External tiling: solving the drainage problem

Did you know that it is estimated that more than 50% of coverings on balconies and terraces are damaged in Northern Europe due to poor installation systems?



A lack of suitable drainage beneath ceramic, pavers and natural stone tiles fixed externally can cause a number of issues including cracked tiles, efflorescence, and stained or patchy tiles – all of which are derived from water damage.

Problems arise when water sits on tiles/pavers and cannot drain off the surface or sufficiently through the tiles, joints or screed. When there is nowhere for the water to go, it is trapped in the screed and rises to the tiled surface (this is called capillary active).

The solution to this problem is a capillary passive drainage system -surface water that is absorbed into the tiled substrate is drained away from the screed and completely removed.

The solution is provided through the patented drainage mats from Gutjahr System Technology, now available from BAL.

There are two drainage mats within the range, both providing market-leading benefits.

AquaDrain EK (the blue mat) has a mesh and is designed for use with most tile types on drainage mortar or epoxy drainage mortar. While the drainage mortar and epoxy screed is capillary active, allowing faster movement of water from the surface through the screed to the base, is the water is not removed it can rise again. That is why the EK mat system is needed to completely remove the water from the system.


The green AquaDrain T+ has a specially designed fleece and is used with a direct point adhesion laying system for thin-layer, lightweight outdoor coverings.  With the AquaDrain T+, tiles are fixed at points on the surface drainage mat. There is no need for water-retaining mortar layers, and seepage water is rapidly shed through the mat’s drainage channels.

Both available in 8mm or 16mm depths for variable height build-ups and fast passive drainage, the innovative mats are designed with special meshes and fleeces, tailored to the specific requirements of the covering and laying method.  The patented “arch” shape guarantees the fleece/mesh does not sag and reduce drainage like some alternative mat systems.

Thanks to the unique arch system, and mesh/fleece which prevents the lime and mortar entering the cavities, the mats have more than 90% drainage volume – guaranteeing the fastest and best drainage volume in the market.

Alternative systems employ “dimples” where drainage capacity is much weaker, due to the sagging effective of the mesh into the drainage channels, blocking the flow of water. A 12mm alternate mat often performs lower than an 8mm AquaDrain mat!

Gutjahr drainage mats also have a 66% contact area on the channels, meaning an optimal load distribution, protecting the membrane from collapse.

Many specifications recommend uncoupling mats and not drainage mats for external tiling, but this causes problems of its own. Specifically that uncoupling mats only uncouple, and have no drainage capacity. Cavity mats are even more counter-productive as they retain water in their cavities and are capillary-active!

So it’s clear that simply fixing externally with just adhesive or drainage mortar/gravel will not prevent costly damage and the use of a drainage mat system is highly recommended.

At BAL we will be putting on specialist Gutjahr training sessions to show interested fixers and contractors the ropes. If you’re interested in signing up to a Gutjahr training session, please email training@bal-adhesives.com.

To find out more about Gutjahr System Technology, part of BAL External Tiling Solutions, please visit www.bal-adhesives.com/external-tiling/ and select your zone.