STP ShaliFloor SL UL 1C-R
A ready-to-use, single-component lightweight cementitious self-levelling underlay that turns rough, out-of-tolerance concrete into a smooth, flat base for tiles, vinyl and resin floor systems.
What is it?
A single-pack, polymer-modified cementitious self-levelling underlay from STP that only needs clean water to become a free-flowing, self-smoothing slurry.
Where is it used?
Interior floors in homes, offices, showrooms, shops, hotels and light-to-medium duty commercial spaces where a level base is needed before the final finish.
Why use it?
It corrects undulations and surface defects quickly, giving a flat, dust-free plane so tiling, vinyl, carpet or resin toppings go down evenly without hollows or lippage.
How is it applied?
Mix roughly 4.5-5 litres of water per 25 kg bag, pour onto a primed substrate and let it flow out to 3-10 mm; it self-levels with minimal trowelling and is walk-on-ready within a few hours.
About STP ShaliFloor SL UL 1C-R
STP’s ShaliFloor SL UL 1C-R is built for a job every flooring contractor knows too well: the concrete base is never as flat as the specification demands. Screeds cure with falls and ridges, power-float marks leave the surface uneven, and older slabs carry years of patch repairs. Laying a premium tile, vinyl or epoxy finish over that kind of substrate is asking for hollow tiles, visible lippage and a floor that fails inspection. This single-component underlay exists to close that gap. It arrives as a dry grey powder in a 25 kg bag, and the only site input is clean water, which keeps mixing errors low and makes it practical for crews who do not have gauging equipment or a second component to measure.
Once gauged at the recommended 4.5-5 litres per bag, the material becomes a mobile, self-seeking slurry that flows across the floor and finds its own level with very little trowelling. It is formulated as an ultra-lightweight, polymer-modified topping, so it builds a smooth plane from 3 mm up to 10 mm in a pass while staying flexible enough to resist the fine cracking that plagues rigid levelling mortars. The cured surface reaches around 25 MPa in compression, resists abrasion and foot traffic, and cuts down the dusting that untreated concrete throws off. For light-to-medium duty interiors, it is the layer that lets the finish floor perform the way its manufacturer intended.
The technical insight
The performance comes from the polymer-modified, lightweight cementitious matrix rather than plain cement and sand. The polymer fraction does two things: it boosts adhesion to the concrete below so the layer keys in and does not delaminate, and it adds a degree of flexibility that absorbs minor movement instead of transmitting it into cracks. The lightweight, graded formulation is engineered for flow, so surface tension and self-weight pull the slurry into a level plane once poured, per the flow behaviour measured under EN 12706. Because it is single-component, the polymer and all reactive constituents are pre-blended into the powder and activate on contact with water, which removes the site variability of two-part or liquid-latex systems. The trade-off is a working window of roughly 30 minutes of pot life, so the material is designed to be mixed, poured and levelled in continuous, well-planned batches.
