CARE AND FAQ How deep are the shelves? The shelves are 17.5 cm deep. Is it glued or screwed? No, it is just held by the wedges. Do I need to fix it to a wall? Yes. Wall Shelving System comes included with fixing brackets. These should be installed at the top, bottom and at every leg interval. How do I know that the shelf is straight? By using a water level, a water level app or measuring the dista