The knobs on all my bifold closet doors are loose and spin around.

The knob is mounted in an aesthetically pleasing position in the middle of the door. The problem is that the door is hollow at this point, so any attempt to tighten the screw from the back of the door just makes both sides of the door bend inwards towards each other.

I need a way to stabilize the knob without bending/cracking the door's surface.

Knob is loose and rotates

  • 1
    maybe try a little locktite on the threads and a star washer on the back under the screw head. Commented Mar 9, 2013 at 23:49

2 Answers 2


Polyurethane Foam. The type that is used for insulation.

  1. Remove the door, remove knob and screw
  2. Tape rear hole to contain foam.
  3. Lay door flat
  4. Enlarge knob hole to allow dispensing wand to fit. (If this enlargment is too close to the knob base size, this method won't work)
  5. Dispense foam into hole. Probably a 3-4 second burst will be enough
  6. After curing overnight, redrill the hole to allow screw to pass.

This works because the foam will keep the hollow walls from collapsing


You could use a putty or other hardening product injected into the hole. Once it has hardened you will be able to tighten the screw without pulling the two sides of the door against each other.

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