How do I fit flat-pack drawers so they run smoothly and sit level?

A drawer that sticks is almost never a faulty drawer. It is two runners that are not parallel, and they are not parallel because the carcass is not square or because the two sides were marked independently. Everything in this job is about transferring one measurement to both sides rather than making the same measurement twice.

What you'll need

• Drawer kit with runners, or replacement runners
• Screwdriver or a driver on low torque
• Small spirit level
• Tape measure and a square
• Bradawl for starting screws (optional)
• 2mm packers or coins, for setting front gaps (optional)

Step by step

1. Square the carcass before a single runner goes in.Measure both diagonals. If the sides are not parallel, no amount of care with the runners will produce a drawer that runs, because the two runners cannot be parallel inside a carcass that is not.
2. Mark the runner heights on both sides from one gauge.Cut a scrap of board or card to the height of the first runner and use it against the base to mark every runner position on both sides. Measuring each side independently introduces exactly the small errors that cause binding.
3. Set the runners back from the front by the drawer front thickness.Most systems want the runner set back so that the drawer box closes flush and the front then sits proud. Check the instruction sheet — this is the dimension that is model-specific.
4. Fix the front screw first, level the runner, then fix the back.Runners have slotted holes for exactly this reason. Front screw snug but not tight, level the runner, back screw, then tighten both.
5. Fit the drawer box and test before adding any more.It should run with a fingertip and close without a shove. Work out the first drawer completely, then use it as the pattern for the rest.
6. Check both sides engage before pushing.Most side-mounted runners hook or click in. A drawer forced home with one side unengaged bends the runner permanently.
7. Fit the drawer fronts last, with packers.Slip 2mm packers or coins into the gaps around the front, hold it in place, and screw it to the drawer box from inside. The packers hold the gap while you fix, which is far more accurate than eye and hand.
8. Use the adjustment the fittings give you.Many drawer front fixings have slotted or cammed adjustment for height and side-to-side. Set the gaps by eye across all the fronts at once, from a metre back, rather than one drawer at a time up close.
9. Load the drawers low and within their rating.Standard domestic runners are rated 15 to 25kg. A deep drawer full of tools or crockery exceeds that easily, and an overloaded runner droops permanently and then binds.
10. Anchor the unit if it is tall or top-heavy.A chest of drawers with the top drawers open puts its centre of gravity ahead of the front feet. That is the tip-over case. Strap it into a stud or masonry before it goes into use.

Tips

• A drawer that runs sweetly empty and binds when loaded means the runners are undersized or the carcass sides are flexing. Check the back panel is properly fixed.
• Rub a candle or a dry PTFE lubricant on wooden runners in older furniture. Never oil or grease a metal ball-bearing runner — it collects dust and gums up.
• If a drawer front is scribbling the one below on the way out, the runner is drooping, not the front. Check the runner is level and within its load rating.

Common mistakes

• Measuring the runner height separately on each side — Two independent measurements have two independent errors, and a 2mm mismatch is enough to make a drawer bind. Use one gauge for both.
• Fitting the drawer fronts before the boxes run properly — The fronts hide the runners and every later adjustment has to happen through them. Get the boxes running first.
• Tightening both runner screws before levelling — The slotted holes exist to let you level it. Once both are tight the runner is wherever it landed.

If it doesn't work

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