Cementitious flow screed (CTF)
Cementitious flow screed (CTF) - efficiency and precision for modern floor constructions
Cementitious self-levelling screed (CTF) in accordance with DIN EN 13813 represents the modern evolution in screed construction. Its outstanding property is its self-levelling consistency, which enables fast installation and exceptionally high evenness. These features, combined with the proven robustness of cementitious systems, make CTF the technically superior and economical solution for numerous demanding applications in new builds and renovations. As your specialist company for screed work, we master the planning, material selection and precise execution of cement flow screeds at the highest level - a core competence that we use for your project.
Composition and innovative material properties
Cement screed is based on a mineral screed mortar, the performance of which depends crucially on the quality of the raw materials and the exact formulation. Usually supplied as factory premixed dry mortar, this guarantees consistently high and tested quality. The main ingredients are
- Binder: Standardized cement (according to DIN EN 197-1), responsible for strength development and durability.
- Aggregate: Carefully selected sands and gravels (in accordance with DIN EN 12620) with optimized grading curve for a dense, stable structure despite a free-flowing consistency.
- Mixing water: Precisely dosed to set the desired flowability and to control hydration. The water/cement ratio (w/c ratio) is a critical quality parameter that is set at the factory.
- Superplasticizer: Indispensable chemical additives that enable the mortar to liquefy at a constant water content and thus create the self-levelling properties in the first place.
- Other additives/substances(optional): Used specifically to fine-tune properties such as processing time, recovery, shrinkage behavior or to meet specific requirements (e.g. early strength, fiber reinforcement).
Curing takes place through the chemical reaction of the cement with water (hydration), which leads to a firm, highly resilient screed structure. In addition to high compressive and flexural strength, CTF is characterized by excellent evenness and insensitivity to moisture after complete drying out.
Wide range of applications for cement self-levelling screed
The special processing properties and technical characteristics predestine CTF for a wide range of construction projects:
- Residential construction: Ideal solution for single and multi-family homes, especially for large areas or high demands on evenness (e.g. under large-format tiles or parquet).
- Commercial and industrial construction: Efficient installation in large areas in offices, sales rooms, storage areas or workshops. Selecting the right strength class is essential for this.
- Public buildings: Fast and precise screed laying in schools, hospitals and administrative buildings.
- Damp rooms: Once completely dry and in combination with standard-compliant bonded waterproofing, ideally suited for bathrooms, kitchens and wellness areas.
- Heated floor constructions: As a heating screed, CTF enables particularly good enclosure of the heating pipes, which contributes to efficient heat dissipation of the underfloor heating.
- Renovation: Ideal for leveling uneven substrates or for limited construction heights (depending on the specific product formulation and static specifications).
- Universal substrate: Compatible with all common floor coverings once ready for covering and any necessary substrate preparation (e.g. sanding).
Decisive advantages of cement self-levelling screed
- 🚀 High installation performance: Significantly faster installation compared to conventional screed thanks to pumpability and self-leveling properties.
- 📐 Excellent evenness: Easily achieves the highest evenness requirements in accordance with DIN 18202, ideal for modern floor coverings.
- 💧 Moisture resistance: Permanently resistant to moisture after drying out (note residual moisture!).
- 💪 High strength: Offers excellent compressive and flexural tensile strength for various load requirements.
- 🌡️ Optimum heat conduction: Very suitable for underfloor heating systems thanks to tight pipe surrounds.
- 🏗️ Lower installation heights possible: Depending on the system and static requirements, lower nominal thicknesses can be realized in some cases.
- 💶 Cost-effectiveness: High area output and reduced labor costs can often compensate for the additional material costs.
- 🔥 F ire protection: As a non-combustible building material (class A1), it meets the highest fire protection requirements.
- ⏳ Durability: professionally installed, it forms a solid and durable basis for decades.
Technical properties and classification according to DIN EN 13813
As with conventional cement screed, the performance of a cement flow screed is classified by its compressive strength (C = Compressive Strength) and flexural strength (F = Flexural Strength): CTF-C[Wert]-F[Wert].
- CTF: Cementitious self-levelling screed
- C[value]: Characteristic value of the compressive strength class (e.g. C25 for )
- F[value]: Characteristic value of the bending tensile strength class (e.g. F5 for )
The selection of the standard-compliant strength class depends on the expected use and load and is a central component of planning.