Where it is used
- Levelling and smoothing uneven concrete floors before tiling, vinyl or carpet
- Preparing a flat, sound base ahead of epoxy or PU resin topcoats
- Renovating old, worn or patched concrete slabs in occupied buildings
- Correcting falls and undulations in newly laid screeds
- Flooring in offices, retail showrooms, shops and reception areas
- Light-to-medium duty commercial interiors such as hotels and clinics
- Residential floors where a smooth base for premium finishes is required
- Refurbishment work where a fast walk-on-ready underlay keeps the site moving
Key advantages
- Single-component and ready to use; only clean water is added, reducing mixing errors on site
- Self-levelling flow gives a smooth, flat plane with minimal trowelling
- Builds 3-10 mm in a single pour, covering a useful range of substrate deviations
- Ultra-lightweight, polymer-modified matrix bonds well and resists shrinkage cracking
- Reaches around 25 MPa compressive strength for durable light-to-medium duty service
- Good abrasion resistance and low water absorption for a hard, long-lasting surface
- Suppresses dusting from raw concrete, giving a cleaner base for finishes
- Fast walk-on time keeps multi-trade programmes on schedule
Limitations & considerations
- Intended for light-to-medium duty interiors, not heavy industrial or vehicular-traffic floors
- Short pot life of about 30 minutes demands disciplined, continuous batching and pouring
- Single-pour thickness is capped at 10 mm; deeper build-ups need a screed or thick-bed compound first
- Not a wearing course or final finish on its own; it needs tiles, resin or another topping over it
- Requires a sound, primed and contamination-free substrate for reliable adhesion
- Placement is temperature-sensitive and should be done within the 5-35 degrees C window
Selection & best practice
Success with a self-levelling underlay is decided before the first bag is opened. Grind or shot-blast the concrete to remove laitance, curing compounds and old adhesive, then vacuum it clean; the surface must be sound, dry and free of oil or dust. Prime the substrate with a compatible primer and let it become tacky so the underlay bonds instead of pinholing. Gauge only clean water at 4.5-5 litres per 25 kg bag, mix with a slow-speed paddle to a lump-free, flowable slurry, and pour promptly because the roughly 30-minute pot life leaves no room to wait. Work in a planned sequence, feathering wet edges into fresh material, and use a spiked roller to release trapped air. Keep the slab and the ambient temperature within 5-35 degrees C, protect the fresh floor from draughts and direct sun, and let it cure fully before laying the finish. For thicker corrections, level in stages or use a thick-bed compound underneath rather than exceeding 10 mm in one pass.
Specifications
| Product type | Single-component, polymer-modified cementitious self-levelling underlay |
| Colour | Grey |
| Bulk density | Approx. 1750 kg/m3 |
| Compressive strength | Approx. 25 MPa at 28 days (ASTM C109) |
| Tensile strength | Approx. 4 MPa at 28 days (ASTM C190) |
| Water absorption | Low (ASTM C642) |
| Mixing ratio | 4.5-5 litres clean water per 25 kg bag |
| Application thickness | 3-10 mm per pour |
| Pot life | Approx. 30 minutes |
| Pack size | 25 kg bag |
Industry use cases
Retail and showrooms
Flattens the base beneath large-format tiles or vinyl so display floors read as one clean plane without lippage or hollow spots.
Offices and commercial fit-outs
Corrects screed undulations before carpet tiles or resilient flooring, helping the finish sit flat and wear evenly under daily foot traffic.
Hospitality and clinics
Provides a smooth, dust-free, walk-on-ready base for light-to-medium duty interior floors where downtime must be kept short.
Residential renovation
Renovates old or patched slabs in occupied homes, giving a level surface for premium tile or wood-look finishes.
Resin flooring preparation
Delivers the flat, sound substrate that epoxy and PU topcoats need so the resin cures to an even film without telegraphing defects.
Frequently asked questions
What thickness can I apply in one pour?
How much water do I add per bag?
Is this a finished floor or a base layer?
Can it take heavy industrial traffic?
How long is the working time after mixing?
Do I need to prime the concrete first?
How we position STP ShaliFloor SL UL 1C-R
ShaliFloor SL UL 1C-R sits at the underlay stage of a full STP flooring build-up, so it pairs naturally with the rest of the ShaliFloor range that Space Arc supplies. Once it has levelled the base, the finish coat typically comes from STP’s epoxy toppings such as ShaliFloor SL TC 2E or the SL UL 3 ES self-levelling epoxy, or from the ShaliFloor TC 2PU and SL 3EPU polyurethane systems where chemical or abrasion resistance matters; ShaliPrime 2EC is the companion primer that keys these layers together. Where the correction runs deeper than 10 mm, step up to ShaliFloor Screed for the heavy build before finishing. As authorised distributors across multiple construction-chemical brands, we can also cross-specify equivalents from Fosroc, Sika, MC-Bauchemie and Dr. Fixit when a project standard or approved-vendor list calls for a particular make, so you get the right underlay for the specification rather than whatever is on the shelf.
Fosroc Nitoflor Levelcrete — Choose the Fosroc option when the project’s approved-vendor list specifies Fosroc, or when you need a thicker single-pour build-up than this STP underlay’s 10 mm limit allows.
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Authorised distribution, technical advice & professional application across Delhi NCR and Pan-India.