Deck tiles are designed to install as a floating surface. Instead of using hardware to attach the tiles, the tiles use built-in features that allow them to lock together at the edges. Once connected, the tiles sit on the surface without being secured to it, making installing tiles on a concrete surface possible. However, before you install deck tiles over uneven concrete, you should even up the concrete to prevent the tiles from cracking during use.
Mark all of the uneven spots in the concrete. Ensure that spots in the floor are actually uneven and don't just appear uneven, by laying a level over the floor in any area that looks uneven. Draw a circle around each uneven spot.
Apply levelling compound with a putty knife to each uneven spot that you marked on the floor. Place the edge of a wood board against the floor on one side of the uneven spot once the spot has been filled and pull the board across the floor's surface to skim off excess compound.
Keep the concrete protected from rain and traffic for roughly 24 hours to allow the levelling compound to dry completely. After 24 hours, lay a level on the filled spots to ensure that they do not sit above the concrete's surface. If the filled spots do sit higher than the concrete surface, use medium-grit sandpaper to sand the spots down to level.
Sweep the concrete surface with a broom to remove sanding dust. If there are any areas of the concrete that appear greasy or dirty, use a wet mop to clean these spots and let the concrete dry fully before laying tiles.
Start in the corner of the concrete surface over which you want to install deck tiles. Put the first tile down in the corner and place the next two tiles on each exposed edge of the first tile, pushing the connecting pins on the tiles into the connector tabs on the edges of the first tile. Continue across the concrete surface, connecting the pins and tabs of the deck tiles together as you lay each tile to secure the tiles to each other.
Cut tiles down to fit into your tile deck design as necessary. Use a handsaw to make cuts.