Description #
Join us in this video to learn about the considerations you need to factor in when tiling over timber flooring. Including the risks you may face when tiling over timber, dealing with timber floors and surface deflection, and how to choose the right adhesives for the job.
Transcript #
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Hi everyone and welcome back to Prep, Set, Go. Today we'll be kicking off the
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first of a three-part video series on tiling applications, and specifically tiling over
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different types of surfaces - and not just your typical or conventional surfaces like concrete,
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plasterboard, or fibre cement sheeting, we'll be exploring the scenarios when you might come across
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these different surface types, the risks and associated challenges, as well as simple tips and
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recommendations on how to tackle it. So sit back, get comfortable, make yourself a nice cup of tea,
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or perhaps something stronger as we dive right in. In this video we'll be exploring the ins and outs
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of tiling over timber floors. So when might you come across timber flooring? Well it's actually
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quite common, particularly in new construction, in double story dwellings. Particle board - often
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referred to as yellow tongue, is often used as the upper story flooring. It comprises wood chips of
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various sizes, combined with synthetic resins, and compressed into boards. Protective wax coatings
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are often applied over for extra durability and weather resistance during the construction phase.
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Now renovations is an obvious example when you may encounter timber surfaces, often in
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the form of old strip timber or floorboards. So what are the risks of tiling over timber
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surfaces? The challenges with tiling over timber are not necessarily to do with the adhesion to
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the surface, but more to do with the contrasting properties of the two materials, timber versus
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ceramic. Now timber is a natural product - it's soft, pliant, and prone to movement,
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expansion and flexing, under load and exposure to moisture and humidity. While tiles on the other
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hand are typically hard, rigid, and unyielding, so this may give you some idea where the potential
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issues may lie. The biggest risk involved with tiling directly over timber surfaces is cracking
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and delamination of the tiles caused by movement and expansion of the timber, and something called
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surface deflection. Surface deflection is defined as a surface's vertical change in distance as a
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result of an applied, either static or dynamic load. Imagine the surface is a straight line
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and a weight or load is applied over an area of the floor - now deflection is measured as
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the distance the surface moves or deflects from its original starting point. Now while there is
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no standard test for testing surface deflection, there are rudimentary ways of observing deflection
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in a floor surface. For example jumping up and down on the surface and observing and
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feeling the flexing underfoot, listening for creaking noises, or seeing if objects on the
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floor vibrate or move. All these would indicate a level of deflection in the surface. So how to deal
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with timber floors and reduce surface deflection before tiling? Well one of the most common and
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accepted ways to nullify the effects of timber expansion, movement, and surface deflection, is
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by installing CTU or cement tile underlay. Often available as a standard six millimetre compressed
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fibre cement sheet, it's laid perpendicular to the direction of the timber flooring,
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and nailed directly to the timber. It provides added rigidity to stabilize the surface, reducing
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deflection by acting as a buffer absorbing any minor shifts in movement in the timber.
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Furthermore it provides a compatible surface for tiling and is moisture resistant. Interestingly
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particle board flooring manufacturers are shifting away from recommendations for direct tiling,
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and recommending the installation of tile underlay. For older structures with strip flooring
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or floorboards, the process of shoring and strengthening the surface may be a little bit more
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involved. Checking and replacing damaged or rotted joists, attending to moisture related issues,
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installing extra joists and bracing, are just some of the ways this can be done. Oftentimes laying of
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CTU is just not sufficient over older floors when considering the anticipated loadings and traffic
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volumes, anticipated moisture exposure such as wet areas and bathrooms, and the overall longevity
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of the system. It may require the removal of existing flooring and replacement with thicker
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conventional compressed fibre cement sheeting. Allowances for movement joints and overlaid CTU,
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or conventional fibre cement sheeting, plays a critical role in localizing movement in the floor.
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Recommendations for the placement and location of movement joints is specified in the CTU, or fibre
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cement shooting manufacturers fixing details, as well as the Australian standard AS3958 for the
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installation of ceramic tiles - and it is vitally important that these recommendations are observed.
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Placement and movement joints are subject to maximum floor spans around perimeter of rooms and
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columns. It's important these movement joints are not bridged, but are carried up through the tile,
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and joints sealed with a flexible sealant. Tile size is also an important consideration,
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essentially the larger the tile the more susceptible they are to the detrimental effects
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of surface deflection. The strain on the tile is amplified across a larger surface plane, smaller
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tiles on the other hand are able to distribute the load and surface deflection more evenly, reducing
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the strain on the tile and adhesive and minimizing the risks of cracking. The AS3958 tiling standard
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specifies to the permissible deflection range for small, medium, and large format tiles,
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so again always refer to this document for details. Selecting the right adhesive is another
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crucial element for dealing with added movement and deflection experienced with timber flooring.
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S2 classified adhesives are highly deformable, designed to provide a strong surface bond while
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accommodating minor movement. And as always refer to manufacturer's recommendations and
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relevant technical data sheets for advice on tiling over different substrates. In summary
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tiling over timber floors is a viable option when acknowledging the challenges, and employing
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practical solutions and precautionary measures to ensure the longevity of the tiling system. And
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when in doubt speak to manufacturers and industry experts, follow relevant product technical data
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sheets, and be diligent in doing your research before commencing any application. If you
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found this information valuable don't forget to subscribe to our YouTube channel, and follow our
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social media for more informative videos and tips. Thank you for joining us again on this episode
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of Prep, Set, Go, if you have any questions or would like to share your own experiences
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or insights with anything we cover in our videos which we'd love to hear from you. Until next time.
