Liquid screed for underfloor heating

Stanbridge Earls, Romsey, Hampshire



Audley Retirement Homes


Henry Construction/ Finnegan Flooring

Location type

Retirement Village


July 2021

The challenge

The Audley Stanbridge Earls retirement village is an exclusive residential development of 155 luxury retirement apartments and cottages designed around a Grade II listed Tudor Manor house on a 32 acre site near Romsey, in Hampshire. Underfloor Heating had been specified as part of the design and the large floor areas now needed to be finished with floor screed that could be installed quickly and efficiently within the operating windows provided by the main contractor. Screed would need to be placed over three floors in the U-shaped building. Access to the site would also be a challenge. After discussions between the flooring contractor and Tarmac’s Technical Sales Representative TOPFLOW Screed A, a high-performance liquid anhydrite screed was recommended as the ideal solution. 

Our solution

TOPFLOW Screed A is available in a number of alternative mixes with specific performance characteristics to help with the specific challenges faced by the contractor. As a flowing, self-compacting screed it can quickly pumped into place over large floor areas and can receive foot traffic within 24-48 hours allowing other trades to continue working. TOPFLOW Screed A Thermio + offers a higher thermal conductivity than conventional sand-cement screeds, can be laid thinner and fully encapsulates heating pipes without leaving any voids. This makes it ideal for use with underfloor heating systems where it helps to improve the thermal performance and energy efficiency of buildings. TOPFLOW Screed A LL (low laitance) offers faster drying times and less surface laitance, reducing the amount of sanding required and allowing floor finishes to be installed more quickly.

Results and benefits

Around 123m3 of TOPFLOW Screed A Thermio and just over 100 m3 TOPFLOW Screed A LL (low laitance) was supplied and installed during 10 pours over a 7 week period, scheduled to fit within the build programme. Technical support was provided throughout, with Tarmac Tarmac’s Technical Sales Representative on site to ensure compliance with specification and make sure that the client got the best possible finish. As expected, the fast-drying times and early trafficking characteristics of TOPFLOW Screed A enabled other trades to follow on quickly, providing continuity and efficiency within the client’s build programme. All TOPFLOW Screed A products are made from gypsum and are completely cement free, with a binder made from 98% recycled material. This gives it a lower carbon footprint than a conventional cement-based screeds, saving up to 20.45kg CO2e per m2, making it a more sustainable choice.

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Additional information:

Flowing screed with improved thermal conductivity

Topflow Screed A Thermio + is the only thermal screed with a guaranteed minimum thermal conductivity backed by BBA. For underfloor heating it offers a Thermal conductivity of 2.5 W/m.K *(Nominal Value) and up to a 30% increase in thermal emission and up to 80% of thermal diffusivity for faster increase of temperature.

Liquid screed for underfloor heating contact

Topflow Screed A Thermio+ case studies