Schlüter-DITRA-HEAT  Uncoupling mat designed for attaching heating cables

Would you like electrical heating in your living room or are you planning to retrofit a floor heating system over an existing screed or wood structure? In addition to the proven functions of Schlüter-DITRA (uncoupling, bonded waterproofing and vapour pressure equalisation), Schlüter-DITRA-HEAT with its special stud structure also enables the installation of electrical heating cables. DITRA-HEAT is therefore not just an ideal substrate for ceramic tiles and natural stone, but also an innovative heating electrical heating system for floor and wall areas.

Product image DITRA-HEAT 1©Schlüter-Systems KG
Product image DITRA-HEAT 2©Schlüter-Systems KG
Product image DITRA-HEAT 3©Schlüter-Systems KG
Product image DITRA-HEAT 4©Schlüter-Systems KG
Cross-section drawing DITRA-HEAT 1©Schlüter-Systems KG
zoom_out_map search
Product image DITRA-HEAT 1
Product image DITRA-HEAT 2
Product image DITRA-HEAT 3
Product image DITRA-HEAT 4
Cross-section drawing DITRA-HEAT 1

General product information

What this product does

Schlüter-DITRA-HEAT is a polypropylene membrane with a cut back stud structure and an anchoring fleece laminated on the underside.

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

The substrate for the installation of DITRA-HEAT must be level and load bearing. DITRA-HEAT 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 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, using a minimum spacing of 9 cm (every 3rd stud).

For wall installation, the heating cables are installed once an adequate adhesive bond has been reached. The installation spacing is either 6 cm (every 2nd stud) or 9 cm (every 3rd stud) (for more information, see data sheet 6.4 on page 7, see Downloads).

The use of mats is recommended for wall assemblies.

The tiles are installed directly over DITRA-HEAT in accordance with the applicable regulations, using the thin-bed method. The thin-bed tile adhesive bonds with the cut-back stud structure of the DITRA-HEAT membrane.

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


Summary of functions:

a) Uncoupling

DITRA-HEAT uncouples the covering from the substrate and neutralises stresses between the substrate and the tile covering that result from various deformations. The material also bridge tension cracks from the substrate and prevent them from affecting the tile covering.

b) Waterproofing

DITRA-HEAT 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 can be used to create a certified bonded waterproofing assembly with the tile covering.

DITRA-HEAT can be installed in accordance with the waterproofing standard DIN 18534 applicable in Germany. Water exposure classes: W0-I to W3-I*. DITRA-HEAT 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 has a European Technical Assessment (ETA) in accordance with 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 at the address listed in this data sheet for further information about such tile adhesive products and the corresponding certificates of technical approval.

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

* With abP and/or in compliance with ETA according to ETAG 022. Our Technical Department will be pleased to provide information on use and installation on request.

c) Load distribution (load induction)

Tiles installed over DITRA-HEAT in floor areas should have a minimum size of 5 x 5 cm and a thickness of at least 5.5 mm. DITRA-HEAT transfers mechanical stresses impacting the tile covering directly into the substrate via the bottom of the recesses, which are filled with thin-bed mortar. That makes tile coverings installed on DITRA-HEAT 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). The information and tile thicknesses specified in the ZDB information sheet "Ceramic floor coverings with high mechanical stress resistance", valid in Germany, must be observed.

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

The impact of hard objects must be avoided on ceramic coverings. The tile dimensions should be at least 5 x 5 cm.

d) Bonded assembly

Based on the fleece fabric bond in the thin-bed mortar on the substrate, and through mechanical anchoring of the thin-bed mortar in the undercut stud structure, DITRA-HEAT creates a strong bond between the tile assembly and the substrate. This makes DITRA-HEAT suitable for wall and floor installation.


Substrates for Schlüter-DITRA-HEAT

Always check that the substrates on which DITRA-HEAT is to be installed are level, load bearing, clean and compatible with the materials to be used. Remove all surface components that may weaken the bond. Any levelling, height adjustment or slope compensation must be carried out before installing DITRA-HEAT.

To guarantee effective floor heating, heat insulation is required, especially for installations adjoining soil or unheated spaces.

For a faster heat-up response on unheated screed assemblies, we recommend using DITRA-HEAT-DUO for its thermal separation function or Schlüter-KERDI-BOARD as an insulation layer (see data sheet 12.1).


Concrete undergoes long-term structural deformation due to shrinkage. In addition, tension can build up in concrete and pre-stressed concrete due to deflection.

