Types of Floor Screed

There are four main types of liquid floor screed used in UK construction today: anhydrite (calcium sulphate), Cemfloor (cement-based liquid screed), latex screed, and traditional sand-cement. Each has distinct applications, drying profiles, compressive strengths, and installation constraints. Choosing the wrong type costs time and money — choosing the right one delivers a flat, durable floor on programme. This guide covers what each type is, where to use it, and how to select the correct specification for your project in London and the South East.

What is Anhydrite Screed?

Anhydrite screed — also called calcium sulphate screed — uses a calcium sulphate binder in place of Portland cement. It is a self-levelling, self-compacting liquid screed that is pumped and laid flat without manual raking. In the UK, Gyvlon is the leading proprietary anhydrite product and the benchmark for this screed class.

Output rates reach 1,500m² per day, making it the fastest-laying screed available for large residential and commercial floors. It is fully compliant with EN 13813 (the European standard for screed material) and achieves a CT-C20-F4 strength class as standard, with enhanced grades available for higher-load applications.

Anhydrite performs exceptionally well over underfloor heating systems. Its self-compacting nature fully encapsulates UFH pipework with no voids, and it has a slightly higher thermal conductivity than cement-based alternatives — typically 1.5–2.0 W/mK versus 1.0–1.5 W/mK for sand-cement. Minimum installed depth is 30mm unbonded over insulation.

One critical limitation: anhydrite is not suitable for wet areas. Calcium sulphate is water-soluble, so bathrooms, wet rooms, and commercial kitchens require a different specification. The surface must also be sanded before any floor covering is applied to remove the laitance layer.

For full technical specifications, see our anhydrite screed service page.

What is Cemfloor Screed?

Cemfloor is a cement-based liquid screed — it delivers the same self-levelling, pumpable installation as anhydrite, but uses a cement binder. That single difference unlocks applications where anhydrite cannot go.

Because cement is not water-soluble, Cemfloor can be used in wet areas when installed with appropriate tanking. Bathrooms, wet rooms, commercial kitchens, and plant rooms are all viable. It achieves a CT-C25-F5 strength class — slightly higher than standard anhydrite — and carries the same EN 13813 compliance.

Output rates match anhydrite at up to 1,500m² per day for large pours, making it equally efficient on programme-critical sites. Like anhydrite, Cemfloor is fully compatible with underfloor heating systems and encapsulates pipework completely during the pour.

Cemfloor dries at the same rate as anhydrite — approximately 1mm per day up to 40mm depth under normal site conditions (20°C, 65% RH). Force drying from day 7 can accelerate this significantly. One practical advantage over anhydrite: no sanding of the surface laitance is required before laying floor coverings on Cemfloor.

See our Cemfloor screed service page for project examples and pricing guidance. For a full breakdown of pricing, see our liquid screed cost guide.

What is Latex Floor Screed?

Latex screed is a flexible, polymer-modified screed designed for thin-bed applications from as little as 3mm depth. It is the correct choice for refurbishment projects where every millimetre of floor-to-ceiling height matters — fitting a 30mm anhydrite pour into a Victorian conversion with low ceilings is often impossible; a 6mm latex application is not.

It bonds directly to existing substrates including concrete, timber, and existing tile beds, removing the need for a full separation membrane in most applications. This makes it significantly faster to install in occupied or partially occupied buildings. Most latex screeds achieve walkability within 2–4 hours and are ready for floor covering within 24 hours.

Latex screed is the preferred preparation layer for luxury vinyl tile (LVT) and ceramic tile installations, delivering the flat, stable, and slightly flexible surface these coverings require. It is equally effective as a patch repair medium on damaged or uneven existing floors.

It is not a structural screed — it does not replace a full screed pour in new-build or heavily loaded applications. For large, open-plan new builds, anhydrite or Cemfloor will always be more cost-effective and appropriate.

Full details on our latex screed service page.

What is Traditional Sand-Cement Screed?

Traditional sand-cement screed is the oldest method — mixed on site from cement and sharp sand (typically 1:3 to 1:4.5 ratio), applied manually, and finished by hand. It is still specified in some niche situations, particularly for repairs to existing sand-cement floors or where access constraints prevent pump equipment reaching the floor.

The limitations are significant. Drying times run to 28 days minimum for a 75mm pour — frequently longer on site. Surface flatness depends entirely on the operative’s skill level; inconsistent quality is common. It cannot self-level, so achieving the SR1 and SR2 surface regularity tolerances required for modern floor coverings often requires significant remedial grinding.

