Fosroc Renderoc ST05

Protective cementitious coating and levelling mortar for applications from feather edge to 5mm conforming to the requirements of BS EN 1504-3 Class R4

For application in thin layers, the filling of blow-holes or imperfections in concrete to produce a smooth surface. Providing a chloride and carbonation barrier. It can be left as a fair-face finish or overcoated.
It can be used as a scrape-coat, brush or trowel applied, placed in thicknesses from 0-5 mm.
Renderoc ST 05 is suitable for repair methods: 1.3, 2.2, 5.1, 6.1 and 8.2 as defined by BS EN 1504-2:
3.1, 7.1 and 7.2 as defined by BS EN 1504-3


  • Easy to mix and apply
  • Vertical and horizontal applications
  • Excellent bond to concrete without priming
  • Formulated blow hole filler
  • Carbonation barrier
  • Chloride barrier
  • High frost resistance
  • High compressive strength

Renderoc ST 05 consists of powder and polymer components The powder is added to the liquid, the mixing ratio depends on the required consistency and use. The powder consists of a blend of cements, graded aggregates and chemical additives, with a maximum grain sizes of 0.5 mm The liquid component, based on modified acrylic polymers, gives Renderoc ST 05 a creamy consistency with extremely good application and barrier characteristics.
The product exhibits excellent thermal compatibility with concrete and is fully compatible with other Renderoc mortars and Dekguard coatings.
Exposure to rainfall prior to the final set may result in water uptake and severe reduction in the performance of the hardened product. Exposure to mist or high humidity prior to sufficient hardening may result in discolouration of the surfaces. These white discolourations will decrease with time

Surfaces must be clean and sound, with no traces of loose material, cement paste, laitance, dust, plaster, oil, grease, corrosion deposits or algae.
Prepare the surfaces by abrasive grit blasting or light scabbling. Remove oil and grease with suitable detergent. Finally the cleaned surfaces should be blown clean with oil
free compressed air before continuing. On floors, large pockets greater than 4 mm depth should be filled with Fosroc XR90, finished with a scratched surface.
Allow one hour to cure before application of Renderoc ST 05.

Renderoc ST 05 can be applied by brush, roller or trowell depending on consistency and application.
The surface finish of the final coat can be obtained in the
following ways:
I) Smooth surface: Finish with a sponge.
II) Rough, granulated surface: Finish with a roller.
III) Skid resistant surface: Sprinkle dry quartz sand in the
wet surface or brush finish.