Overview of common strength classes:
ℹ️ Note: Correct dimensioning and determination of the screed class is crucial for functionality and durability. It should be carried out by qualified planners or in consultation with the specialist company carrying out the work.
Processing and decisive drying phase
The quality of the finished cement flow screed depends to a large extent on compliance with the specific processing steps:
- Substrate inspection and preparation: Cleanliness, evenness, load-bearing capacity and any necessary primers are essential. Edge insulation strips must be laid precisely.
- Mixing: Usually carried out in a screed mixer or silo with a compulsory mixer, strictly adhering to the specified amount of water to achieve the correct flow consistency.
- Pumping and application: The liquid mortar is pumped onto the prepared surface.
- Spreading and leveling: Using special squeegees or buffing rods, the mortar is spread evenly and brought to the exact height. The material is largely self-leveling.
- Deaerate (if necessary): With some systems, it may be advisable to work lightly with a spiked roller to bleed the air.
- Controlled post-treatment/protection: It is crucial to protect the surface from drying out too quickly (draughts, direct sunlight, excessively high temperatures) in the first few days in order to prevent cracking and ensure optimum strength.
The drying time to readiness for covering is a critical factor ❌ as with any cementitious screed and must not be underestimated. It is influenced by:
- Screed thickness (decisive factor)
- Ambient climate (temperature, humidity)
- Air change
- Cement type and specific formulation (admixture)
Rules of thumb are unreliable! ⚠️ The floor may only be approved for covering once the residual moisture required by the standard has been reached. This can only be reliably verified by a professional CM moisture measurement. Laying too early almost always leads to serious damage to the floor covering and screed construction (e.g. detachment, mold growth). In the case of flowing screeds, surface preparation (sanding) may also be necessary to remove any fine surface layers or sintered skins that may have formed and to ensure optimum adhesion of the subsequent covering.
Construction variants for cement flowing screed
Due to its processing properties, CTF is primarily used as:
- Floating screed (screed on an insulating layer): The most common application, ideal for thermal and impact sound insulation in building construction.
- Heating screed: A floating screed that accommodates and optimally encloses the pipes of an underfloor heating system.
- Screed on separating layer: Allows movement relative to the substrate.
- Bonded screed: Technically possible, but requires very careful substrate preparation (bonding bridge) and is used less frequently than with conventional CT.
- Rapid screed variants: Also available as CTF, with special binders or additives for accelerated drying and earlier readiness for covering.
Professional execution - our quality promise
The outstanding properties of cement self-levelling floor screed can only be fully exploited with perfect craftsmanship and the use of tested materials. Our quality standards are based on:
- Strict compliance with standards: Compliance with all relevant standards and regulations (DIN 18560, DIN EN 13813, DIN 18202, BEB data sheets).
- Tested material quality: use of high-quality, quality-monitored ready-mixed dry mortar.
- Precise processing: mastery of pumping and leveling techniques, consistency control.
- Guaranteed evenness: Ensuring the required evenness tolerances as a perfect base for the top layer.
- Careful post-treatment: protection of the young screed for optimum curing.
- Responsible moisture measurement: Professional implementation and documentation of CM measurement to determine readiness for covering.
- Necessary surface preparation: Professional sanding, if necessary.
Commissioning our specialist company ensures that your cement flow screed meets these high quality standards - for an efficient, high-precision and durable floor structure.
Frequently asked questions (FAQ)
No. It can often be walked on more quickly, but the drying time until it is ready for covering is generally not shorter. It depends on the thickness, climate and ventilation. The CM measurement to determine the residual moisture is crucial and absolutely essential.
Yes, absolutely. It can achieve the same high strength classes (e.g. CT-C25-F4, CT-C30-F5 etc.) as conventionally installed cement screed if it is manufactured and processed professionally.
Yes, very good. Thanks to its flowable consistency, it encloses the heating pipes well, which supports efficient heat transfer. It forms a solid heating screed.
The pure material costs can be slightly higher than for standard cement screed. However, due to the faster installation (less working time), the total cost per square meter can often be comparable or even lower, especially for larger areas. An individual quotation is required.
Yes, as with any flowing screed, it must be clean, load-bearing and, above all, absolutely tight at all edges and penetrations (foils/sealings must be correctly raised and bonded) so that the liquid screed cannot leak out in an uncontrolled manner.