Curtains are one of the few things in a room that everybody sees and almost nobody inspects closely, which is precisely why the errors show up so clearly. A stripe of daylight above the track, a hem that stops in an awkward place, fabric that hangs as flat as a bedsheet: each one quietly undermines an otherwise finished room. The reassuring part is that most curtain problems come from a small handful of repeated mistakes, and most of them can be put right without ordering everything again.
Mistake 1: Mounting the Track in the Wrong Place
The single most common error is fitting the track or pole tight against the top of the window frame. It feels logical — the frame is there, the brackets fit — but it shrinks the window visually and drags the whole wall down with it. Hang the track as high as the room allows instead, ideally within a few centimetres of the ceiling or the underside of any cornice. Drawing the eye upwards makes ceilings feel taller, and it gives you room to hang full-length curtains that skim the floor.
Width matters just as much. A track that stops at the edges of the recess forces the open curtains to sit across the glass, blocking light and hiding the view you presumably bought the window for. As a rule of thumb, extend the track roughly 15–20cm beyond each side of the recess. When the curtains are drawn back, they stack neatly over the wall rather than over the window.
If moving the track isn't possible — a concrete lintel, a listed interior, a landlord who won't thank you — you can disguise a low fitting with a fabric-covered pelmet or a simple valance. Choose a drop that clears the frame generously so the gap reads as deliberate rather than accidental.
Mistake 2: Ending Up with the Wrong Drop
Curtain length is where small numbers make a big difference. A hem that lands a few centimetres above the floor looks like a mistake; the same hem sitting 1cm above the floor looks tailored. Equally, curtains that end halfway down a radiator, or exactly at the sill when everything else in the room is floor-length, chop the room into horizontal bands.
Ready-made curtains usually come in standard drops, which is convenient but also how people end up with the wrong one. Work in this order:
- Fit the track or pole before you measure anything. Everything else depends on it.
- Measure from the point the hook or ring will actually sit — the top of the heading tape, the bottom of a ring, the top of an eyelet — not from the top of the fabric.
- Decide where the hem should land. Just below the sill, about 10–15cm below it, or floor-length are the three that work most often. A slight puddle of 2–3cm suits relaxed, romantic rooms; skip it in busy hallways or anywhere a hoover goes.
- Add a hem allowance — 10cm is generous enough to let a curtain maker or a competent sewer level the hem on the wall, where floors and ceilings are rarely perfectly square.
If you're between sizes, buy longer. Taking fabric up is straightforward; adding it is not.
Mistake 3: Underestimating How Much Fabric You Need
Curtains need roughly twice the width of the track to look properly dressed, and pencil pleat and pinch pleat headings often want closer to 2.5 times. That means a 200cm track needs somewhere between 400cm and 500cm of fabric across both panels. Skimp on this and the curtains will hang in a few limp creases, refuse to stay closed, and let light leak through the middle.
Ready-made pairs are the usual culprit. The width on the packet is per panel, measured flat before the heading is gathered, so a "pair" advertised as generous can still look thin once the tape is pulled up. If you already own curtains like this, you have options: draw them tightly and set the pleats by hand, pair them with a sheer layer behind, or move them to a narrower window where the fabric will finally have somewhere to go. For a wide window, adding a matching third panel is often cheaper than replacing the lot.
Mistake 4: Choosing a Heading That Doesn't Suit the Track
Heading styles and hardware are not interchangeable. Eyelet curtains need a pole, ideally a slim metal or wooden one, because the rings are built into the fabric. Pencil pleat and pinch pleat work on tracks and poles alike. Rod-pocket curtains, where the pole threads through a sewn channel, should fit snugly — a loose pocket makes the curtain hang in a slack curve. Wave headings need specific gliders and a track long enough to let the folds stack back cleanly.
The quieter error is hook placement. On a pencil pleat heading, the three rows of pockets change the drop by several centimetres: the top row gives the longest curtain, the bottom row the shortest. Decide which row you're using before you measure for the hem, and be consistent across both panels, or you'll end up with one curtain sitting lower than the other.
Mistake 5: Leaving the Finishing Details Until Last
Weights, returns and lining are the details nobody notices until they're missing. Small weights sewn into the bottom corners persuade a hem to hang straight instead of curling; without them, thin fabrics flare outwards and look unfinished. At the sides, the curtain should return gently back towards the wall rather than hanging in mid-air, which stops light spilling round the edges and prevents that floating look.
Lining does more than block light. It protects fabric from sun damage, adds body, and improves how the folds fall. And once the curtains are up, steam them on the rail rather than fighting with an iron — hanging them, then training the folds by hand every day for a week or two, will settle the pleats far better than anything else. If you plan to shorten them, live with them for a fortnight first. Most curtains drop slightly as the fabric relaxes.
Quick Fixes You Can Make This Weekend
- Light leaking above the window? Raise the track, or add a pelmet if you can't.
- Curtains blocking the glass when open? Extend the track by 15–20cm on each side.
- Hems hovering? Take them down, level them on the rail and re-hem. Work with the curtain hanging, not on a table.
- Flat, mean-looking folds? Pull the heading tape tighter and space the hooks further apart, then dress the folds by hand.
- Hems curling? Add curtain weights to the bottom corners and sides.
- Creased panels? Hang them and steam in place; give the fabric a week to fall.
The Right Order to Work In
Curtains go wrong when they're treated as the last five minutes of a decorating job. Do it the other way round and most of these mistakes disappear before they happen: fit the track or pole, decide the drop, order enough fabric, choose a heading that matches your hardware, then hang, steam and dress. It takes an extra hour of planning, and it's the difference between curtains that merely cover a window and curtains that finish a room.
