External tiling systems for balconies, roof terraces and ground floor terraces

By Stuart Ross, BAL Technical Advisory Service Supervisor

With space at home a premium these days, more and more people are expanding their living spaces outwards to create much needed, usable space.

In September 2011 a publication by the Royal Institute of British Architects entitled “The Case for Space” showed results from a survey that indicated 49% of people moving home wanted more outdoor space they could enjoy, this was more than those wanting larger internal rooms or the proximity of local services.

This trend for outdoor living has led to a growth in domestic markets for balconies, large roof/ground floor terraces and patios. There are variations in design and coverings, with larger installations no longer reserved just for commercial sector buildings such as hotels and sporting venues.

As well as adding monetary value to a property, tiled external areas can be aesthetically pleasing, offering a wide range of colours, textures and finishes. Inside/outside tiling is preferred over cheaper alternatives mainly due to its durability, longevity, life-cost (replacement of materials etc.), and for being low maintenance and subsequently easy to clean than other non-tile coverings and structures.


Outside living can also offer and promote health and well-being benefits as these extra useable areas for open air living, help to soften heavily urbanised locations and steadily increase the number of green and usable spaces.

Balconies, roof terraces and patios are part of a trend and are inspired by aspirational and luxury living in both suburban and rural areas.

When specified with the correct tiling systems, all types of tile installations are possible for outdoor use including ceramics, porcelain, some natural stone and pavers.

With the right products, these long-lasting balconies and terraces can be designed and installed for all year round enjoyment. These important extensions of our living areas should be well constructed, functional and remain as usable as the internal spaces that we occupy frequently. To ensure their availability the tile coverings used must be durable, hard-wearing and all-weather.

Recent estimates are that more than 50% of all coverings on balconies and terraces are damaged in Northern Europe due to poor installation and incorrect systems.

The challenge historically has been that poorly constructed tiled areas have resulted in visible damage including; cracked tiles, efflorescence, stained or patchy tiles – all derived from water. When water ingress and retention is combined with fluctuating temperatures, the outcome can prove destructive to both the covering and potentially the substrate.

What happens is that water penetrates to the lower levels of the assembly which can pose a serious risk to the covering but also the structural integrity of any installation. Over time the water permeation travels through the various layers via the tile joints eventually reaching the waterproofing where there is no escape. This puts more reliance on the waterproof membrane to be functional where should damage occur and because of no provision being made for water to drain away efficiently, the more chance it has to sit and find weak points in the primary layer.


Ensuring rapid-drainage of the tiled surface
The British Standards recognise the need for evacuating water quickly and efficiently. Taking the water out of the adhesive bed and assembly reduces the risk of most problems faced by modern external constructions.

BS 5385 Part 2 2014, Balconies and roof terraces states: “The formation of soluble salts can occur when water becomes trapped for prolonged periods of time within cement-based products.
“It is important that balconies and terraces should therefore be designed and constructed as to allow water to drain free and effectively.”

To ensure that moisture staining, frost damage and efflorescence do not become problems, it is crucial to specify the right products. It is vitally important to remember that water sensitive tiles and slabs should not be used externally.

The correct combination of products and materials make these issues highly preventable using:

  • Appropriate drainage assemblies – ones with effective falls, drainage and often with reduced thickness.
  • Suitable backgrounds – non-absorbent, solid, unaffected by temperature fluctuations and preferably cementitious
  • Correct selection of adhesive and grout – rapid setting/low water demand i.e. white for light natural stone such as BAL Rapidset Flexible Fibre or BAL Stone & Tile PTB.
  • Tile/slab selection – with low porosity, break-proof, suitable for external use.


Traditional assemblies and backgrounds
Over the years, a number of traditional methods have been used for external tiling including traditional cement:sand fixing directly onto screeds, fixing onto thick drainage screeds using a larger aggregate, loose laid slabs and stone onto gravel beds, and pedestal systems.

While each has their individual benefits, they also come with potential issues. Some of the traditional installation methods can have design limitations including excessive working depths, heavier loadings/weights, length of time to install and occasionally questions on stability.

For example, whilst traditional screeds may be easy to lay, they can absorb large volumes of water with little route of escape and nowhere to drain. Any water that is not removed from the assembly can sit at the waterproofing level at the lowest point and become trapped where the water can then expand during the freeze/thaw cycle affecting the screed integrity which in turn leads to void formation.

Loose-lay systems are again relatively expedient and easy to install, but without proper consideration to drainage below, water can rise back up through the gravel. This can cause water sensitive tiles and slabs to become stained. What’s more, joints which are left open can lead to weed growth, algae and moss build-up and other organic forms of contamination. Tiles of a suitable thickness for self-support should be selected.

Another popular system for installing external tiles is the use of plastic and mortar pedestal, either using dabs of mortar/adhesive or pre-fabricated adjustable versions. However staining can be a problem when the tiles or stone are moisture sensitive. In the past spots of staining can be found where the support is concentrated.

The use of a drainage screed has many benefits over traditional sand:cement screeds. Cavity rich, with lots of capillaries, the water drains through quickly and efficiently. With reduced shrinkage and deformation and combined with a quick-setting cement for fast-track installation, drainage mortar seems the ideal solution. However drainage screeds alone will not cure the drainage problem. This is because drainage screeds do not accommodate drainage on the horizontal plane, meaning water will drain effectively through the screed but not out to the perimeter. This can cause the build-up of soluble salts and lime, which can be destructive to cement-based products and can often result in unsightly residues or visible salt deposits.

