Just read (Top cover design) link. I AM AMAZED! The beek questioned using a flat top cover because his top bars are only 3/16 below the hive top. We have been getting so many poorly made boxes from suppliers for so long that no one knows what the proper demensions are! The bottom board has a 3/8 inch rim. Right! The bottom bars of the first box should be flush with the bottom of the box. That gives you 3/8 bee space at the bottom board. Right! If the frames are flush with the bottom of the box, you will have 3/8 inch between the top of bars and top rim of the box. Every box should be the same.
RECAP! Proper beespace. Bottom bars flush with bottom of box! Top bars 3/8 below top rim of box.