OUTDOORS ect external tiles and natural stone from water damage
prevention of void formation, efflorescence and lime bloom. This can also materialise through grout joints and at main water exit points as described below:
BS 5385 Part 2 2014, 6.8.1.4 Balconies and roof terraces states: “The formation of soluble salts can occur when water becomes trapped for prolonged periods of time within cement-based systems.
“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 in the future, 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 include:
• Appropriate drainage assemblies – structures with effective falls, drainage and often with reduced thickness.
• Suitable backgrounds - non-absorbent, rigid, fully cured and dry, unaffected by temperature fluctuations and preferably cementitious
• Correct selection of adhesive and grout – rapid setting/ low water demand
• Tile/slab selection – with low porosity, break-proof, suitable for external use i.e. frost resistant.
Traditionally, external tiles have been fixed directly onto sand:cement screeds, into cement:sand mortar beds, thick drainage screeds, loosely laid gravel bed or by using cement- based pedestal systems.
While each has their own benefits, such as ease of use and lower cost, they all fail to adequately deal with water effectively. For example, while traditional sand:cement
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screeds, thick drainage screeds and gravel all absorb large volumes of water, and are prone to the problems highlighted above, water can also travel back up through the screed, gravel bed or adhesive pedestal causing water sensitive tiles and slabs to become stained.
The use of a ‘passive capillary’ drainage screed is the answer – for example BAL External Tiling Solutions from Guthjahr. Cavity rich, with lots of capillaries, the water drains through quickly and efficiently and also offers reduced shrinkage and deformation. When combined with a quick-setting cement for fast-track installation, drainage mortar seems to be the ideal solution, however drainage screeds alone will not solve the problems with drainage alone.
The use of a complete drainage system, including drainage matting, drip/drain edge profiles, drain grates and guttering provide rapid and immediate drainage of water.
Water is drained down through the screed and transported from the assembly by means of a drainage mat – such as BAL Aquadrain EK or Aquadrain T+ - which is situated below the drainage screed and above the primary waterproofing system.
New to the UK market, the passive capillary drainage screed represents a completely new system for tiling externally – but is the only one that provides complete protection against the elements.
BAL can also now offer a pedestal system from Gutjahr – TerraMaxx TSL. The completely pre-assembled raised floor supports enable quick and simple laying of tiles/slabs on balconies, (roof) terraces and other walk-on surfaces. Rain- water runs off through the open joints. Pipe and power lines as well as floor gullies can be hidden in the cavity between the covering and the substrate and remain accessible. If required, individual tiles can be lifted and exchanged.
www.bal-adhesives.com/external-tiling/ OUTDOOR INSTALLATIONS | 33
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