HandyDeck tiles have inbuilt connecting tabs on all four sides which lock each tile securely to the adjacent tiles.  So once the tiles are locked in place they cannot move.

The tiles also weigh between 3 1/2 pounds and 7 pounds each, depending on the type of tile, and this weight, together with the friction between the plastic base and the surface underneath the tiles, inhibits any movement of the tiles.

\Furthermore, in the majority of situations the tiles are laid between boundary walls or laid up against railing posts which again prevents any movement.