A pair of full-length interlined curtains on a large window can weigh 15kg or more. That is a serious load hanging off two small brackets, and it is the reason most curtain pole failures happen. The good news is that hanging heavy curtains properly is straightforward once you know what to look for.
First, work out what they weigh
People consistently underestimate this. If the curtains are already made, weigh them on bathroom scales — it takes a minute and removes all the guesswork.
If they are not yet made, a rough guide: a lightweight unlined cotton curtain might be 2–3kg a pair. Lined cotton or linen, 5–8kg. Interlined velvet or heavy blackout on a tall window, 12–20kg. Interlining in particular adds far more weight than people expect.
Choose the pole diameter for the load
Diameter is the single biggest factor in how much weight a pole carries.
- 19mm — lightweight curtains, narrow windows only.
- 28mm — the standard size, fine for most lined domestic curtains.
- 35mm and above — what you want for interlined, blackout or velvet curtains, particularly on a wide window.
Metal carries more than timber at the same diameter. If you want the appearance of wood with a heavy load, go up a size.
Add a centre bracket
This is the step most often skipped, and the most important one. Any pole over roughly 200cm should have a centre bracket. Over 300cm, use two.
The usual objection is that the bracket will block the curtains from drawing across. It will not, if you use a passing bracket — designed so the rings pass over it rather than stopping against it. Standard centre brackets do obstruct the rings, so specify passing brackets when the curtains need to draw fully.
A centre bracket does not just prevent sag. It roughly doubles the load the pole can take, because it halves the unsupported span.
The fixings matter more than the pole
Most failures are not the pole breaking. They are the brackets pulling out of the wall.
Into solid masonry — brick or block — use good quality wall plugs with screws long enough to get at least 50mm into the masonry itself, not counting plaster depth. Plaster can easily be 15mm, so a 50mm screw may barely reach the brick.
Into plasterboard — this is where care is needed. Plasterboard alone will not hold heavy curtains, no matter which plug you use. Find the timber studs or the noggin above the window with a stud detector and fix directly into timber. If there is genuinely no timber where you need it, fit a timber batten across the studs first and mount the brackets onto that. Heavy-duty plasterboard anchors exist and are fine for light curtains, but do not rely on them for an interlined pair.
Into lintels — steel lintels above windows cannot be drilled conventionally. Fix above or to the side of the lintel, or use self-drilling screws rated for steel.
Check the whole chain
A heavy curtain is only as secure as its weakest component. Look at the rings — thin rings can distort under load. Check the finials are properly secured so rings cannot slide off the end. And make sure the heading tape and hooks are rated for the weight; standard plastic hooks can open up under a heavy load, so use metal hooks for interlined curtains.
When a track is the better answer
If the curtains are genuinely very heavy, a heavy-duty track may serve you better than a pole. Tracks distribute weight across many brackets rather than concentrating it at two or three points, and a corded heavy-duty track will draw far more smoothly than heavy curtains on rings.
You can have both looks: a pole with an integrated track gives you the appearance of a traditional pole with the load-spreading and smooth draw of a track behind it.
If in doubt
Over-specify. The difference in cost between a 28mm and a 35mm pole is small. The cost of a pole coming out of the wall — damaged plaster, torn curtains, possibly a broken window — is not.