NBS Source


  • The product can be installed over timber floors of sufficient structural support, Lewis decking, and in situ and precast concrete flooring substrates including concrete planks and block and beam systems.
  • Suitable for use with both warm water and electric underfloor heating systems that use conventional heating sources and renewable technologies. A screed with higher thermal conductivity will heat up and cool down more rapidly providing greater system control and improve comfort levels.
  • Suitable for new build and refurbishment projects.

Supaflo HTC should only be used if the building envelope is complete; doors and windows should be in place and must be closed for the first 24 to 48 hours after installation to prevent drafts blowing across the surface of the screed.


Supaflo HTC is a self-compacting flowing screed based on an anhydrite binder. It is specifically intended for use with underfloor heating systems and is formulated to provide a floor with higher thermal conductivity when compared to traditional cement, sand screed and regular flowing screed.

The product can help improve the sustainability criteria when compared to conventional screeds, it can also be installed with a minimum cover to the underfloor heating pipes of 20 mm, subject to substrate suitability. At this reduced cover some differential settlement may occur.

It is recommended the screed is lightly sanded prior to overlaying and is compatible with all types of floor covering.

Features and benefits:

  • The product is delivered to site ready mixed.
  • Forced drying: Can be forced dried after seven days using the underfloor heating system or temporary dry source heater or dehumidifiers. Forced drying will reduce drying times.
  • Volatile organic compound (VOC): Virtually zero.

General information





Anhydrite binder

Uniclass 2015

Pr_35_31_06_73 Ready-mixed trowelled calcium sulfate screedsPrimary


M13/10 Proprietary trowelled levelling screeds

M13/110 Proprietary trowelled levelling screeds

Specification data - Ready-mixed trowelled calcium sulfate screeds Enhanced data


Ready mixed.


Off-white fluid mortar.


Plastic: 2150–2250 kg/m³; Dry: 1950–2050 kg/m³.

Compressive strength - 28 days

CA C30–F5.


230–270 mm.

 (BS8204:7 Annex A, Truncated cone).


Samples prepared using reference sand tested by Warwick University to ASTM 1530 achieved 2.5 W/mK. For UK calculation a value of 2.3 W/mK is recommended.


Working time

Batched, transported, placed and finished within three hours.


Five to seven days.

Drying time

Approximately 1 mm per day up to 40 mm, then 0.5 mm per day.


Floating including underfloor heating – 20 mm cover above pipes or cables. Most underfloor heated screed are installed 45 to 55 mm thick.


Curing time

24 to 48 hours.

Environmental information

Embodied carbon

Binder 10–20 kg per tonne.




Recycled content

Binder: 98%. Mortar up to 40%.



Supaflo HTC - High Thermal Conductivity Flowing Screed

Supaflo HTC - High Thermal Conductivity Flowing Screed

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