BAL External Tiling Systems – the drainage solution
There are solutions surrounding fixing tiles externally. BAL have launched a new external tiling system including exclusive technology from its sister company Gutjahr. The BAL system works to protect outdoor coverings from the unpredictable British weather and some of the issues highlighted previously.

Gutjahr System Technology from BAL offers architects, designers and contractors innovative drainage solutions for all types of assemblies, especially useful for helping to create seamless transitions from internal to external living spaces.

The new products represent a complete range of solutions for the BAL portfolio and work as a system with current BAL preparation, adhesives, grouts and sealant products.
This means for the first time architects, designers and contractors are provided with a true ‘one-stop-shop’ for balcony, terrace and patio systems for a range of different coverings
Gutjahr are the inventors of the passive capillary drainage system, combining the use of AquaDrain® drainage mats, a drainage screed, ProFin® drip edge profiles, ProRin® guttering and AquaDrain® drain grates.

These patented systems are simple to install and provide rapid, immediate and high volume drainage of water. Water is drained down through the screed and transported from the assembly by the use of a drainage mat, meaning no water staining, no freeze/thaw threat or efflorescence.

Meeting height and weight requirements
BAL offers three systems for architects and specifiers, each designed to meet height and weight requirements of varying constructions.

Among the systems on offer from BAL include Thin Drainage Assembly with direct point adhesion for break-proof tile and stone coverings, Standard Drainage Screed Assembly for the solid bed fixing of ceramic, porcelain and natural stone and concrete paving, and a Thin, Lighter Weight Drainage Screed Assembly with an epoxy screed for a strong but comparatively lightweight build-up compared to conventional systems.

The Thin Drainage Assembly allows a minimum build-up from only 29mm when using a 20mm slab and 8mm mat. Suitable for 20mm porcelain and 30mm natural stone (minimum), the system combines the use of the AquaDrain® T+ drainage mat,  BAL Rapidset Flexible Fibre tile adhesive, ProFin® V profiles, the shallow AquaDrain® TM drain grate and a special cement-like neutral-curing sealant – MorTec® SOFT – for external use.

With this system tiles are fixed onto the drainage mat using special pads of adhesive. This reduces height build-up and the need for the design of movement joints, as each tile joint effectively allows movement.

The Standard Drainage Screed includes the use of AquaDrain® EK drainage mat, a drainage screed, selected ProFin® drip drain edge profiles, BAL Stone and Tile PTB tile adhesive, AquaDrain® FLEX drain grates, and ProRin® guttering if required. The system can be grouted with BAL Micromax2 grout.

With a height build-up of 58mm, the standard drainage screed also allows for the solid bed fixing of ceramic, porcelain, natural stone and concrete paving. Minimum tile thickness for this assembly is 10mm porcelain/ceramic and 20mm natural stone/pavers.

BAL is also offering a Thin, Lighter Weight Drainage Screed assembly which utilises MorTec® DRAIN – an epoxy-based drainage screed – for a strong but comparably lighter weight compared to conventional screeds, with build up from only 43mm (excluding the tile) for low height constructions.

Rainproof after only three hours (approximately), the MorTec® DRAIN epoxy screed saves time and prevents mixing errors – with no weighing of individual screed components required.
This system is suitable for minimum 10mm thick porcelain tiles and 20mm natural stone tiles/pavers.

Tiles should be fixed with a flexible and rapid-setting adhesive such as BAL Rapidset Flexible Fibre, and the system grouted with the flexible and anti-microbial BAL Micromax2 grout which is available in a number of different colours.

BAL’s external tiling solutions provides for a number of different edge finishes, depending on screed thickness, tile size and thickness and the desired look. Edge profiles are available in a number of heights thanks to the modular system, meaning that tiles can sit flush, overhang the profile or even protrude.


Proven across Europe
For more than 25 years, BAL’s sister company Gutjahr have developed long-lasting trouble-free coverings even on problem substrates throughout Europe for prestigious projects including Amsterdam Library, Schloss Elamau – site of the G7 summit in 2014, The Palace of Hambach, the Frankfurt Airrail Centre and the Weimar National Theatre.

Gutjahr has also been used on the Baden Hut at 2,608m above sea level in the Austrian Alps, to protect a sun terrace against extreme frost, snow, rain and heat in the summer months. So remote was the project, materials were transported to their destination via helicopter.

Gutjahr’s technology is so proven and reliable that it has even become a standard in Germany since 2002 being incorporated into the standards for external floor coverings of the German Construction Industry Association (ZDB).

Now part of the BAL range, Gutjahr system technology represents a breakthrough in the UK market for simple, safe and trusted solutions for outdoor tile installations.

Free specification and project support
As well as innovative products to meet the growing need for external living spaces and ensure that outdoor surfaces look great and remain usable all year round, BAL provides a whole host of support services for architects, designers and contractors from design to build including:

  • Free M40/M20/M10 specification writing service
  • RIBA-accredited CPDs
  • Bespoke system training and masterclasses
  • BIM objects in NBS National BIM Library
  • Fast-Track Project Enquiry and market-leading Technical Advisory Service
  • Sample testing service
  • National Specification Support Team for advice or on-site consultancy
  • Innovative range of products for full tiling systems
  • Leading product guarantee
  • Nationwide Product Support Technicians for on-site consultancy
  • BAL also has comprehensive online tools and web features including:
  • Product information including downloadable Technical Data Sheets and Material Safety Data Sheets
  • Free project specification
  • Technical Design Guide and Installation Guides available to download.
  • Case studies and gallery of images
  • Technology demonstration requests
  • FAQs and technical advice

To find out more about BAL’s new external tiling system visit www.bal-adhesives.com call our Specification Team on 01782 591120 or email info@building-adhesives.com.