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Latex Underlayment

SX301 is a fast setting cement based smoothing product.

SX301 is ideal for use in domestic, light commercial and light industrial environments as an underlayment, prior to application of carpet, wood and vinyl flooring.

  • May accept foot traffic after approximately 90 minutes
  • A low cost viable option in flooring installations
  • Protein free - suitable for use in biologically sensitive areas
  • Extremely low odour with no unpleasant ammonia smell
  • Easy to mix and apply and a smooth surface is produced

Moisture Testing

(in accordance with British Standards 8203)

  • Suitable for application on substrates with <75 % RH.
  • It is recommended that a moisture test is conducted prior to the application of SX302. For further details or to arrange for a moisture test please contact tremco illbruck Technical Services.


  • Subfloor preparation is of key importance with products of this nature.
  • The surface should be free of oil, grease, weak material, laitance andother contaminates.
  • All subfloors, including concrete and highly polished surfaces (e.g. power floated concrete, marble, terrazzo and ceramic tiles), should always be mechanically textured. The floor should then be either vacuumed or swept clean.
  • Sound, stable subfloor construction is essential. The substrate should have a surface pull-off strength of >1.5 N/mm². It is acceptable to apply SX301 to sound, minimised, non-water soluble adhesive residues that are firmly bonded on dry floors only; however, this product is not suitable for application on to bitumen adhesive residues. Bitumen adhesive residues should be completely removed.
  • It is recognised that the success of the system is dependent on the stability and bond of the adhesive to the substrate.


No primer is necessary for absorbent surfaces unless particularly dusty. Use CS150 Acrylic Primer on porous surfaces and CS100 Epoxy Primer on non-porous surfaces.


SX301 can be hand mixed in single units at the ratio of 22 kg powder to 4.3 kg of the supplied latex liquid. Do not add extra liquid as long term performance may be impaired.

After applying the material onto the primed floor, simply use a hand trowel to spread. Maximum application thickness is 6 mm on adhesive residues, or 10 mm on sound substrates.

For full application information, refer to product data sheet or contact tremco illbruck customer services on 01942 251400

Technical data

CompositionCementitious powder and liquid latex dispersion
Pot Life
(at 20°C)
20 minutes
Compressive StrengthAfter 28 days approx. 25 N/mm²

Approx. 5 m² per unit @ 3 mm thickness

Thicknesses of 6 mm to feather edge can be applied dependant on surface profile. An average thickness of 3 mm will provide a coverage rate of 5 m² per mix

Thicknesses of 8 mm to 30 mm can be achieved by incorporating an equal volume of 3 mm granite chippings

This will depend on the condition of the substrate and method of preparation (please refer to tremco illbruck Technical Department)

Cure Time
(at 20°C)
Foot Traffic: 90 minutes
StorageStore in dry, shaded conditions between +5°C and +25°C
Shelf Life6 months when stored as recommended in original unopened packaging
High temperatures and humidity will lead to a reduced shelf life

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