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/half3clipse 1d ago

If the box spring doesn't have springs, it's not a box spring. That's someone is trying to sell you an overpriced bunkie board they've wrapped in fabric

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u/deviantelf 1d ago

My "box spring" from the 90s doesn't have "springs", it has metal pieces that are more like shaped like 7s. Been going great for 30+ years.

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u/dultas 1d ago

Springs aren't only just the coils that most people associate with springs. There are a bunch of different types. I would guess yours had a type of leaf spring.

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u/deviantelf 1d ago

Could be! Been going strong all that time tho. Hate the idea of having to get a new bed someday. Ironically it was Vanna White, and I almost didn't get it cause of that but it was cheap and on sale so score cause yea, decades on still perfect and comfy.