Compact Knowledge – Waterproofing standard DIN 18534

DIN 18534

The standard DIN 18534 is based on DIN 18195, which regulates the planning and execution of all types of building waterproofing. However, DIN 18195 now only provides the framework for the various building waterproofing sectors, since it was broken down into the standard series 18531 to 18535. These include: 

• DIN 18531 Waterproofing of non-utilised and utilised roofs
• DIN 18532 Waterproofing of concrete areas trafficable by vehicles
• DIN 18533 Waterproofing of elements in contact with soil, waterproofing in and under walls
• DIN 18534 Waterproofing for indoor applications
• DIN 18535 Waterproofing of tanks and pools

The standard DIN 18534 is therefore decisive when it comes to waterproofing in bathrooms and the waterproofing of level-access showers. It has been effective since 2017. Planners and tradespeople benefit from the new standard in two ways: firstly, this standard covers state-of-the-art technology, which means bonded waterproofing is now also finally covered - and while this has proven to be a reliable solution for the waterproofing of wet areas, until now it needed to be contractually regulated as a special structure in each individual case. And secondly, it now provides a binding code of practice. Until now, the waterproofing of interior spaces was regulated by a range of data sheets and guidelines published by the Central Federation for the German Building Industry (ZDB) and by the standard DIN 18195.

Correctly waterproofing level-access showers

The new standard offers uniform, current rules for the waterproofing of buildings that are clear and concise. This provides much greater on-site clarity and safety in the execution of waterproofing and a clear-cut allocation of tradespeople to specific tasks. However, DIN 18534 also takes into account the special challenges faced when waterproofing level-access showers, such as the fact that during installation and waterproofing, the seal beneath the floor covering and adhesive needs to be established during installation. Bonded waterproofing is now recognised as state of the art. When waterproofing installations according to DIN 18534, a range of different factors needs to be taken into account – primarily the type of connection, flange width and so-called water exposure classes.

Types of connection

In order to ensure that the drainage solution is permanently waterproof, it needs to be correctly installed in the substrate. DIN 18534-3 regulates the structural connection of the flange (on the drain body) to the sealing sleeve, which is incorporated in the bonded waterproofing.
There are three reliable types of connection: 

• Client-supplied adhesive bond of a sealing sleeve
  The difficulty with this sort of connection is that – when the flange width is between 30 and 50 mm – it must be verified that the connection of the bonding flange to the sealing tape or sealing sleeve using system-compliant sealant adhesive has been executed in accordance with the manufacturer specifications. 
• Factory connection of a sealing sleeve
  While the factory connection of the flange with the sealing sleeve avoids the previous problem, it has proven not such a convenient solution on-site as a sealing sleeve first has to be pressed between the loose and the fixed flange. 
• Client-supplied adhesive bonding of a sealing sleeve
  Sealing sleeves that are simply clicked onto the drain body have proven particularly practical, as it is not clicked on until the bonded waterproofing is successfully completed.
  

Flange widths

In the section "Detail formation" (Section 7.6) of DIN 18534-3, it also states that the "flange width on drainage channels, floor drains and installed parts (…) must be at least 50 mm." However, this does not apply to factory-fitted sealing sleeves. If floor drains are installed in heavy-duty areas, such as in public in-line showers, the flange width must also be a minimum of 50 mm, and the sealing sleeve on the adjoining area must also overlap by > 50 mm.

Requirements on the flange width, depending on water exposure class
*Manufacturer certificate for drain and sealing sleeve when using system-compliant sealant adhesive.

Water exposure classes

The various demands made on waterproofing due to the effects of moisture on walls and floors are defined in DIN 18534-1 using four water exposure classes, W0-I to W3-I. The longer an area is exposed to water, and the greater the volume of water, the greater the level of waterproofing required in order to prevent moisture damage.

Water exposure classes acc. to DIN 18534

Water exposure classes in private bathrooms: the floor areas of level-access showers are subject to heavy-duty exposure.

A level-access, tiled shower in the private sector, for example, corresponds to water exposure class W2-I. In this case, the waterproofing must be installed with crack-bridging, mineral sealing slurries or reaction resin. Alternatively, sheet waterproofing is also suitable. Waterproofing with polymer dispersion coatings is only suitable for areas that are merely exposed to splash water (wall area). However, in the case of in-line showers installed in sports clubs or businesses, both floors and wet walls fall under water exposure class W3-I, whereas the "splash area" in front of the installation is water exposure class W2-I.

Standard-compliant solutions

Dallmer has been a key driver of the technical development that is now reflected in the new standard. All Dallmer drainage systems that accommodate bonded waterproofing meet the requirements of DIN 18534. For example, the newly required flange width of 50 mm for shower channels and floor drains has been standard at Dallmer for years. This is just one of the reasons why the installation and waterproofing of Dallmer products is so straightforward. The following examples show how:

DallFlex drain body

Assembly of the DallFlex drain body retains the clear separation of tasks so valued by practitioners: the plumber installs the drain on the unfinished floor and connects it directly to the drainpipe. The drain body is then precision-fitted flush in the screed. The sealing sleeve with the required width is then just clipped into the housing prior to application of the bonded waterproofing. If the drain is being fitted in an area with water exposure class W3-I – such as public in-line showers – the flange width and overlapping must meet more stringent requirements. But even in such cases, the on-site installation process for DallFlex drains remains the same, as the width of the sealing sleeve surrounding the drain is generally 100 mm and, just as is the case with house installations, it is simply clipped into the drain body.

DallFlex shower underlay

A so-called shower underlay makes it particularly easy to meet the waterproofing requirements for shower areas. The DallFlex shower underlay from Dallmer comprises a continuous waterproof area so that it meets the requirements of water exposure class W2-I. The required 2% slope in the shower area, or approx. 2 cm (in the case of front-of-wall drainage solutions), is already integrated in these shower underlays. This factory-fitted feature is now even more important as even the new DIN 18534 does not stipulate a specific slope. As with flush-in-floor drains embedded in the screed and bonded waterproofing, the waterproofing of the shower board must also be installed using crack-bridging, flexible sealing sleeves as per the respective water exposure class.