New Simmons Box-Spring on a new Simmons King sized bed causing creases

I just discovered that the reason why my new mattress has a crease on each side with a solid middle is because of the 2 Box-Springs underneath. The Boxes seem fine but what worries me is the fact that the whole mattress is not flat. The middle part where the Box-Springs meet is slightly higher. Is this normal?


Hi mikejones,

No this is not “normal” or at least shouldn’t be happening and a split king foundation should allow you to put a sheet of wood over it for example without “rocking” in the middle. The Triton foundation that normally goes with your mattress has a wire grid which is firm and even and should not be higher in the middle (or on the sides of each twin).

Of course it’s also possible that your foundation is a different (cheaper) one with widely spaced wooden slats perhaps with cardboard over them and in this case the edges of each twin where they came together would be firm and rigid but the layers above the slats (cardboard or the mattress) could be sinking into the gaps or sagging in the middle area in which case these sags or the materials sinking into the gaps would reach the surface of the mattress while the middle area which had the two sides of the foundation under them would stay fully supported. I’ve also seen this in some foundation where the edges are higher than the slats.

Either way … it shouldn’t be happening and would indicate a problem with the foundation.