How do I stop a pocket door from swaying in the opening?

The pocket door wobbles side to side as you pull it out of the wall. It taps the casing, rattles when the furnace kicks on, and never sits flat in the opening.

What causes it

A pocket door hangs from a track in the header and rolls into a cavity inside the wall. There is no floor track under it, because a floor track would sit in the doorway. That leaves the bottom of the door unsupported, so the door is free to swing between the two faces of the opening. The wider the door, the more it moves.

How to fix it

1. Pull the door most of the way out and look at the bottom of the jamb on both sides, at the mouth of the pocket. If there is nothing there, that is what is missing.
2. Get a Pocket Door Guide. It is sold in pairs, one bracket per side, and it mounts on the jamb so nothing sits in the doorway.
3. Hold the first bracket against the jamb at the point where the door leaves the pocket, close enough that it just clears the door face. Mark the slotted holes.
4. Fasten it, leaving the screws slightly loose so the slots can still move.
5. Repeat on the other side of the door.
6. Slide the door in and out. Adjust each bracket up or down in its slots until the door runs straight without dragging on either bracket, then tighten both.

When the answer is not a guide

• The door drags on the floor or the carpet. It hangs too low for the finished floor. Raise it at the hangers, or trim the bottom. A guide will not lift it.
• The door binds partway into the pocket. Something inside the cavity is in the way, or the header track is out of level. Open the pocket and look before adding hardware.
• The door jumps off its hangers. That is the track and the rollers. Fix those first, then fit the guides to keep the bottom in line.