproofing over concrete, natural stone, marble and granite substrates
Key advantages
- 100%+ elongation bridges hairline and shrinkage cracks that would split a rigid cementitious coat
- Rated to hold back 7 bar of water pressure at just 1 mm dry film thickness
- Bonds directly to concrete, natural stone, marble and granite without a separate primer coat
- Breathable film lets trapped vapour escape instead of blistering the coating
- Non-toxic and non-flammable, straightforward to store and handle on live sites
- Tolerant of occasional foot traffic and incidental exposure to domestic wastewater
Limitations & considerations
- Formulated for positive-side use only — not a substitute for negative-side, below-grade waterproofing systems
- Pot life of about two hours means large pours need batch-mixing discipline, especially in hot weather
- Needs a sound, contamination-free substrate; loose plaster or laitance undermines adhesion regardless of coat quality
- Not a structural crack or movement-joint solution; genuine expansion joints still need a dedicated sealant system
- Full service readiness takes days: normal use after 3–4 days, ponding tests only after 72 hours
Selection & best practice
Wire-brush and jet-wash the substrate to remove laitance, dust and curing compound before mixing. Many applicators prime absorptive concrete or plaster with an integral waterproofing liquid first, since a porous substrate can pull moisture out of the coating before it cures. Mix only what you can apply within the pot life — roughly two hours — to a lump-free, brushable consistency, and hold to two full coats rather than one thick coat. Apply the second coat perpendicular to the first once it has firmed up, and protect the finished membrane from rain and foot traffic through the curing period.
Specifications
| Product Type | Two-component, cement-based, acrylic-emulsion elastomeric waterproof coating |
| Elongation | 100%+ at 50 kg/cm² tensile force |
| Water Pressure Resistance | Up to 7 bar at 1 mm DFT |
| Mix Ratio | ~1.4 parts powder : 1 part acrylic liquid, by weight |
| Coats & Film Thickness | 2 coats, ~0.4–0.5 mm DFT each (~1 mm total) |
| Coverage | ~14–15 sq ft per kg of mixed compound (2 coats) |
| Pot Life | ~2 hours |
| Pack Sizes | 12 kg and 24 kg |
| Shelf Life | 12 months from manufacture, stored cool and dry |
| Recommended Substrates | Concrete, natural stone, marble, granite |
| Curing Before Use | Normal use after 3–4 days; ponding test only after 72 hours |
Industry use cases
Hospitality & Institutional
Pool decks, terraces and podium waterproofing on hotels, hospitals and campuses where downtime for repairs is not an option.
High-Rise Residential
Sump tanks, common terraces and exposed facades on towers where the waterproofed area routinely exceeds 10,000 sq ft.
Industrial & Commercial Roofs
Large flat or sloping roof decks needing a single flexible membrane rather than multiple smaller batches.
Renovation & Retrofit
Re-waterproofing aging terraces and balconies where existing cracking has already telegraphed through older rigid coatings.
Frequently asked questions
How is Hi-Flex different from the standard Seal & Dry Flex?
Can it go directly over old tiles or a failed waterproofing layer?
Is it suitable for a basement wall holding back groundwater?
How soon can the area be put back into service?
Does it need a primer?
How we position UltraTech Seal & Dry Hi-Flex
Within Space Arc’s UltraTech waterproofing lineup, Hi-Flex is the specification default whenever the job crosses roughly 10,000 sq ft, involves standing water, or carries more consequence if it fails — pool decks, hospital wet areas, high-rise podiums. For smaller residential terraces or balconies, the standard Flex variant covers the same chemistry at a lower elongation and a lower cost per square foot. Consultants comparing brands will find UltraTech’s dealer network and pricing straightforward across India, often the deciding factor once elongation, pressure rating and coverage are already satisfied.
Fosroc Brushbond RFX — Specifiers needing a potable-water-compatible, breathable coating for tanks or substrates with smaller static crack widths (around 1 mm) may prefer Brushbond RFX, while Hi-Flex’s higher elongation stays the better fit for large, high-movement exterior areas.
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