How Do You Make a Soft Mattress Hard?

Written by heather preston
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How Do You Make a Soft Mattress Hard?
Use cardboard to add firmness to a mattress. (carton d"emballage image by Unclesam from

Buyers often get caught up in the feeling of a soft mattress under them at the furniture store, only to realise it leaves them with an aching back after purchase. The good news is that there is a simple solution to add firmness to your soft mattress.

Skill level:

Things you need

  • Cardboard box
  • Utility knife

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  1. 1

    Visit your local home improvement store. Ask a store assistant for a cardboard refrigerator box. Request two boxes if you want a really firm mattress.

  2. 2

    Lift mattress off of box springs. Lean it up against a wall for support.

  3. 3

    Flatten out a cardboard refrigerator box. Lay cardboard on top of box springs. Use a utility knife to cut off excess cardboard. Fold or cut box in half if you are only adding firmness to one side of the bed.

  4. 4

    Repeat Step 3 if you are using two pieces of cardboard for additional firmness.

  5. 5

    Place mattress on top of box springs and cardboard. Make the bed as usual.

Tips and warnings

  • Use new cardboard pieces every two weeks to renew firmness. For maximum firmness, use a plywood board underneath your mattress instead of cardboard.

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