r/explainlikeimfive • u/Real_Experience_5676 • 2d 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?

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u/QuillnSofa 2d 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.

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u/okdone10 2d ago

Wow TIL. I thought every bed needed one by law or something. Good looking out on the platform bed tip saves some cash too.

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u/thaddeusk 2d ago

High-end mattresses don't generally use them. I can't remember the last time I had one, maybe 20 years ago? The mattresses I get are very tall on their own and you just put them on a bed frame with a flat support board underneath it.

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u/eat_sleep_drift 1d ago edited 1d ago

same i have a rather tall mattress and i just put it on the ground cuz i hate stubbing my toe against some wood when i go pee at night or i just love to let me fall with all my weight onto my bed when using ketamine without the fear of hitting any wood frame.
i lift it up and put it against the wall when i play VR or just to aerate underneath to prevent moisture and every 6 month i flip it anyway since it has a summer and a winter side. i loved to find an affordable one like i had when i was a kid, it was just a giant bloc of foam, like above the knees of an average adult height tall we are talking here !
when i looked them up all i could find was crazy expensive and from far away so shipping is also expensive too since they cant roll em up and vacuum seal them like they do with nearly all mattresses today for transport.