Since DITRA-HEAT absorbs the resulting stresses between the concrete and the tile covering, tiles can be immediately installed as soon as the concrete is ready to bear weight.

Cement screeds

In accordance with the applicable regulations, cement screeds must have cured for a minimum of 28 days prior to tile installation and have a moisture content below 2 CM %.

Floating and heated screeds have a particular tendency to buckle and crack even later, e.g. due to mechanical stresses and temperature fluctuations. With DITRA-HEAT, tiles can be installed on green cement screeds as soon as they are ready to bear weight.

DITRA-HEAT will neutralise cracks and screed deformations developing later and will prevent them from affecting the tile covering.

Gypsum based screeds

According to the applicable regulations, calcium sulphate screeds (anhydrite) may not have a residual moisture level of more than 0.5 CM % at the time of tile installation. In contrast, tile installation is permissible from a residual moisture level of 2 CM % with DITRA-HEAT.

If necessary, the screed surface must be treated (grinding, priming) as specified by the applicable technical regulations and manufacturer instructions. DITRA-HEAT can be installed with dry-setting or other suitable thin-bed tile adhesives. DITRA-HEAT protects the screed surface against permeating moisture. Because gypsum based screeds are susceptible to moisture, screeds must be protected against humidity, e.g. moisture seepage on the underside.

Heated screeds

DITRA-HEAT can be used on heated screeds, provided the above notes (cement, gypsum based screeds) are followed. Covering assemblies created with DITRA-HEAT are ready for heating only 7 days after completion. Starting from a temperature of 25 degrees C, the supply temperature can be increased by no more than 5 degrees C a day to a maximum of 40 degrees C.

Note: Installing DITRA-HEAT over heated screeds makes it possible to operate an individual, partial heating system that is independent of the central heating system. This allows for completely turning off the central heating system during seasonal transition times.

DITRA-HEAT assemblies can also cover peak loads.

(Due to the thermal separation properties of the product, DITRA-HEAT-DUO should not be installed over heated screeds.)

Vinyl coverings and coatings

All surfaces must be load bearing and pre-treated or suitable for bonding with an appropriate adhesive, in which the DITRA-HEAT anchoring fleece can be embedded. The compatibility of the adhesive with the substrate and with DITRA-HEAT must be verified in advance.

Chipboard and compressed wood panels

These materials undergo significant deformation based on the influence of moisture (or through fluctuations in humidity). Therefore, chipboard and compressed wood panels with special water-repellent treatment to protect against moisture must be used.

Such panels can generally be used as a floor and wall substrate in interior spaces. Refer to local regulations if these are acceptable.

However, they have to be thick enough to be sufficiently stable in conjunction with a suitable support assembly.

The structure should be fastened with closely spaced screws. All joints should either have a tongue and groove connection or covered with adhesive. Perimeter movement joints of about 10 mm have to be maintained at the transition to upright building structures.

DITRA-HEAT neutralises any tensions with the tile covering and also prevents permeating moisture.

Hardwood floors

In principle, ceramic coverings can be installed on sufficiently weight bearing hardwood floors with tongue and groove connections. The wooden substrate should have balanced moisture levels before DITRA-HEAT can be installed.

It has proven beneficial to install an additional layer of chipboard or compressed wood panels. Uneven floor surfaces should be levelled with suitable measures beforehand.

Masonry / mixed substrates

Masonry structures built with bricks, sand lime bricks, cement blocks, aerated concrete or similar materials are generally a suitable substrate for DITRA-HEAT. The substrate must be levelled in advance.

In restoration and remodeling projects, substrates frequently consist of different materials (mixed masonry), which have a tendency to crack at the interfaces with other materials due to different deformation rates. DITRA-HEAT protects the tile covering from the resulting tensions and cracks.

Gypsum plaster / bricks

Gypsum substrates should be completely dry in accordance with the relevant regulations. The surfaces may need to be pre-treated with a primer. DITRA-HEAT can be installed with dry-setting or other suitable thin-bed tile adhesives.

How to install this product

  1. The substrate must be free of components that may inhibit bonding, load bearing and level. Any necessary levelling work must be completed before installing DITRA-HEAT.
  2. The selection of the adhesive for installing DITRA-HEAT depends on the substrate.

