Atlas ZW 330 Fast Setting Leveling Mortar 25 kg — Fibre-Reinforced Repair and Levelling Compound

Product Overview

A single 25 kg bag of Atlas ZW 330 Fast Setting Leveling Mortar repairs and levels building substrates indoors and outdoors — filling cavities, reconstructing corners, and forming slopes with a rapid 5-hour setting time — delivering high compressive strength of ≥ 20 MPa and flexural resistance of ≥ 4.0 MPa for professional UK building preparations. Part of the EPS adhesive and basecoat range at Renders World — the professional collection covering everything from substrate preparation to insulation bonding — this premium cement-based compound is fortified with polypropylene microfibres to prevent shrinkage cracks, making it the preferred choice for tradespeople preparing walls and floors for final finishes.

Each bag covers significant repair areas with a flexible thickness range of 3 to 30 mm in a single pass, which can be extended up to 60 mm when mixed with quartz sand. Compatible with cement plasters, concrete, aerated concrete, and unplastered masonry, Atlas ZW 330 provides the perfect stable base for ceramic tiles, thin-coat plasters, or floor panels, significantly reducing the wear and tear on subsequent adhesive and finishing layers.

Key Benefits

• Rapid 5-Hour Setting Time: Allows subsequent trades to begin work quickly, meaning ceramic tiles can be laid just 5 hours after applying a 5 mm layer under normal conditions — accelerating project timelines and reducing site downtime.
• Crack-Resistant Fibre Reinforcement: Built-in polypropylene microfibres distribute structural stress during the curing process, effectively eliminating shrinkage cracks and allowing thicker layers to be applied to vertical surfaces without any slumping or run-off.
• Versatile Thickness Range: Handles everything from minor surface smoothing at 3 mm up to deep structural fills at 30 mm in a single application — with the option to bulk out the mix with quartz sand for massive 60 mm cavity repairs.
• High Mechanical Strength: Cures to an exceptionally hard surface with compressive strength exceeding 20 MPa and flexural strength above 4.0 MPa, ensuring the repaired area holds firm under heavy loads and structural movement for the full life of the building.
• Multi-Purpose Application: Performs reliably across a massive range of tasks — from reconstructing balcony edges and window reveals to filling plumbing chases, shaping facet slopes, and preparing subfloors for final coverings.
• Universal Substrate Compatibility: Bonds aggressively to all standard mineral building materials including cement-lime plasters, aerated concrete blocks, ceramic bricks, and existing cement screeds, making it a universal repair solution for any site.

Technical Specifications

Property	Value
Product Type	Fast-setting cement-based repair and levelling mortar
Composition	Cement binder, quartz fillers, polymer additives, polypropylene fibres
Pack Size	25 kg bag
Colour	Grey
Layer Thickness (Standard)	3–30 mm
Layer Thickness (With Sand)	31–60 mm (1:4 sand to dry mortar ratio)
Tile Laying Time	Approx. 5 hours (at 5 mm thickness)
Compressive Strength	≥ 20 MPa
Flexural Strength	≥ 4.0 MPa
Application Temperature	+5 °C to +25 °C (substrate and ambient)
Application Method	Trowel (hand)
Shelf Life	12 months in dry conditions, original sealed packaging

Application & Compatibility

Atlas ZW 330 performs best when applied to clean, structurally sound mineral substrates that are free from dust, grease, bitumen, and loose materials that could compromise adhesion. For a complete system approach, pair this levelling mortar with a deep-penetrating render primer to regulate substrate suction before application, ensuring an even cure and maximum bond strength across the entire repaired area. For a broader overview of how substrate preparation products fit into a complete EWI system, our guide to choosing the right adhesive for EPS projects covers the full material stack from levelling mortar through to decorative render.

