Schlüter-DITRA-HEAT-DUO is a polypropylene membrane with a cut-back stud structure and a special 2 mm anchoring fleece laminated on the underside. In addition to bonding with the tile adhesive, the material reduces impact sound and ensures a quicker heat up response.

It is a universal substrate for tile coverings that forms an uncoupling, crack bridging, waterproofing and vapour pressure equalisation layer and can also be used to attach heating cables.

The substrate for the installation of DITRA-HEAT-DUO must be level and load bearing. DITRA-HEAT-DUO is installed in thin-bed tile adhesive that is suitable for the substrate, using a notched trowel (recommended size: 6 x 6 mm). The anchoring fleece on the underside of DITRA-HEAT-DUO is fully embedded and the fabric bonds with the adhesive. The curing time of the adhesive must be observed.

In floor areas, the heating cables can be installed immediately after adhering DITRA-HEAT-DUO, using a minimum spacing of 9 cm (every third stud ≙ 136 W/m²).

For wall installation, the heating cables are installed once an adequate adhesive bond has been reached. The installation spacing is either 6 cm (every second stud ≙ 200 W/m²) or 9 cm (every third stud ≙ 136 W/m²). The use of mats is recommended for wall areas.

The tile or stone covering is installed directly over DITRA-HEAT-DUO in accordance with the applicable standards, using the thin-bed method. The thin-bed tile adhesive bonds with the cutback stud structure of the DITRA-HEAT-DUO membrane.

DITRA-HEAT-DUO is waterproof and resistant to any chemical stresses that typically occur in conjunction with tiled coverings. Where required, DITRA-HEAT-DUO can be used to create a certified bonded waterproofing assembly.

Use the cable tester Schlüter-DITRA-HEAT-E-CT to measure the resistance of the electrical heating cables DITRA-HEAT-E-HK and the remote sensors supplied with DITRA-HEAT-E thermostats. The testing device monitors the resistance of the heating cables during the entire installation phase and alerts the installer with an acoustic signal in the event of damage. The cable tester automatically shuts down 60 minutes after the last key activation (values will not be saved).

Summary of functions

a) Uncoupling

Schlüter-DITRA-HEAT-DUO uncouples the covering from the substrate and neutralises stresses between the substrate and the tile or stone covering that result from various deformations. It also bridges tension cracks from the substrate and prevent them from affecting the tile covering.

b) Waterproofing

Schlüter-DITRA-HEAT-DUO is a waterproof polypropylene membrane with a relatively high water vapour diffusion seal. With properly installed abutting joints and carefully sealed transitions to walls and structural elements, DITRA-HEAT-DUO can be used to create a certified bonded waterproofing assembly with the tile covering.

DITRA-HEAT-DUO can be installed in accordance with the waterproofing standard DIN 18534 applicable in Germany. Water exposure classes: W0-I to W3-I. DITRA-HEAT-DUO also features the national technical approval (abP) required in Germany.

Moisture load class according to ZDB: 0 to B0, as well as A.

DITRA-HEAT-DUO has a European Technical Assessment (ETA) pursuant to ETAG 022 (watertight covering kits) and bears a CE mark.

System-certified tile adhesives must be used in areas that require CE-compliance or assemblies according to abP (certificate of technical approval). Please contact us using the details listed at the bottom of this page for further information about such tile adhesive products and the corresponding certificates of technical approval.

DITRA-HEAT-DUO effectively protects the sub-structure from damage caused by permeating moisture or aggressive substances.

c) Load distribution (load induction)

Tiles installed over Schlüter-DITRA-HEAT-DUO in floor areas should have a minimum size of 5 x 5 cm and a thickness of at least 5.5 mm. The adhesive-filled, square recesses of DITRA-HEAT-DUO transfer mechanical stresses impacting the tile covering directly to the substrate. This makes tile coverings installed on DITRA-HEAT-DUO especially durable. The tiles for the corresponding application area must be sufficiently thick and have adequate compressive stability to withstand high traffic loads (e.g. in commercial areas) or large point loads (such as concert pianos, forklifts, or shelf systems). In Germany, the guidelines of the ZDB information sheet “Ceramic floor coverings for high mechanical impact” must be observed for tile thicknesses.

Tiles in high-stress areas must be fully embedded in the tile adhesive.

DITRA-HEAT-DUO, with its special 2 mm anchoring fleece laminated on the underside, is suitable for traffic loads of up to 3 kN/m². This includes residential and commercial premises with light foot traffic (private homes, office and administrative spaces, restaurants, hotels, conference rooms, nursing stations and patient rooms etc.).

The impact of hard objects must be avoided on ceramic coverings installed over DITRA-HEAT-DUO. The tile dimensions should be at least 5 x 5 cm.

d) Bonded assembly

Based on the fleece fabric bond in the thin-set adhesive on the substrate, and through mechanical anchoring of the thin-set adhesive in the cut-back stud structure, Schlüter-DITRA-HEAT-DUO creates a strong bond between the tile assembly and the substrate. That makes DITRA-HEAT-DUO suitable for both wall and floor installation.

e) Thermal separation

Schlüter-DITRA-HEAT-DUO has a special 2 mm anchoring fleece laminated on the underside. In addition to bonding with the tile adhesive, the material reduces impact sound and ensures a quicker heat-up response.

f) Sound insulation

An impact sound improvement value (ΔLW) of 13 dB was measured (according to DIN EN ISO 10140) in fully installed Schlüter-DITRA-HEAT-DUO assemblies.

The actual improvement offered by the respective assembly depends on the local conditions (structural design) and can deviate from this value. The measured test values therefore don't apply equally to every building situation.

Further information on each of the set components can be found on their respective pages or in the installation instructions - see the Downloads tab.

Schlüter-DITRA-HEAT-DUO is a polypropylene membrane with a cut back stud structure and imprinted EasyCut gridlines. A fleece fabric is laminated on the underside. The product thickness, including the stud structure, is approx. 7.5 mm.

Polypropylene is not UV-stable in the long term; the product should not be stored in places with prolonged exposure to direct sunlight.

Material properties and areas of application

Schlüter-DITRA-HEAT-DUO is non-rotting, waterproof, stretchable and crack-bridging. In addition, it is largely resistant to the effects of aqueous solutions, salts, acids and alkalis, many organic solvents, alcohols and oils.

Product resistance to special local conditions must be verified separately based on the anticipated concentration, temperature and length of exposure. The product has a relatively high water vapour diffusion seal. The material is non toxic and physiologically harmless.

Product suitability must be verified in applications exposed to chemical or mechanical stresses. The information provided on this page is intended as a general guideline.

Depending on the system, stepping on coverings installed over DITRA-HEAT-DUO with hard shoes or tapping them with a hard object may produce a hollow sound.

The use of DITRA-HEAT-DUO in conjunction with heating cables as a floor/wall heating system is only permitted for interior areas.