Kerakoll Keracem Pronto ready-mixed screed for underfloor heating (CT-C30-F6)

Is your underfloor heating warming unevenly? The screed transfers heat from the pipes to the floor covering. If it conducts heat poorly, the system's efficiency decreases. Keracem Pronto has a thermal conductivity of 1.47 W/(m K). It is a ready-mixed product requiring only water. Ceramic tiles can be laid after 24 hours, and parquet after 5 days. This is Kerakoll Keracem Pronto.

• Underfloor-heated floor: thermal conductivity 1.47 W/(m K) — heat is distributed evenly, allowing the heating system to operate more efficiently
• The installer is waiting: on a 5 cm layer, ceramic tiles ≈ 24 hours, parquet ≈ 5 days — after 5 days, moisture content ≤ 2%
• Incorrectly proportioned on-site mix: ready to use, only clean water is required (≈ 1.7 l / 25 kg) — consistent performance from bag to bag
• Shop, office, busy communal area: CT-C30-F6 class, 28-day compressive strength ≥ 30 N/mm² — withstands heavy traffic
• Renovation, low installation height: bonded screed from just 20 mm, floating screed from 40 mm — fits even where there is little space up to floor level
• Cracking and movement beneath the floor covering: outstanding dimensional stability — a long-lasting, reliable base
• Terraces, balconies, frost-exposed areas: indoors and outdoors, even with significant temperature fluctuations — one screed for every floor in the home
• Any bonded floor covering: porcelain tiles in all sizes, stone, marble, parquet, PVC, rubber, linoleum, carpet — one substrate, many types of flooring
• Living areas, children's rooms: EC 1 plus and A+ indoor emissions classification — very low VOC emissions

What is it suitable for?

Screed: Bonded screed for floor coverings (bonded directly to the concrete) 20-80 mm; floating screed (laid on film or insulation) 40-80 mm; underfloor heating.

Floor coverings (with adhesive): Porcelain tiles and ceramic tiles in all sizes, clinker, terracotta, glass and ceramic mosaics; natural stone, composite stone, marble; parquet; rubber, PVC, linoleum, carpet.

Substrates: Precast or cast-in-place concrete slabs and bases; lightweight cement screed; thermal and acoustic insulation panels.

Areas: Indoors and outdoors — homes, shops, offices, industrial areas; also surfaces exposed to frost and large temperature fluctuations.

Not suitable for:

• On deformable substrates without flexural design calculations
• Without movement joints
• On concrete that has not fully cured, as a bonded screed
• For substrates subject to rising damp
• For layers thicker than 80 mm

The Kerakoll screed range

The screeds belong to the self-levelling compounds and screeds category. All five are mineral, fast-drying screeds for bonded coverings. The difference lies in strength, tiling time and application area.

*Keracem: 28-day compressive strength of 200 and 250 kg/m³ at the respective dosages. All times at +20 °C and 65% relative humidity.

Common to all: mineral, fast-drying screed for bonded coverings; also suitable for underfloor heating; EC 1 plus and A+ indoor emissions; moisture measurement only using the CM method.

Which screed do you need?

• Home renovation, ceramic tiles or parquet, normal load: Massetto Premix — easy-to-apply ready-mixed screed for normal loads
• Large area, own sand and mixer: Keracem — binder, dosage can be adjusted to the load
• Underfloor heating, any bonded covering, indoors and outdoors: Keracem Pronto — this is the product
• Cementoresina microcement, parquet after 3 days, heavy traffic: Keracem Prontoplus — fibre-reinforced, CT-C60-F7
• Tight deadline, indoors: Rekord Pronto — walkable after 3 hours, ceramic tiles after 6 hours

Layer structure for Keracem Pronto screed:

Frequently asked questions

What type of screed is needed for underfloor heating?
It has good thermal conductivity and is dimensionally stable. Keracem Pronto has a thermal conductivity of 1.47 W/(m K), ensuring even heat transfer to the floor covering. In a floating installation, it must be at least 40 mm thick.

How long before the screed can be covered?
On a 5 cm thick Keracem Pronto screed, ceramic tiles can be installed after ≈ 24 hours and parquet after ≈ 5 days. These times apply at +20 °C and 65% humidity. Drying takes longer in cold, humid weather.

When can the underfloor heating be switched on for the first time?
At least 5 days after laying. First, a flow temperature of +20–25 °C is required for 3 days, followed by at least 4 days at the planned maximum. Then return to room temperature, and the floor covering can be installed (EN 1264-4).

How much finished screed is needed per 1 m²?
≈ 16–18 kg per centimeter. For a 5 cm thick screed, ≈ 80–90 kg/m², i.e. 3.2–3.6 bags.

What does CT-C30-F6 mean?
CT denotes a cementitious screed according to the EN 13813 standard. C30 means a compressive strength of at least 30 N/mm², and F6 means a flexural strength of at least 6 N/mm².

How should I measure the screed's moisture before installing parquet?
Only with a calcium carbide (CM) meter. An electrical moisture meter gives fluctuating, unreliable readings for this screed.

What is the difference between Keracem Pronto and Prontoplus?
Prontoplus is fiber-reinforced and stronger (CT-C60-F7). Parquet can be installed after just 3 days, so it is recommended beneath Cementoresina. Pronto is a general-purpose screed, mainly for underfloor heating.

Is it suitable for outdoors and terraces too?
Yes, indoors and outdoors, including on surfaces exposed to frost. Outdoors, closer-spaced expansion joints are required: max. 35 m², with the longest side max. 7 m (floating screed on PE or PVC film).

When should I not use it?
Not on deformable substrates without bending calculations or without expansion joints. Nor as a bonded screed on concrete that has not fully cured. Do not add cement, sand, colorant, or additives.

Can I apply it myself?
A product intended for professionals. It requires level strips, thorough compaction, and precise expansion joints - it is best left to a professional. We also undertake the installation.