Kiilto Floor Heat DF
Levelling screed for floor heating

A dust reduced and fibre-reinforced levelling compound for building of floor slopes in floors with underfloor heating. Compatible with both warm water tubing and electric cables. Also suitable for general floor levelling. Low-alkali.

Special features

  • dust reduced, fibre-reinforced, multi-purpose
  • ideal for underfloor heating floors and building of floor slopes, general levellings
  • coverage 1.7 kg/m²/mm
  • walkable: 1 h
  • coatable: 30 mm /1–2 d, 50 mm/3 d
  • interior areas




A levelling compound containing reinforcing fibres for floors with underfloor heating. Suitable for warm water tubing and electric cables.

The substrate must be clean and solid. Remove cement laitance, paint splashes, adhesive residue and other impurities, and vacuum the floor thoroughly. When installing underfloor heating, ensure that the substrate is solid enough to resist thermionic movements.

Concrete subfloors are pre-treated with 1:4 diluted Kiilto Start Primer or PrimerOne (20% Kiilto primer/80% water) prior to application of the floor screed. Surfaces under construction as well as board surfaces must be primed with undiluted Kiilto Start Primer or PrimerOne before levelling. Non-absorbent substrates, such as ceramic tiles or painted surfaces can also be treated with Kiilto Fix Primer.

In underfloor heating floors, the subfloor must be sanded and cleaned properly prior to primer and levelling compound to ensure proper adhesion.

Underfloor heating tubing/cables must be installed according to the manufacturer's instructions on a dried primer/bond layer. After that continue with the levelling.

A low alkaline screed layer protects the adhesive and vinyl coating from the damage caused by alkaline moisture in the concrete. The studies have shown that a 5 mm thick screed layer provides the protective effect.

The concrete substrate must comply with national standards.

Package Size EAN Code
20 kg 6411512001203
Application temperature

Optimal +18–23 °C, minimum +10 °C

Bond strength

> 1.5 MPa, EN 13813

Classifications and certificates

CT-C30-F7 (EN13813), M1


1-2 d / 30 mm
approx. 3 d / 50 mm
( 23 ºC, 50 % RH )

Compression strength

C30 (> 30 MPa), EN 13813


1 mm layer/m² solid matter weighs approx. 1.7 kg (approx. 12 litres of screed/bag).

Fire class


Flexural strength

F7 (> 7 MPa), EN 13813

Layer thickness

3–50 mm

Max. grain size

approx. 1 mm

Mixing ratio

approx. 3.0 litres water / 20 kg bag (slopes)
approx. 3.7 litres water / 20 kg bag (overall levellings)

Package sizes

20 kg bag


< 0.4 ‰ (23 °C, 50 % RH)


Unopened package in a dry place 1 year.

Substrate humidity

Concrete < 90 % RH


Fibre-polymer-special cement-quartz-based powder


Flow rate 125–135 mm (EN 12706)


1–3 h ( 23 ºC, 50 % RH )

Working time

approx. 20 min ( 23 ºC, 50 % RH )


< 11 (low alkali)

Instructions for use

Fill the mixing container with the required amount of clean water. Strew powder slowly while stirring in cool (+10–25 °C), clean water until a smooth flexible mass is formed. Let the mix mature for approx. 2 min. and then remix once before use.

Apply screed by using a steel trowel. Ensure that during the levelling work the floor heating cables/cable mat/tubing are properly embedded in the floor screed so that the heat will be distributed evenly and a proper bond is built between the floor screed and subfloor. The screed layer must be dry before a new layer is applied.

The drying of the screed must not be accelerated by heat or ventilation, since too quick a drying may cause hair cracks. If the temperature in the levelled room is higher than normal, the relative humidity very low, or if the levelled floor surface is exposed to direct sunlight, we recommend covering the floor with a tarpaulin or treating it with Kiilto 704 BSP Jälkihoitoaine agent as soon as it is dry enough to allow walking. The floor should be covered with a flooring relatively soon after it has hardened and dried. This will prevent the surface from over drying, cracking and becoming loose.

The surface temperature of underfloor heating floors must not exceed +28 °C.

With larger surfaces consider the need for movement joints (wall – floor joints, inlets; in elongated spaces (relation between sides over 2:1) movement joints at 5 metre intervals, division of larger areas to smaller sections, etc.).

In optimal drying conditions (20 ºC, 50% RH), the floor covering can be installed after 1–3 days depending on the thickness of the screed. The screed will soon acquire good surface strength and will chemically absorb the amount of water defined in the instructions. Substrate's high moisture content and poor drying conditions will lengthen the drying time. Follow the floor covering manufacturer's requirements as well as the national requirements on substrate moisture content. Consider the entire floor construction when assessing the floor's suitability for covering.

Suitable also for floors that are going to be painted in secondary rooms with light traffic, but not, for example, in garages or for bathroom floors, etc. In areas where waterproofing is used, e.g., bathroom floors, floor levelling should be applied under the waterproofing membrane. In floor heating floors in dry areas waterproofing membrane can be installed between the levelling and tiling where it works as a suppressant layer against tensions coming from the substrate.

Not suitable for areas permanently under water (e.g., swimming pools).

Note! Avoid excessive use of water, since it will weaken the surface strength and may cause separation and cracking.

Additional information

The information given in this product data sheet is based on our tests and our practical knowledge. The technical data is defined in standard conditions. Variations in local working conditions and methods will affect the product performance and result. We guarantee the high quality of our products according to our Quality Management System. No liability can be accepted from incorrect use of the product or prevailing conditions, over which we have no control. Thus, we cannot be held responsible for the final result. The correct use of the product presupposes that the user has made him/herself aware of the contents of the working instructions and procedure guide, if provided.

Environment and safety

Avoid unnecessary skin contact and exposure with the fresh product, use safety gloves. Refer to material safety data sheet. For information on product and package disposal, go to