Why will my French doors not meet in the middle?
Telling a dropped leaf from a bowed one and from a frame that has moved, and correcting each — plus the seasonal version of the fault that needs no correction at all.
- Difficulty
- intermediate
- Time
- 1 hr
- Read
- 4 min
- Safety
- caution
Short answer
Close each leaf on its own and look at its gap to the frame. If each is fine alone but they clash in the middle, the frame has narrowed or a leaf has bowed. If one leaf's gap is tapered, that leaf has dropped and needs raising at its hinges. Correct the slave leaf first, always.
French doors present two leaves that have to meet accurately down a two-metre line, with no fixed post between them. Everything that moves — the leaves, the frame, the lintel above — shows up at that centre joint, which is why it is the first place a problem appears and why the problem often looks worse than it is.
Safety
Step by step
- Test each leaf on its own.Open both, then close only the slave leaf and look at the gap all round it. Then open it and close only the master. This separates a leaf problem from a meeting problem in about thirty seconds.
- Read a tapered gap.If one leaf's gap is wide at the top and tight at the bottom on the closing edge, that leaf has dropped on its hinges. If it is tight at the top of the hinge edge, it has racked. Either way the correction is at that leaf's hinges.
- Correct the slave leaf first.The slave leaf is effectively the frame that the master closes against. Get it plumb, correctly gapped and bolted home before touching the master. Adjusting the master to suit a wrong slave is the classic wasted afternoon.
- Raise a dropped leaf at the hinges.On uPVC and composite French doors the hinges adjust for height, lateral position and compression, exactly as on a single door. Work in quarter turns across all three hinges rather than winding one to its limit.
- Check for bowing rather than dropping.Hold a long straightedge or a taut string down the closing edge of each leaf. A leaf that is straight has an alignment problem; a leaf that is visibly bowed in the middle has a different problem, usually heat on a dark door or a timber leaf that has taken up moisture.
- Check the frame and the lintel.Measure the frame opening at the top, middle and bottom. A frame that is narrower in the middle than at the ends has been squeezed, which on a wide opening usually means the lintel above has deflected. That is a structural question and adjustment will not solve it.
- Check the shootbolts are fully home.A slave leaf whose top or bottom shootbolt is not fully seated will move under the master's pressure. Throw the bolts and try to move the leaf by hand at the top and bottom — it should be solid.
- Check the keeps on the slave leaf.On uPVC and composite French doors the master's hooks lock into keeps on the slave leaf's edge, not into the frame. Those keeps are adjustable and they move as the leaf sags. They are set after the leaves are right, not before.
- Accept the seasonal version.Dark uPVC and composite doors on a sunny elevation bow measurably on a hot afternoon and recover by evening. If your doors meet perfectly in the morning and clash at five o'clock in July, do not adjust them — the adjustment will be wrong all winter.
- Recheck the whole cycle.Slave closed and bolted, master closed, handle lifted, key turned, then all of it reversed. Do it a dozen times. Anything that needs a shove will fail in cold weather.
If it doesn't work
Both leaves close individually but overlap in the middle
Cause: The frame has narrowed, or one leaf has bowed — Fix: Measure the frame at three heights and check both leaves with a straightedge. A narrowed frame is a structural matter; a bowed leaf is heat or moisture and may be seasonal.
There is a gap in the middle at the top and they touch at the bottom
Cause: One or both leaves have dropped, or the head of the frame has deflected — Fix: Raise the leaves at the hinges. If both are already at the top of their adjustment and the gap persists, look upwards at the lintel.
They meet fine but the master will not lock
Cause: The keeps on the slave leaf's edge are out of line with the master's hooks — Fix: Adjust the keeps in or out and, where the design allows, up or down. Do this only after the leaves themselves are right.
Fine all winter, clash every summer afternoon
Cause: Thermal bowing of a dark door in sun — Fix: Leave it. Adjusting for the hottest hour of the year gives you doors that rattle for the other eleven months.