Schluter Waterproofing and Uncoupling Mats - Ditra

APPLICATION AND FUNCTION

Schluter-DITRA is a polyethylene membrane with a grid structure of square cavities, each cut back in a dovetail configuration, with an anchoring fleece laminated to its underside. Designed for ceramic tile and natural stone installation, Schluter-DITRA serves as a water­proofing membrane and as a vapour pressure equalisation layer to accommodate moisture occurring at the underside. It also acts as an uncoupling layer for problematic sub­strates.
To bond Schluter-DITRA, use a bonding adhesive that is appropriate for the substrate. Apply using a 3 mm x 3 mm notched trowel. The anchoring fleece on the underside of Schluter-DITRA must be fully engaged in the adhesive to provide a mechanical bond to the substrate. Using the thin-bed method, set the tile covering directly onto Schluter-DITRA in such a way that the tile adhesive becomes mechanically anchored in the cut-back cavities of the Schluter-DITRA matting.
Schluter-DITRA is also suited as a support matting for covering materials such as, e.g. plaster or screed.

Summary of Functions

a)  Waterproofing
Schluter-DITRA is a polyethylene waterproofing membrane with a very high vapour diffusion density. Provided the joints, wall/floor connections, and connections to building fixtures are properly installed, Schluter-DITRA creates a waterproofing layer for installations not exposed to con­stant water pressure. Thus, Schluter-DITRA protects the substrate against damage due to moisture penetration and aggressive or harmful substances.

b) Equalisation of vapour pressure
The interconnected air channels between the cavities on the underside of the Schluter-DITRA matting remain open, allowing moisture in the substrate to evaporate, thus neutralising vapour pressure.

c) Uncoupling (separation)
Schluter-DITRA uncouples the floor covering from the substrate and prevents the transfer of stresses to the tiled surface. Thus, stresses caused by deformation of the substrate are neutralised. Likewise, stress cracks in the substrate are bridged and are, therefore, not transferred to the surface covering.

INSTALLATION

1. The substrate must be even, load bearing, and free of contact-inhibiting material.
2. The type of bonding adhesive used to apply Schluter-DITRA depends on the type of substrate. The adhesive must bond to the substrate and mechanically anchor the fleece on the underside of the Schluter-DITRA. For most substrates, a dry-set tile adhesive is suitable.
3. Apply the bonding adhesive to the substrate using a 3 mm x 3 mm notched trowel.
4. Individual courses of Schluter-DITRA are cut to size. Solidly embed the anchoring fleece on the underside of Schluter-DITRA into the adhesive so that its entire surface is bonded. Work Schluter-DITRA into the adhesive, in one direction, using a float or screed trowel. When initially positioning Schluter-DITRA, it is advisable to align it precisely (lift one end, pull lightly, and place the stretched membrane). Application is made easier with a second person. The side edges and ends of individual strips are cut straight and butted together.
5. Once installed, the matting must be pro­tected against heavy mechanical loads to avoid loosening it from the substrate or other damage. It is advisable to place running boards to protect the Schluter-DITRA.
6. Immediately after the DITRA matting is installed, the tiles can be laid on top using the thin-bed method. It is advisable to apply the tile adhesive in a single process using a notched trowel. Install the tiles, ensuring full coverage. Match the notch size of the trowel to the type and format of the tile. Please observe the open time of the adhesive.
7. Schluter-DITRA is cut above existing expansion joints. If Schluter-DITRA is used as a waterproof membrane, Schluter-KERDI-FLEX is adhered over the joints. According to the applicable standards, movement joints are to be carried over to the tile coverings. Large surfaces are to be divided into smaller fields in accordance with applicable standards. We recommend the Schluter-DILEX profile series. Depending on the expected movement, appropriate movement profiles such as Schluter-DILEX-BT or Schluter-DILEX-KSBT are to be incorporated above structural joints.
   

MATERIAL

Schluter-DITRA is a polyethylene sheet with a grid structure of square cavities, each cut back in a dovetail configuration. An anchoring fleece is laminated to the under-side. The rib height is approximately 3 mm.

Material-Properties and Areas of Application:
Schluter-DITRA is flexible and bridges cracks. In addition, it does not rot. It is highly resistant to solutions containing salts, acids, and alkalis, as well as many organic solvents, alcohol and oils. Its resistance to specific stresses can be provided if con­centration, temperature, and exposure time are known. Its imperviousness to steam is very high. The material is physiologically safe. It must be verified that substrates, which are to receive the Schluter-DITRA, are clean, even, and load bearing. Contact-inhibiting surfaces must be removed prior to the application of Schluter-DITRA.

Notation
The contact surface of Schluter-DITRA amounts to approximately 50% of the total surface. This can reduce the load-bearing capacity in case of point loads. For high point loads, select a tile thickness that can distribute the loads. The tile dimensions should be at least 5 cm x 5 cm.
For the installation of moisture-sensitive covering materials (natural stone, epoxy agglo-merates) over substrates where moisture is to be expected, e.g., green concrete, DITRA is to be installed as a waterproof membrane. For exterior applications of Schluter-DITRA, special protective measures may be required, e.g., shade cover. The use of rapid-set adhesives may be advantageous for certain applications. Generally, only water, weather and frost-resistant dry-set tile adhesives are to be used on exterior applications.

