If your decorative bed frame is panel style, you need a Flat Foundation. Bed frames are either panel or platform style. Panel frames typically have a cross-slat support system, meaning there are 3-5 horizontal slats with gaps 15-35 inches in length, requiring the use of a box spring or flat foundation for adequate support. In contrast, platform frames have slats with less than 3.5" gaps or a completely solid surface and thus provide sufficient support on their own for a mattress.