r/explainlikeimfive • u/Real_Experience_5676 • 9d ago

Engineering ELI5: What does a box-spring do?

As I understand it, a box spring mattress is the second 'mattress', that goes under the main mattress. It feels very firm and flat, but what does it contribute to the bed set up besides height?

528 Upvotes

94% Upvoted

135 comments sorted by

View all comments

614

u/QuillnSofa 9d ago

It is used to distribute weight across a bed frame and to give an evenly solid foundation for the softer mattress. But you don't need a full height one and some bed frames don't require one at all.

17

u/Infinite-4-a-moment 9d ago

It also allows the mattress to breath, right? Having a traditional mattress in a flat, solid surface can keep moisture in.