How do I adjust bifold doors so they close flush?

A bifold set is a chain, and a chain is only as square as its first link. A common experience is spending an hour on the last leaf, where the gap is obvious, when the error was introduced at the first hinge. Adjusting from the hinge end outwards is not a preference; it is the only order that converges.

Safety

What you'll need

• The manufacturer's adjustment guide if you can find it (optional)
• Hex keys and Torx bits
• A long spirit level
• A helper to hold leaves
• Dry PTFE spray

Step by step

1. Identify the system before touching anything.Aluminium, uPVC and timber bifolds use different hinge and carrier designs, and internal bifolds are different again. Look for a maker's name on the track, the carriers or the hinges, and find the adjustment guide. Turning unknown screws on a bifold wastes an afternoon.
2. Clean and check the tracks first.Vacuum the top track and the bottom guide channel. Grit in a bottom guide will hold a leaf out of position no matter how it is adjusted, and the symptom looks exactly like a hinge problem.
3. Note the current settings.Mark every adjuster with a fine marker before moving it, and write down every turn. Bifold adjustment is interdependent and being able to get back to the start is genuinely valuable.
4. Set the first leaf first.The leaf hung at the hinge end, on the frame. Get it plumb in both directions and set its gap to the frame correctly. Everything downstream inherits this. Do not move on until it is right.
5. Use the adjustments in order: height, lateral, compression.Most bifold hinges adjust in three axes like a uPVC door hinge. Set the height so the leaf hangs level and the top and bottom gaps are even, then the lateral position so the leaf sits the right distance from its neighbour, then compression so the seals meet without a fight.
6. Work outwards leaf by leaf.Once the first leaf is right, set the second to the first, the third to the second, and so on. Check the gap between each pair down its full height at each stage.
7. Adjust the top carriers for the running height.The carriers in the top track usually have their own height adjustment, separate from the hinges. This sets how the whole set hangs relative to the track and is what you use if every leaf is uniformly high or low.
8. Check the bottom guides.The pin or wheel at the bottom of each leaf must sit in its channel through the full travel. A guide that jumps out at one point means the leaf is out of plumb or the channel is obstructed at that point.
9. Set the lock and shootbolts last.The traffic door's lock and the shootbolts on the other leaves are set after the geometry is right. Adjusting geometry to suit a lock is how people end up with a set that locks and does not close flush.
10. Test the whole cycle repeatedly.Fold and unfold the whole set a dozen times, closing and locking each time. Bifolds behave differently under motion than they do held still, and a set that closes when placed gently will fight when it is swung.
11. Lubricate and record.Dry PTFE on the tracks and carriers, a little light oil on the hinge pins. Then write down what you changed and by how much, for next year.

Common mistakes

• Starting at the leaf with the obvious gap — That leaf is showing you the accumulated error from every hinge before it. Correcting it there fights the geometry and never holds.
• Turning adjusters without knowing the system — Bifold hinges vary widely and some screws are fixings rather than adjusters. Backing off a fixing screw on a loaded carrier is how leaves come down.
• Adjusting to make the lock engage — The lock is the last thing set, not the first. A geometry adjusted to suit a lock leaves the seals uneven and the leaves out of parallel.

Questions people ask