• Substrate Preparation: Mechanically remove any loose plaster, brittle concrete, or peeling paint. A coat of primer on highly absorbent substrates — such as aerated concrete or older ceramic blocks — regulates suction evenly so the mortar cures at full strength without drying out too quickly.
• Mixing and Application: Pour the dry powder into the measured amount of clean water and mix with a slow-speed drill paddle until a uniform, lump-free plastic consistency is achieved. Apply the mortar firmly using a steel trowel, pressing it into cavities to ensure full contact with the substrate.
• Deep Cavity Filling: For voids deeper than 30 mm (up to 60 mm), blend the dry mortar with clean quartz sand (up to 2 mm grain size) at a 1:4 weight ratio. This bulking technique provides the necessary volume for deep repairs without compromising the structural integrity of the cure.
• System Context: Once the Atlas ZW 330 has fully cured and dried, the surface provides a perfectly flat, high-strength canvas for flexible tile adhesives, decorative thin-coat plasters, or floor levelling compounds. If you are preparing walls for insulation bonding, this strong substrate is ideal for follow-up EPS adhesives such as Atlas Hoter U grey 25 kg.

Installation Notes

For the strongest possible bond on smooth or low-absorption concrete surfaces, apply a specialized bonding primer (contact bridge) before laying the mortar. Keeping the freshly applied levelling layer sheltered from direct sunlight, strong draughts, and rapid drying during the first 24 hours — with ambient and wall surface temperatures between +5 °C and +25 °C — gives the cement matrix the stable curing conditions required to reach its full 20 MPa strength without surface crazing.

Trade Insight — Installer's Note

The standout advantage of Atlas ZW 330 on a busy site is its genuinely rapid 5-hour setting time for standard 5 mm layers. Unlike traditional sand-and-cement mixes that force you to abandon the wall until the next day, this mortar allows you to fill chases, repair window reveals, and reconstruct damaged corners in the morning, and begin laying ceramic tiles over the exact same areas after lunch. The inclusion of polypropylene fibres is another massive benefit — the mortar holds its shape perfectly on vertical edges without slumping, saving you the time and frustration of constantly re-trowelling sagging corners.

Is This Product Right for Your Project?

• Choose Atlas ZW 330 25 kg if you need a high-strength, rapid-setting mortar to repair deep cavities, reconstruct corners, or level floors and walls, and you want to proceed with tiling or plastering on the same day.
• Need a breathable bond for mineral wool? If you have repaired the wall and are now moving straight onto A1 fire-rated insulation, switch to a dedicated product such as Roker U grey 25 kg to secure the heavy mineral slabs safely.
• Working with extremely thin surface skimming? If your wall deviations are less than 3 mm, a fine finishing putty or dedicated skimming plaster will provide a smoother final surface than a structural repair mortar.

Frequently Asked Questions

How many bags of Atlas ZW 330 do I need for my repair project?

Consumption depends entirely on the depth of the cavities and the thickness of the levelling layer required. As a general benchmark, expect to use approximately 1.5 kg of dry powder per 1 m² for every 1 mm of layer thickness. For a 10 mm thick levelling coat over 1 square metre, you will need 15 kg of mortar — meaning a single 25 kg bag covers approximately 1.6 m² at that depth.

Can I use Atlas ZW 330 outdoors on balconies and terraces?

Yes, Atlas ZW 330 is fully frost-resistant and waterproof once cured, making it an excellent choice for outdoor applications. It is frequently specified for repairing balcony slab edges, reconstructing exterior stair corners, and forming essential drainage slopes (facets) prior to applying waterproofing membranes and exterior tile adhesives.

How soon can I lay tiles after applying the mortar?

One of the primary benefits of this fast-setting formulation is that ceramic tiles can be laid after approximately 5 hours, provided the mortar layer is around 5 mm thick and applied under normal room temperatures (20 °C). Thicker applications, colder conditions, or high humidity will extend this waiting period.

Do I need to add sand for every application?

No, adding quartz sand is only required for exceptionally deep repairs. For standard levelling and filling between 3 mm and 30 mm, use the mortar exactly as it comes out of the bag. If you need to fill a massive cavity up to 60 mm deep, blending in quartz sand (at a 1:4 sand-to-mortar ratio) safely bulks out the mix to prevent cracking in ultra-thick layers.

Is Atlas ZW 330 safe to handle during mixing?

Atlas ZW 330 is a cement-based product, which means the wet mixture is highly alkaline. Installers must wear standard protective equipment, including gloves and safety glasses, to prevent skin and eye irritation during mixing and application. Once the mortar has fully cured, it is completely inert and poses no environmental or health risks.