    The adhesive must bond with the substrate and mechanically attach to the DITRA-HEAT anchoring fleece. A dry setting thin-bed tile adhesive is suitable for most substrates. The adhesive should preferably have a consistency suitable for fluid beds. Review any potential material incompatibilities beforehand. If using covering materials with a side length exceeding 30 cm, we recommend a water-binding tile adhesive for rapid curing and drying.
  3. Apply a suitable thin-bed tile adhesive on the substrate with a notched trowel (6 x 6 mm). To achieve better initial adhesion for installation in wall areas, we recommend applying a contact layer on the underside of DITRA-HEAT.
  4. Embed the DITRA-HEAT mats, which must have been cut to size beforehand, into the installed adhesive, the anchoring fleece facing down, and immediately press them in place with a float or roller, working in a single direction. The curing time of the adhesive must be observed. For efficient installation of product rolls, precisely align DITRA-HEAT and keep the material tightly stretched with light tension when placing it on the substrate.

    The EasyCut gridlines minimise the curling memory. Mats are recommended for wall applications for easier handling. The mats or membranes are installed with closely abutting joints.
  5. To prevent any damage to the installed DITRA-HEAT material or detachment from the substrate, protect the area from mechanical stresses, e.g. by setting out running boards (particularly in the centre areas used for material transport).

    Installation of electrical Schlüter-DITRA-HEAT-E components (follow data sheet 6.6)

    Heating cable installation
  6. For installation in floor areas, heating cables may be installed immediately after adhering the uncoupling mat DITRA-HEAT, using a float or roller.

    For wall installation, the heating cables are installed once an adequate adhesive bond has been reached.

    Heating cables must never overlap or touch each other.
  7. Create a corresponding indentation in the area of the sealed cable end.

    Note: Before embedding the sensors with thin-bed mortar, measure the resistance values, e.g. with the cable tester Schlüter-DITRA-HEAT-E-CT, and compare them with the values listed in the thermostat installation instructions.
  8. The transition from the heating cable to the connection pipe (fitting) is marked with an imprint as shown. The fitting also bears a sticker that reads "Übergang/Connection". The connection pipe is labelled with the imprinted marking "COLD" further on. This cold conductor (4 m) must be installed directly in a junction box or connected to the thermostat. The cold conductor may be shortened to a max. length of 1.00 m before the fitting. The heating cables may not be shortened.

    The electrical installation must be performed by a qualified electrician (EN 60335-1).

    Note: Further information on installing the temperature sensor, heating cables and installing and setting up the thermostat can be found in the respective installation instructions included with the heating cable or thermostat, or the data sheet 6.6 Schlüter-DITRA-HEAT-E.

    Installation on ceramic coverings:
  9. After installing and checking the heating cables as specified in the installation instructions for DITRA-HEAT-E, the tiles can be installed in the thin-set method, using a thin-bed tile adhesive that meets the requirements of the respective covering. For maximum efficiency, fill the indentations of the heating mat with the smooth side of a notched trowel (heating cable and fittings must be completely embedded within the tile adhesive) and groove the thin-bed tile adhesive with the notched side of the trowel to prepare for tile installation. The notch size of the trowel must match the tile size to completely embed the tiles in the thin-bed tile adhesive. Observe the curing time of the adhesive.
  10. Follow the instructions in this data sheet to install movement joints for perimeter, edge and transition profiles.

Note: The thin-bed mortar and the coverings used in conjunction with DITRA-HEAT must be suitable for the respective application area and meet the corresponding requirements. Wait at least 7 days after completing the covering assembly to heat up the DITRA-HEAT-E system for the first time.

Installation on non-ceramic coverings:

Non-ceramic coverings such as wooden parquet, vinyl, PVC coverings etc. may be installed over DITRA-HEAT, both as floating coverings, including sound insulation, or as directly adhered coverings. The maximum thermal conductivity resistance of the upper floor covering, including a possible impact sound insulation, of Rlmax = 0.15 m² K/W should not be exceeded. The manufacturer instructions for the corresponding covering must be observed.

Please consult our Technical Department before using non-ceramic coverings in conjunction with DITRA-HEAT.

  • Install the DITRA-HEAT matting and the heating cable as described above.
  • Apply a low-stress levelling compound and filler that is suitable for an electrical floor heating system over the entire area in such a way that the gaps between the studs are completely filled and the heating cable and the pipe penetration sleeves are fully embedded.
  • It must be guaranteed that the heating cable and the studs are covered with at least 5 mm of the levelling compound. To ensure enhanced distribution and a more even surface, we recommend a coverage of at least 8-10 mm. A larger coverage also improves the load transfer in case of soft floor coverings (e.g. carpet) and results in more even heat distribution.
  • The upper floor coverings can be installed according to the manufacturer instructions once the levelling compound has sufficiently cured.