SUITABLE SUBSTRATES FOR SCHLUTER-DITRA:

Concrete
Concrete is subject to deformation due to shrinkage. The time period over which this occurs is 6 to 12 months. Schluter-DITRA absorbs inherent stresses between the concrete and tile covering so that the tile can be installed as soon as the concrete is hard enough to walk upon. For wall ap­pli­cations, Schluter-DITRA can also be used as a support matting for plaster or similar.

Mortar screeds / Radiant heated screeds
As a rule, mortar screeds must cure a minimum of 28 days prior to the installation of tile so that deformation due to shrinkage subsides. Floating screeds and, in particular, heated screeds tend to change shape or develop cracks even later, e.g. due to load stresses or temperature changes.
Tile can be installed using Schluter-DITRA immediately after the screed can be walked upon. Seven days subsequent to installation, the radiant heated floor can be raised gradually by + 5° C per day.

Gypsum-based screeds
As a general rule, when installing tile over gypsum screeds, the residual moisture should not exceed 0.5% (percentage by volume). In addition, this substrate generally requires specific pre-treatment, as well as a special tile adhesive.
Using Schluter-DITRA and provided the substrate is sufficiently load bearing, the tile covering can be installed once the residual moisture does not exceed 2%.
Schluter-DITRA can be applied using dry-set adhesive or other tile adhesive suitable for the substrate.

Masonry
Masonry consisting of brick, stone, limestone, cement block, lightweight concrete, or similar is generally a suitable substrate for Schluter-DITRA. Uneven areas must be levelled in advance. Particularly in renova­tions or additions, different materials (mixed masonry) may be encountered. At the transitions, differential movement can cause cracks. With Schluter-DITRA, stresses and cracks do not transfer to the tile covering.

Gypsum plaster / Plaster block
When tested, the gypsum substrate should be considered dry according to accepted guidelines. It may be required that the surface be pretreated with a primer.
Schluter-DITRA is applied with dry-set mortar or other tile adhesive suitable for the substrate.

Balconies / Balcony renovations
Schluter-DITRA, in conjunction with the tile covering, can be used to waterproof balconies. Stresses, which frequently occur on balconies between the substrate and the tile covering (due primarily to temperature changes), are neutralised by Schluter-DITRA. For renovations, the existing surface assembly can generally remain, provided it is sufficiently sloped and load bearing. Prior to the application of Schluter-DITRA over existing and cracked tile floors, the loose tiles must be removed and the remaining cavities filled using an appropriate ad­he­sive.

Synthetic flooring and surface coatings
Fundamentally, the surface must be load bearing and prepared in such a way that a suitable tile adhesive will adhere to it and anchor the fleece on the underside of the Schluter-DITRA matting.

Plywood and particle board
These materials are particularly affected by moisture. Even strong fluctuations in humidity can cause deformation. Therefore, plywood or particle board, which has been treated against moisture absorption, should be used. In principle, plywood or particle board can be used as a substrate on both walls and floors. Choose a board thickness that, in combination with the existing substructure, will produce a stable substrate. Anchor the substrate by placing screws at appropriate intervals. Butt joints must be tongue and groove and they must be glued.
A distance of approximately 10 mm to ad­jacent structures must be kept. Schluter-DITRA neutralises stresses that occur between the substrate and the tile covering and prevents moisture penetration.

Structural plank flooring
A proven method is the addition of a ply­wood or particle board layer. Uneven floors must be levelled using an appropriate compound.

Bituminous screed
Schluter-DITRA allows ceramic floor coverings to be laid on load bearing bituminous substrates e.g. bituminous screeds in interior and exterior applications (flooring grade asphalt). Contact-inhibiting surfaces must be removed using appropriate blasting techniques. Generally, dry-set mortars with appropriate additives are suitable for adhering Schluter-DITRA.

Waterproofing with Schluter-DITRA
By carefully sealing the mat joints and connections, Schluter-DITRA can be used for waterproofing in applications not exposed to constant water pressure.
Therefore, wet areas classified as Exposure Group I to IV in the German Building Code (ZDB data sheet) can be waterproofed.

For sealing Schluter-DITRA, apply a dry-set tile adhesive and solidly adhere the 12.5 cm wide Schluter-KERDI Band. For floor/wall connections, adhere the Schluter-KERDI Band in the appropriate width (18.5 cm or 25 cm) using a dry-set tile adhesive. Firmly embed the Schluter-KERDI Band in the adhesive in such a way that it adheres to the DITRA on the floor and directly to the wall substrate. Overlap the sealing tapes at least 5 cm. If large amounts of water are anticipated, a suitable waterproof adhesive can be used to adhere the Schluter-KERDI Band.

Connections to fixed building elements can be made using the Schluter-KERDI Band. A suitable adhesive or an epoxy adhesive that will adhere to the fixed building element shall be applied to the adhesion surface area. Embed the Schluter-KERDI Band in the fresh adhesive, ensuring full coverage.

The residual width shall be bonded completely to Schluter-DITRA using dry-set mortar. When anticipating large amounts of water, an impervious adhesive (e.g. epoxy mortar) can be used to adhere the Schluter-KERDI Band.
Schluter-DITRA must be cut over existing expansion or structural joints and the joints covered with Schluter-KERDI-FLEX. Schluter-KERDI-FLEX is also used at flexible edge or corner transitions.

Floor drains:
Schluter-KERDI-DRAIN is a special floor drain, specifically developed to allow connections to a bonded waterproofing layer. This allows Schluter-DITRA to be applied easily and quickly.

Product Overview