Raimondi RAI-FIX Mechanical System
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for fixing Large Format Tiles to the Wall
before quickly cutting and fixing the lower course(s). This saves time, and remarkably it can often be achieved without the use of spacer pegs. In spite of this there are other factors which have to be considered before tiling commences, in particular the background surface preparation, the physical properties of the tile, and the finished height of the tiling.
Background preparation and tile characteristics Fixing 300 x 600mm and larger sizes is fine if the existing walls can withstand the weight of the tile. Although no published standards cover the maximum weight, 32 kilograms per square metre is frequently quoted as the maximum load bearing capacity of the most common backgrounds that are tiled in Australia and elsewhere. Given that a square metre of 300 x 600 x 10mm tiles weighs approximately 21.66 kilograms – and a square metre of 600 x 600 x 10mm weighs roughly 24 kilograms – we can see that these sizes are manageable providing the shear strength of the chosen adhesive is greater than the quoted figure of 32 kilograms. Critically the background needs to be flat, smooth, plumb and free of any contaminants that might retard adhesion. Weight considerations should recognise the fact that certain materials can increase in weight when they become wet. This is particularly true of absorbent stone materials like sandstone. When products like sandstone become saturated the composition of the stone can actually weaken and delaminate. Furthermore, certain backgrounds lose strength when wet, which can reduce the capacity of the background to bear the weight of the tiles. The installed materials can be affected by radical changes in temperature.
Fixing methods In previous editions we have illustrated a wide variety of projects which feature ceramic tiles fixed with adhesive to heights exceeding 3 metres – the highest applications deemed to be safe when fixing tiles with conventional adhesives. Adhering 152 x 152mm tiles or mosaic to a building façade at heights greater than 3 metres poses less of a risk to the general public than adhering heavy porcelain or natural stone tiles. Each case has to be considered on its merits. The 3 metre height should also be generally adopted for internal tiling projects. Adhesive fixing can be successfully combined with some mechanical systems to allow tiling to extend beyond 3 metres. Mechanical fixing systems provide an opportunity to fix the heaviest modules of tile and stone at virtually
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3 – The Raimondi Rai-Fix system effectively combines mechanical support and use of an appropriate adhesive to fix ceramic tiles. (Image courtesy of B.A.T. Trims Australia)
any height, providing the building can bear the load.
Adhesive Fixing According to AS 3958.1 – 2007 large format products like 300 x 300mm should be adhered using a 12mm notched trowel. Larger formats (e.g. 400 x 400 and 300 x 600mm) must be fixed by first applying adhesive to the background and then adding a thin skim of adhesive, using the flat side of the trowel, to the back of the tile. When the two surfaces are pressed together and the tile is moved at least the width of one of the parallel ribs of adhesive, created by spreading adhesive with the notched trowel , the minimum required adhesive coverage should be achieved. The appropriate contact coverage figures quoted in the Standard are:
• Internal
residential walls: 65 per
cent
• Commercial and industrial walls: 80 per cent
• Wet areas: 90 per cent • External 1. Batwalls: trims90 per cent • Swimming pools: 90 per cent
Our major adhesive manufacturers all provide guidance in relation to use of their products. Architectural engineers should consult with the adhesive supplier before conclusively deciding on a fixing system. Whichever fixing method is employed the substrate should be allowed to cure fully, and the possibility of shrinkage should be carefully evaluated before tiling commences. At all times the potential risk to the public should be evaluated. Ardex Technical Bulletin TB001.008 makes the point that when selecting the weight limit (kg/m2) for the nominated background, in comparison to the maximum tile weight, the lowest value must be selected. For example a 12.5 kg/m2 rated background would not be suitable for to support a 400 x 400mm tile of 26 kg/ m2, but would be suited to a larger, but lighter product which only weighed 11.1 kg/m2. In those circumstances the 400 x 400mm tile would require a combination of mechanical and adhesive fixing. 2. Novatex Products
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B.A.T Trims is proud to introduce the raimondi Optimus Non-Porous Primer is a specially Mechanical Fixing system be for spread the wall application formulated primer designed Large ashlar units of natural stone for enhancin Onrai-Fix walls mechanical adhesive should of ceramic and marble slabs. It is a precise fixing adhesion to non-porous have been successfully fixed over aand smooth surf horizontally to prevent water travelling device for large format products (exceedinggreat 40 x many years Optimus Non-Porous Primer provides sup in Australia. David downwards along the serrations created 40cm) that are at least 8mm thick. This mechanical bonding properties to metals, plastics an West, a former structural engineer by thesystem trowelled is notadhesive. a replacement for adhesive but an surfaces. Optimus Non-Porous Primer is s with Ove Arup, advises that hundreds additional aid. Grind a slot into the tile and fit a free and non-hazardous, it eliminates the of façade projects been installed Combining Adhesive and stainless steel Rai-Fix hook before mounting both for have solvent etching or mechanical grindin in the Sydney CBD alone. In recent to be compa Mechanical Fixing to the wall. primer is specially designed times a numberallofNovatex projects have fea- membranes, a In situations where the completed waterproofing B.A.Tis Trims tured Buchtal ceramic tilestowhich heightcontact: of the tiling scheduled to finish and renders enableposreliable adhesion t 9797 7900 sess proven hydrophilic above03 a height of 3 www.battrims.com metres, adhesive can surfaces. air cleaning capabilities. Many mechanical systems be used in conjunction with a variety Products have been tried. contact: Buchtal Novatex manufactures of mechanical supports. This provides (02) 9757 3525 www.novatexproducts.co a state-of-the-art system which comadded assurance and allows specifiers bines horizontal support rails fixed to to use heavy units of tile or stone withperpendicular posts. The tiles are swiftout adopting full scale mechanical fixly slid into position and secured at an ing procedures (Photo 3).
94 tile+ stone showcase
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