Schlüter-TROBA-PLUS  Drainage mat for use over sloped waterproofing layers

Balconies and terraces must withstand all weather conditions with almost no protection. Such structures must be able to absorb and effectively drain away moisture to be durable and stand the test of time.

Installed between the waterproofing layer and the covering assembly above, the cone-shaped studs of Schlüter-TROBA-PLUS create a drainage space which means water can be channelled in the direction of the slope towards the drainage exit e.g. guttering, thanks to gravity. TROBA-PLUS also protects the waterproofing layer from damage caused by extreme temperature changes.


Product image TROBA-PLUS 1©Schlüter-Systems KG
Cross-section drawing TROBA-PLUS 1©Schlüter-Systems KG
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Product image TROBA-PLUS 1
Cross-section drawing TROBA-PLUS 1

General product information

What this product does

Schlüter-TROBA-PLUS is a reliable and permanently effective drainage layer for use in horizontal applications over sloped waterproofing layers. It consists of a high impact, studded polyethylene sheet that is covered on one side with a water permeable filter fabric.

As a closed polyethylene mat, TROBA-PLUS also protects the waterproofing layer. The closely spaced, truncated, conical studs have an extremely high load bearing capacity. The cavities between the studs and the filter fabric create a heat and sound insulating air space and protect the waterproofing membrane against harmful thermal stress.

Schlüter-TROBA-PLUS 8 raises the screed bed by 8 mm over the entire waterproofing surface. Schlüter-TROBA-PLUS 12 raises it by 12 mm. This results in an even load distribution over the waterproofing assembly and effectively bridges minor defects in the sloped waterproofing assembly, such as uneven or elevated spots in the overlap area, where water may back up. Larger uneven areas can be levelled with mortar before installing TROBA-PLUS.

How to install this product

  1. The load bearing substrate and the waterproofing layer placed on it must be adequately sloped toward and connected to the designated drainage exit. Prior to installing TROBA-PLUS, larger uneven areas in the sloped waterproofing assembly should be levelled with an appropriate mortar.
  2. Independent of the slope, TROBA-PLUS is placed loosely over the waterproofing membrane with the filter fabric side facing up. Adjoin sections by abutting the edges and overlapping the filter fabric.
  3. The surface assembly is installed directly over the placed TROBA-PLUS according to current industry standards.
  4. Note: We recommend our profile types Schlüter-BARA and Schlüter-DILEX for edging profiles, movement joints and floor-wall transitions.

Note: Natural shifts may occur in paver coverings over loosely installed crushed stone/gravel due to one-sided or corner loads.

Assemblies with a gravel or crushed stone bed exceeding a depth of 5 cm may have a minor bounce. We recommend the use of Schlüter-TROBA to avoid this effect; see product data sheet 7.1.

What this product is made from

Schlüter-TROBA-PLUS consists of a pressure stable, studded polyethylene sheet that is covered on one side with a polypropylene filter fabric. The material is dimensionally stable up to a temperature range of + 80°C.

TROBA-­PLUS 8 has a compressive strength up to 39 t/m², and TROBA-PLUS 12 up to 30 t/m². The functional and material characteristics are permanently guaranteed. The material is resistant to ageing and non-rotting. Cutting waste is non-hazardous. Polyethylene 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-TROBA-PLUS is used primarily in horizontal applications over sloped waterproofing layers. It forms an effective drainage layer between the waterproofing and the screed bed placed above it. Its main areas of application are terraces and balconies, but also include industrial structures, swimming pool decks, washrooms, showers, etc, which have been waterproofed.

The loosely placed TROBA-PLUS is adequately resistant to mechanical stresses incurred during the installation process, e.g. due to foot traffic and wheelbarrows. The covering assembly may consist of screed with or without tiles or can be a structure of pavers or stones installed over gravel or crushed stone beds (minimum height 5 cm).

Layers of soil or gravel are equally suitable.

Any water that penetrates the covering is collected in the stilted drainage area of TROBA-PLUS where it runs off, under normal gravitational force, toward the designated drainage exit. This prevents the permanent saturation of the load distribution layer with seepage water.

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