The frame is very sturdy.  We are using it with a box spring and mattress.  The directions to put it together seem complicated at first, but if you lay out the parts as directed by the diagram, it is very simple to put together.  It really is made for a carpet underneath.  We have it on hardwood floors, with carpet pieces to protect the floor.  We were sick of the bases with legs that bent.  This base will be used forever somewhere after our life!