Why is my curtain pole sagging in the middle?

Curtains are far heavier than people expect. A pair of lined, interlined curtains across a large window is easily 8 to 12kg, and all of it hangs from a tube supported at two points. Sag is the same arithmetic as a shelf: it rises steeply with the span, so the fix is a support in the middle rather than a stronger pole.

What you'll need

• Centre support bracket to suit the pole diameter
• Drill and fixings for the wall above the window
• Cable and pipe detector
• Long spirit level
• Timber batten, if there is nothing solid to fix to (optional)

Step by step

1. Weigh what is on it.Take one curtain down and put it on the bathroom scales. Lined curtains for a typical window are 3 to 6kg each; interlined or velvet ones considerably more. The number usually explains the sag on its own.
2. Check whether the centre bracket was ever fitted.Most poles over 1.5m are supplied with one. It is the part most often left in the packaging because the pole looked fine on the day it went up.
3. Fit a centre support, and get the right kind.There are two types: a cradle that the pole rests in, which carries load, and a light retaining bracket that only stops the pole rolling. For sag you want the load-carrying kind, and it must be set at the same height as the end brackets so it actually takes weight.
4. Fix the centre bracket into something solid.The middle of a window head is often exactly where there is a steel lintel or a plasterboard void. If there is nothing to fix to, a timber batten across the full window width, screwed into the masonry each side of the opening, gives you a fixing anywhere along it.
5. Scan before drilling, as always above a window.Cables run horizontally above windows to light switches. Scan the whole line, and stop if the reading is ambiguous.
6. Check the end brackets have not moved.A pole that has dropped at the middle sometimes has ends that are pulling out rather than a bowed tube. Look for gaps opening behind the brackets and plaster dust below the screws.
7. Judge whether the pole itself has set.Take the curtains off and lay the pole on a flat floor. A metal pole often springs back. Timber and thin hollow poles frequently do not — they creep under sustained load and the bow becomes permanent.
8. Replace with an adequate pole if it has bowed.28 to 35mm diameter steel for a heavy or wide window, rather than 19 to 25mm. Wall thickness matters as much as diameter, so a solid or heavy-gauge pole beats a wide thin one.
9. Split a very wide window into two poles.Two poles meeting at a centre bracket, with a curtain on each, is the standard answer over about 3m. It also makes the curtains manageable to handle and to wash.
10. Reduce the load if nothing else works.Unlined or lighter curtains, or a track rather than a pole. A ceiling-fixed track carries weight along its whole length and does not sag at all.

Tips

• A pole that sags only when the curtains are drawn closed is fine; sag with the curtains open at the sides means the pole itself has taken a set.
• Rings bunched at the centre for storage over summer put a point load exactly where the pole is weakest. Push them to the ends.
• For very heavy curtains, a track fixed to the ceiling or to a batten across the whole window head is a better system than any pole. It supports continuously rather than at two or three points.

Common mistakes

• Buying a longer pole rather than adding a centre bracket — Sag depends on the span between supports, not the pole length. A longer unsupported span is worse, not better.
• Fitting the centre bracket lower than the ends — It then does nothing until the pole has already bowed down to meet it. All three brackets on one level line.
• Using a retaining clip as a centre support — Some centre fittings only stop the pole rotating and carry no load. Check that the pole actually rests in it.
• Fixing a centre bracket into plasterboard above the window — That is exactly where there is often a void or a steel lintel. Find the structure, or fit a batten across the opening.

If it doesn't work

Questions people ask