Case Study: Liquid Floor Screeding Over Underfloor Heating in Nailsea

Nailsea, North Somerset

45m² Cemfloor Therm C20 liquid screed installation

Underfloor heating to existing property & new extension

For this floor screeding project we used:

• Cemfloor Therm C20 cement-based liquid screed
• Approximately 45m² of floor area
• Screed depths ranging from approximately 50mm to 90mm
• Existing and new underfloor heating installation
• Putzmeister SP11 specialist screed pump
• Laser-controlled floor levels
• Dappled finish to produce a smooth, level surface

The property in Nailsea, North Somerset was undergoing a major ground-floor renovation and extension to create a larger open-plan living space.

As part of the project, the existing floor had been removed and the builder and plumber installed underfloor heating throughout both the original property and the new extension.

The challenge was to screed the two areas as one continuous floor, creating a flat and consistent finished level across the newly opened-up space.

A key requirement was achieving a screed level exactly 20mm below the new door threshold, allowing the correct depth for the final tiled floor finish.

Before the screed installation, the floor preparation and underfloor heating system were completed by the builder and plumber.

Because the existing property had been knocked through into the new extension, establishing the correct finished floor level across both areas was particularly important.

Working with the builder, we established a target screed level 20mm below the new door threshold. This allowed for the planned tiled floor finish while creating one consistent level throughout the open-plan space.

The installation involved:

1. Checking the prepared floor and underfloor heating system prior to pouring.
2. Using laser equipment to establish accurate screed levels throughout the existing property and extension.
3. Setting the finished screed height 20mm below the new door threshold.
4. Pumping Cemfloor Therm C20 using our Putzmeister SP11 specialist screed pump.
5. Installing the liquid screed at varying depths of approximately 50mm to 90mm to compensate for differences in the underlying floor levels.
6. Dappling the freshly installed screed to produce a smooth, consistent finish across the complete 45m² area.

Despite the significant variation in screed depth, the liquid screed allowed the existing property and extension to be brought together at one consistent finished floor level.

The completed floor came out flat and level throughout the full open-plan area, successfully bringing the existing house and new extension together as one continuous space.

Most importantly, the finished screed level was exactly 20mm below the new door threshold, giving the builder the required allowance for the final tiled floor finish.

Cemfloor Therm C20 provided complete coverage around the underfloor heating pipes while allowing us to accommodate screed depths ranging from approximately 50mm to 90mm across the project.

The result was a smooth, accurately levelled floor ready for the next stage of the renovation.

If you’re building an extension, renovating your home or installing underfloor heating, Webster SRS provides professional liquid floor screeding throughout Bristol, Nailsea and North Somerset.

Using specialist pumping equipment and cement-based liquid screeds such as Cemfloor, we can create accurate, level floors across extensions, renovations and new-build projects.

Contact Webster SRS to discuss your floor screeding project or arrange a site visit.