Hi everyone and welcome to another episode of
Prep, Set, Go. For those who have joined us previously we've been looking at tiling
applications on different surfaces, and in this short episode we'll be covering
tiling over painted surfaces. So, let's jump right in. Tiling over painted surfaces
is something you'll often come across, particularly in renovation projects - but can
also occur in construction - and there are many different types of paints you might come across,
including water based acrylics, PVA paints, polyurethanes, epoxies, oil based enamels, bitumen
paints, and paving paints to name a few. Now while the chemical composition, physical attributes,
and respective uses may all be different, they generally share the same common requirement
when it comes to tiling... and that is that they should be removed. So that's all for today's
episode we said it be brief, thanks for joining us. Now we're just kidding. Now let's explore
why this blanket rule of removing paints before tiling is applicable. Now firstly unless otherwise
specified, paints are generally not designed to carry any loadings, they are standalone finishes
designed to support their own weight. Tiling systems that include the weight of the tiles,
adhesive, and grout, add significant strain on the paint to support these additional loadings
when they simply haven't been engineered to do so. So there's an obvious risk of delamination of
the paint from the substrate under load. Secondly, if the paint isn't adequately adhered to the
substrate or if it has a weak adhesion profile, it could compromise the bond between the tiles and
the substrate. Because remember the strength of the tile bond is reliant on adhesion of the paint
to the substrate, and not the tile adhesive to the paint. Thirdly, glossy or oil- based paints tend
to have a low porosity, making them inherently difficult to adhere to. This impacts the chemical
or physical bond of the adhesive to the paint and increasing the likelihood of the adhesive and
tiles to de-bond. Special primers and roughening of the surface may assist to achieve a key,
but there are still the other points we've just covered to consider. Compatibility of the adhesive
with the paint must also be considered. Can the alkaline nature of the tile adhesive chemically
affect breakdown or weaken the paint? Similarly with water-based acrylics and PVA's, these have
very low water tolerance - so contact with the wet tile adhesive could result in peeling,
softening, and breaking down of the paint, and again the delamination of the tiles. So in
summary, whenever faced with a painted surface to be tiled, understanding and evaluating the
associated risks would demand that removal of the paint back to a surface more suited and capable
of supporting the adhesion of the tiled finish to be the more safer and prudent option. Sure
it may require more work and added preparation, but will eliminate potential risk and
ensure the integrity and longevity of the tiling system. Thanks for joining us on this
episode, keep your feedback and comments coming, we love hearing from you. And remember to
like and subscribe, we'll see you next time.
