How to check if object is inside another

Im creating a city building game, and i need to check if the building is 100% inside the grid, which is currently a 3d cube (using only the X and Z coordinates of the building) i thought to take the maximum coordinates of the cube and calculate it with the construction coordinates (like the example below) in a autmotatic way that i dont need to do this for every single construction. But i dont know if this will work and i dont know how to do this. Some help ?186413-grid.png

You basically want to use a Rect struct (built-in to Unity) for each of those buildings that represents its 2D position on the grid and its height/width. You only need to check that the bottom left corner of the building is greater than the bottom left corner of the grid, and the top right corner of the building is less than the top right corner of the grid. You can decide that a building’s position is its bottom left corner, to make it very easy to do these calculations:

 public bool BuildingIsInsideBounds(Rect buildingRect, Rect gridRect)
      return buildingRect.x > gridRect.x && //left side is inside
             buildingRect.y > gridRect.y && //bottom side is inside
             buildingRect.x + buildingRect.width < gridRect.x + gridRect.width && //right
             buildingRect.y + buildingRect.height < gridRect.y + gridRect.height; //top

Actually, Rect has some functions built in that you can use to make it even simpler if you want.