Set the digital thermostats Schlüter-DITRA-HEAT-E to "Soft floor" to limit the maximum floor sensor temperature to 28°C. If the manufacturer of the respective upper floor covering specifies different temperatures, these must be reflected in the settings.

Note for installing DITRA-HEAT in wall areas:

To mark the heated wall space (and avoid inadvertent drilling into a heating cable), we recommend using Schlüter profiles to visually outline the corresponding area (for more details, see data sheet 6.4 on page 4, see Downloads).

In the case of heated wall areas exceeding a length of 3 m, the wall and connection joints must have a permanently elastic design to accommodate thermal expansion.


Waterproofing with Schlüter-DITRA-HEAT

DITRA-HEAT can be used to create certified waterproofing assemblies with tile coverings, provided the abutting membrane joints and the connections to installed components and upright building structures are carefully sealed.

DITRA-HEAT also features the national technical approval (abP) required in Germany and has an Ü-mark quality seal for construction products.

Moisture load class according to abP: 0 - B0 and A.

DITRA-HEAT has a European Technical Assessment (ETA) in accordance with ETAG 022 (watertight covering kits) and bears a CE mark.

Moisture load class according to ETAG 022: A.

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 at the address listed in this data sheet for further information about such tile adhesive products and the corresponding certificates of technical approval.

DITRA-HEAT protects the substrate from damage caused by permeating moisture and aggressive substances. For joint sealing, trowel the sealing adhesive Schlüter-KERDI-COLL-L over the abutting joints and fully embed Schlüter-KERDI-KEBA in a minimum width of 12.5 cm over the join.

To waterproof floor-wall transitions, adhere KERDI-KEBA over DITRA-HEAT on the floor and directly on the substrate in wall areas in the corresponding width. The sealing band must have a coverage of at least 5 cm. KERDI-KEBA can also be used to create functional connections to fixed structural components such as door and window frames made of metal, wood or plastic.

The first step is to apply Schlüter-KERDI-FIX to the adhesive surfaces of the structural elements. The remaining width is then adhered to DITRA-HEAT with KERDI-COLL-L.

The suitability of KERDI-FIX for the respective materials of the structural elements must be verified in advance. Separate DITRA-HEAT at existing movement joints or expansion joints and seal the abutting joints with Schlüter-KERDI-FLEX. Never run heating cables over expansion joints or dummy joints.

KERDI-FLEX should also be used for flexible finishing edges. As an alternative, this can also be done with a sufficient loop of KERDI-KEBA.

Note regarding floor drains:
Schlüter-KERDI-DRAIN and Schlüter-KERDI-LINE are drainage systems specially designed for connection to bonded waterproofing assemblies. DITRA-HEAT can easily and quickly be combined with these components by using pre-fabricated KERDI collars.

The heating cables of the DITRA-HEAT system may only be operated with DITRA-HEAT-E thermostats.

What this product is made from

Schlüter-DITRA-HEAT 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. 5.5 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

DITRA-HEAT 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 below is intended as a general guideline.

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

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

How to look after this product

The thin-bed tile adhesive and the covering material used in conjunction with DITRA-HEAT must be suitable for the respective application area and meet the corresponding requirements.

If the covering materials to be installed are sensitive to moisture (e.g. natural stone or agglomerate stone pavers) or if moisture is present on the underside (e.g. from green screeds), the abutting joints of DITRA-HEAT mats should be fully covered with the sealing adhesive Schlüter-KERDI-COLL-L, and completely covered with the sealing tape Schlüter-KERDI-KEBA with a minimum width of 12.5 cm.

The use of quick-curing cementitious tile adhesives may be an advantage for certain projects. It is recommended to set out running boards to protect DITRA-HEAT from mechanical stresses caused by material transport.

Notes on movement joints:

Separate the DITRA-HEAT membrane over existing movement joints. Never run heating cables over movement joints. Continue the movement joints in the tile covering as specified by the applicable standards. Otherwise, divide large coverings installed over DITRA-HEAT into sections, using movement joints according to the applicable regulations.

We recommend using the profiles of the Schlüter-DILEX family. Arrange profiles such as Schlüter-DILEX-BT or Schlüter-DILEX-KSBT over existing expansion joints depending on the anticipated structural movements.

It is important to prevent stress build-up at the edges of the covering, for instance at upright structural components or at floor-wall transitions. Edge joints and connection joints must be constructed according to the applicable technical regulations and have sufficient dimensions to prevent stress build-up. We recommend using the various profile types of the DILEX family.