At the moment we only support 3-floor buildings at Planner 5D. However, you still have an option of building a couple of additional floors, if you wish so.
1. Start with extending the wall height of the third floor by clicking on it and editing measurements in the bottom menu. We've made the height of the third floor twice as the previous two.
2. Switch to a 2D view mode and drag a Magic Cube nearby. Edit its measurements as well to turn it into a flat board. Don't forget to set an "Above" parameter to a height of the fourth floor. Since we've made the third floor 400 cm high, it is 200 cm for us to set a Magic cube as a floor of the fourth one.
3. Now you can place an edited Cube or several of them as platforms for additional floors.