For any project where programme, quality, and floor covering compatibility are priorities, sand-cement screed has been largely superseded by liquid screeds. London Flow Screed does not install traditional sand-cement — it is included here for comparison purposes only.

Anhydrite vs Cemfloor — Which Should I Use?

This is the most common specification question we receive. The decision comes down to three factors: wet area exposure, strength requirement, and surface finish protocol.

In practice: if your project contains any wet areas, specify Cemfloor throughout for simplicity and consistency. If the entire floor is dry and you have anhydrite experience on site, anhydrite is equally valid and delivers marginally better thermal performance over UFH.

Both are categorically superior to sand-cement on any programme-critical project. For full strength data and installation specs, see our technical data page.

Which Screed Type is Best for Underfloor Heating?

Both anhydrite and Cemfloor are fully compatible with underfloor heating and are the correct specification for UFH installations. Sand-cement screed over UFH is a poor choice — the inconsistent pour density creates thermal bridging around pipework, reducing system efficiency.

Anhydrite holds a slight thermal conductivity advantage: 1.5–2.0 W/mK versus approximately 1.0–1.5 W/mK for cement-based liquid screeds. In practice, on a well-designed UFH system the difference is measurable but not decisive — both fully encapsulate pipework with no voids, which is the most critical factor for heat transfer and pipe protection.

The commissioning protocol is identical for both types. Heat-up must not begin before day 7 after pouring. Start at 25°C flow temperature and increase by 5°C per day to maximum operating temperature. This gradual ramp prevents thermal shock cracking across the full screed area. Document the heat-up log — it is required by most floor covering manufacturers’ warranties.

Latex screed is not recommended as the primary screed layer over UFH due to its shallow depth — it does not provide adequate thermal mass. It can be used as a topping coat over a cured liquid screed base if needed.

Full commissioning guidance on our underfloor heating guide.

Which Screed Type Dries Fastest?

All liquid screeds — anhydrite, Cemfloor, and latex — dry significantly faster than traditional sand-cement. The key figures:

• Anhydrite and Cemfloor: approximately 1mm per day up to 40mm depth under ambient conditions (20°C, 65% RH). A 40mm pour is typically dry in 40 days naturally.
• Force drying: from day 7, dehumidifiers and underfloor heating can be activated. This can reduce total drying time to 50–60% of natural drying time for a 40mm pour.
• Latex screed: walkable in 2–4 hours; ready for floor coverings in 24 hours for most thin-bed applications. Fastest of all types for refurbishment overlays.
• Sand-cement: 1 day per millimetre minimum — a 75mm structural screed requires 75 days. No reliable acceleration method.

Programme planning note: always specify liquid screed and factor in force drying from day 7 if the project is on a tight handover schedule. Waiting 75 days for sand-cement to cure on a commercial fit-out is not a schedule most contractors can absorb.

See our complete floor screed drying times guide for drying charts by pour depth and ambient condition.

How Do I Prepare My Floor for Any Type of Screed?

Correct substrate preparation is the single most common point of failure in screed installations. Regardless of screed type, the following requirements apply:

• Clean substrate: remove all dust, grease, paint, laitance, and debris. Contamination prevents proper adhesion and creates delamination risk under liquid screeds.
• Separation membrane or insulation layer: for unbonded and floating applications, a polythene DPM (minimum 500 gauge) or rigid insulation board must be laid before the screed pour. Laps must be taped.
• Expansion strips: perimeter foam edging strips are essential for all liquid screeds. They accommodate thermal expansion and prevent cracking at walls, columns, and door thresholds. Bay joints are required for pours exceeding 40m in any direction.
• Level check: survey the substrate with a 3m straightedge before pouring. Variations greater than ±5mm require correction before the screed is applied.

Full substrate requirements by screed type are covered in our floor preparation guide.

Which Type of Screed Does London Flow Screed Install?

London Flow Screed installs all three liquid screed types: anhydrite, Cemfloor, and latex. We also carry out polished concrete finishing as a standalone service.

We cover London across all 32 boroughs and 12 counties across the South East — including Kent, Surrey, Essex, Hertfordshire, Berkshire, Buckinghamshire, Oxfordshire, East Sussex, West Sussex, Hampshire, Bedfordshire, and Cambridgeshire. Our pump rigs can reach projects from central London to the M25 corridor and beyond on the same-day mobilisation for contracts over 500m².

All projects receive a free no-obligation quote. We specify the correct screed type for your project based on floor use, UFH system, floor covering specification, and programme requirements — not on what is easiest to lay.

Call us on 07730 584 748 or submit a project enquiry here and we will respond within one working day.