This site uses cookies to store information on your computer. Learn more about these cookies, and how to opt out of them. Find out more

NBS Source

Topflow Screed C

Verified by manufacturer 11 months ago


Free-flowing cement based screed suitable for most applications including underfloor heating and wet environments.

Jump to:
0121 787 5001


Suitable for all residential and commercial floors carrying pedestrian traffic within BS 8204 classification.


Designed to provide a smooth level surface in both commercial and domestic buildings prior to the application of floor finishes, It can be unbonded or floating. Also suitable for use with underfloor heating.

Features and benefits:

  • It is a more conductive medium than sand cement screed and is self-curing and self-compacting.
  • It can be laid thinner than competing sand cement systems without detriment to its performance, so any underfloor heating pipes are closer to the surface (nominal cover to pipes 30 mm).
  • No need for force drying as the product is ready to receive floor coverings within 14–21 days dependent on environment.
  • It can be laid as a floating construction over most types of rigid insulation board or acoustic matting at a minimum thickness of 40 mm.
  • It offers significant programme benefits, as areas of up to 120 m² can easily be installed and finished per hour.
  • It's very low shrinkage values mean you require less construction joints than cement based screeds.
  • The screed can receive foot traffic 48 hours after placement.
  • The product can remain fluid for two hours.
  • Easily achieves SR2 under BS 8204. Not suitable as a wearing surface, or for external areas.
  • Compatible with all floor coverings, and also compatible with all cementitious adhesives and floor levellers.
  • Flow range: 270–280 mm.
  • Fire rating (BS 476-4) non-combustible.

General information








Pr_35_31_06_78 Self-smoothing levelling screed mixesPrimary


M10/160 Proprietary self smoothing levelling screeds

Specification data - Self-smoothing levelling screed mixes


Dark Grey fluid mortar.


2200 kg/m³, 2000 kg/m³.

  • Wet: 2200 kg/m³.
  • Dry: 2000 kg/m³.

Compressive strength - 28 days

25 N/mm².

Flexural strength

Flexural strength at 28 days

4 N/mm².


1.7 W/m·K.

Screed thickness

50 mm.


35 mm.

Floating over thermal insulation: Residential.

40 mm.

Floating over thermal insulation: Commercial.

30 mm.

Cover to heating pipes.


Screed C Belitex CT16/F2.

Screed C Belitex CT20/F4.

Screed C Belitex CT25/F4.

Drying time

14–21 days, 48 hours.

  • 14–21 days: ready to receive floor coverings.
  • 48 hours: receive foot traffic.


120 m²/hour.

Case studies

Cement based floor screed solution for underfloor heating

Cement based floor screed solution for underfloor heating