About STP ShaliFloor SL UL 3 ES

ShaliFloor SL UL 3 ES is STP Limited’s epoxy self-levelling underlay screed (the product many older specifications still list as ShaliScreed SL UL). It is a three-component system – resin, hardener and a pre-blended filler/aggregate pack – supplied in matched, pre-weighed quantities so that the correct mix ratio is achieved on site every time, without site batching or guesswork. Mixed and poured, it flows out under its own weight to a smooth, flat plane at a typical 1 to 3 mm build, filling the minor undulations and trowel marks that almost every concrete slab carries.

Its job is deliberately narrow and important: it is an underlay, not a finish. Rather than being the wearing surface, it corrects the profile of the substrate so that the epoxy screed, self-levelling topping or coating laid over it sits on a true, sound base. A flat underlay means the topcoat can be pulled down to its designed film thickness instead of chasing hollows, which protects both the appearance and the material budget of the finished floor. Bonding strongly to concrete and keying well to the subsequent finish, it becomes an integral part of the flooring build-up rather than a sacrificial layer.

The technical insight

The value of a self-levelling underlay lies in the physics of the pour. Because the material is formulated to flow rather than to be worked, gravity and surface tension do the finishing – the liquid seeks its own level and bridges the small dips and ridges that a floated slab inevitably has. Getting there depends on two things being right: an accurate resin-to-hardener-to-filler ratio, and a controlled viscosity. STP addresses the first by pre-weighing all three components, removing the commonest site error in reactive flooring. The cured film develops a compressive strength above 50 MPa, comfortably harder than most substrate concrete, so the underlay does not become the weak link when point loads or traffic pass through to the slab. Equally important is the interface: the epoxy wets into the primed concrete to form a monolithic bond below, while its slightly open, screed-textured top face gives the mechanical key the topcoat needs to grip. The result is a layered floor that behaves as one composite section rather than three loosely stacked coats.

Where it is used

• Levelling and truing uneven or worn concrete before an epoxy or PU finish
• Correcting slab profile in pharmaceutical and healthcare manufacturing floors
• Base preparation for clean rooms and controlled-environment areas
• Underlay for laboratory, assembly and light-engineering floors
• Renovation of old industrial slabs ahead of a new coating system
• Smoothing substrates such as concrete, Kota stone and marble prior to topping
• Reducing topcoat consumption on floors where a high-build finish is specified

Key advantages

• Pre-weighed three-part packs deliver the correct mix ratio every time, with no site batching
• Self-levelling flow removes hand-trowelling and the ridges it leaves behind
• High compressive strength above 50 MPa gives a hard, load-bearing base
• Bonds strongly to concrete below and keys well to the finish above
• A true, flat surface lets the topcoat sit at its designed thickness, saving material
• Walk-on in roughly 4 hours at 25 C keeps multi-coat programmes moving
• Suits demanding, hygiene-sensitive environments such as pharma and clean rooms

Limitations & considerations

• It is an underlay, not a wearing surface – it must be finished with an epoxy or PU topcoat
• Do not lay it over asphalt, weak or friable concrete, unmodified sand/cement screeds or PVC tiles/sheets
• Not for substrates that move substantially, such as steel walkways
• Not to be used where rising damp, osmotic risk or relative humidity above 75% is present, unless a suitable DPM is installed
• Application is restricted to a substrate temperature window of roughly 10 C to 45 C
• Being reactive and pre-weighed, mixed material has a limited working time and full packs should be used at once

Selection & best practice

Specifications

Industry use cases

How we position STP ShaliFloor SL UL 3 ES

Position ShaliFloor SL UL 3 ES as the levelling underlay layer within STP’s ShaliFloor system, not as a stand-alone floor. It pairs naturally with STP epoxy and PU wearing finishes from the same family – such as the ShaliFloor SL topping and screed range (for example ShaliFloor SL T 3 ES) – laid directly over the cured underlay. Where the specification calls for a Fosroc build-up instead, or where the client already standardises on Fosroc’s Nitoflor line, the equivalent function is served by an epoxy screed such as Nitoflor ET Screed. For a purely cementitious levelling underlayment beneath tile, vinyl or carpet – rather than an epoxy base under a resin topcoat – point the customer to a self-smoothing compound like Fosroc Nitoflor Levelcrete, which is a different chemistry for a different job.

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