My kitchen/dinner floor is concrete with the kitchen area tiled. The dinner area is to be carpeted and so i will need to fit a connector rod between the two. How should i fix this rod to the concrete floor - my limited experience of masonry nails is that they just crumble the concrete away rather than provide a good fixture. Have i previously been using the wrong masonry nails (how big should these be?). Or is there a better way of fixing these rods?