Although a well laid concrete floor provides a stable and solid surface, it isn’t the nicest thing to look at or walk on. Even when used outside, it is often covered by decking, gravel or slabs. In rooms such as kitchens and bathrooms, a smooth concrete floor provides just about the best possible surface to tile over. Tiles are hard-wearing and easy to keep clean. They prevent spills from soaking through to the sub floor and, if laid correctly, will not harbour germs and stains (nor the smells they can produce.)
Preparing the Floor
Tiling a concrete floor is, if planned and prepared for, a fairly easy task. It is important to make sure that the floor is clean, dry and level, as well as making sure that it is in good overall condition. If there are cracks or holes in the floor, these should be filled with an appropriate mortar mix and allowed to dry before continuing.
Clean the floor thoroughly, removing any old paint, sealants or oil. Sweep and then hoover the floor to remove dust and debris, and then wipe it down with a damp mop to pick up the finer dust particles. Allow it to dry completely before you start to apply adhesive. If the concrete is very smooth, it is worth using a manufacturer-recommended acid-based solution to roughen it slightly. This will allow the adhesive to form a stronger bond to the floor.
Planning the Layout
Measure the mid point of all four walls and then draw lines between the four marks to form a cross. This should give you the mid-point of the floor and is the best place to start laying the tiles. If you are planning on creating a pattern with your tiles, lay them out dry first to see if the pattern looks right. You can either start by placing a single tile on the very centre of the crossed marks, or you can place one tile into each of the right angles where the lines meet.
Spreading the Adhesive
When tiling onto a concrete floor, it is possible to use a non-flexible adhesive. Make sure that you buy floor tile adhesive, as this will be water-resistant. Adhesive designed to be used on walls isn’t always water resistant, unless it is designed for bathroom walls. Flexible adhesive can also be used when tiling over a concrete floor if you wish.
Tile adhesive is available in two main types: Normal and Rapid Set. Rapid set adhesive will obviously allow you to finish the room faster (you could be applying grout within a few hours of laying the tiles) but normal set adhesive allows a bit more room for error. If you have never laid tiles before, we would suggest going for the normal set adhesive. If using powdered adhesive, mix up small quantities at a time.
Using a notched spreader (often provided with the adhesive), apply the adhesive over about one square metre of the floor. Follow the instructions on the adhesive so that you get the correct depth to the grooves. When the whole of the square metre is spread, you can start to lay the tiles.
Laying the Tiles
Lay the first tile at your centre point. Press the tile firmly down into the adhesive, giving it a slight twist to make sure there is a good bond. Lay the second tile, using the correct spacers along the edge where the two tiles meet. Continue to lay tiles, radiating out from the centre. Mix and apply more adhesive in roughly one metre square areas as required. When you have laid all of the full tiles, you should be left with a border around the room where tiles will need to be cut to fit (unless you are incredibly lucky and the last full tiles fit exactly against the skirting).
Allow the tile adhesive to set overnight before you cut and lay the border tiles around the edge of the room. Once the border tiles are laid, allow these to set for the same amount of time.
Grouting the Floor Tiles
Remove all of the tile spacers and mix up the grout, following the manufacturers instructions. Apply the grout to the joints using a flexible rubber spreader or float. Press the grout into the joints at an angle and then run a blunt round object (something like a pen lid) along the joint to give the grout a nice finish.
Before the grout fully dries, wipe away the excess with a damp sponge and then buff the tiles. Allow the grout to dry fully for a couple of days, without walking on the floor during this time. Seal the gap around the edges of the room using a waterproof caulk. Let this dry and then sweep and wipe the whole floor. You should now have a perfectly tiled concrete floor.