Using Ardex Arditex NA Levelling and Smoothing Compound

Using Ardex Arditex NA Levelling and Smoothing Compound

Arditex NA from Ardex is a rapid hardening, ammonia free, latex sub-floor levelling and smoothing compound with improved flow, excellent adhesion, flexibility and water resistance. It can be used with underfloor heating and on most sub-floors including concrete and cement/sand screeds, flooring grade asphalt, quarry tiles, internal steel floors, porcelain tiles and flooring grade plywood. Arditex NA can be laid from a feather edge up to at least 12mm in a single application.

The product requires a mixture of Arditex NA Latex and Arditex NA Powder, both of which are sold separately.


Ensure the surface of the subfloor is clean, sound and clear from dust, paint, grease or loose materials. If you are using Arditex NA over remaining adhesive residues, check to make sure they are not water softenable and that they will withstand the screeding compound. It may be necessary to prime absorbent surfaces with a layer of Arditex NA latex diluted 1 part to 4 parts water with a broom and allow to dry to help reduce suction and pinholes.

A suitable surface damp proof membrane should be applied where rising damp is present, however Arditex NA is unaffected by dampness in the sub-floor as long as there is no surface water. If the sub-floor is impervious or has adhesive residues that will be affected by subsequently applied adhesives, an overall application of Arditex NA at between 3mm and 6mm thick will be required to ensure uniform drying. If using over pitch adhesive residues, first check that they are hard and well adhered enough to support the required thickness of the compound before applying.

Arditex NA can be used toe level timber floors that are rigid but uneven or worn, prior to installing WBP plywood or tile backer boards and new flooring. When using over rigidly fixed flooring grade plywood, Arditex NA can be used as a smoothing layer up to a maximum thickness of 6mm before fitting the final floorcovering with a suitable water-based adhesive.

For gypsum (anhydrite) screeds, ensure it has been tested and contains less than 0.5% moisture content or 75% relative humidity. An appropriate primer should be used to prevent the compound from coming into direct contact with the gypsum screed, as this may have an adverse reaction.


One 20kg bag of Arditex NA should be mixed with one 4.85kg bottle of Arditex NA latex, or 3:1 ratio of powder to latex for smaller quantities. Shake the latex and pour it into a clean mixing container, then gradually add the powder whilst stirring continuously. To aid this use a mixing paddle with a 10mm chuck electric drill.


Once the mixture is ready it should be poured on to the prepared surface and carefully spread with a trowel to the required thickness. This should be applied at temperatures above 5°C, and in one application – not in stages. The use of a spiked roller will improve the surface and performance of the applied mortar whilst still wet.


A standard mix of Arditex NA is suitable for applications from a feather edge up to 12mm, however for thicknesses of 8mm and above an aggregate should be added to help the mix go further.


All tools and mixing containers should be washed and cleaned in water immediately after use before the material sets.

Drying & Hardening

When applied as a 3mm layer at normal temperatures Arditex NA has a working time of approximately 20 minutes, can be walked in in around 2 hours and most floor coverings can be added after 4 hours. The setting, hardening and drying times will be extended or shortened at low or high temperatures respectively, and thicker applications will have an extended drying time.


Coverage varies depending on the texture of the substrate and application thickness, see below table for approximate coverage.

Application ThicknessApproximate Coverage
8mm with aggregate3m2
10mm with aggregate2.3m2

For applications of 8mm and thicker it is recommended to add Ardex Coarse Aggregate to improve coverage.

Storage & Shelf Life

Arditex NA powder has a storage life of 12 months when stored in dry conditions, and Arditex NA latex has a storage life of 6 months when stored in frost-free conditions out of direct sunlight.