The bottom has dropped out of a drawer — how do I put it back properly?

A drawer base is a 3mm sheet held only by sitting in a shallow groove. It has no fixings on three sides by design, because that is how a drawer is assembled. The system works until the sheet bows enough to slip out of one groove, at which point the whole load is on three sides and it goes.

What you'll need

• Replacement 6mm MDF or plywood, if the base is damaged (optional)
• Panel pins or 15mm screws
• Tape measure and a square
• Saw or a sharp knife and a straight edge (optional)
• Wood glue (optional)

Step by step

1. Empty the drawer and take it out.Work on a bench or the floor. Trying to refit a base with the drawer in the unit is how the sides get racked.
2. Look at the base before deciding anything.Flat and undamaged means refitting it. Bowed, split, delaminated or swollen means replacing it — a bowed base will simply come out again.
3. Check whether the drawer box is square.Measure the diagonals of the box. A racked box has grooves that no longer line up, and the base cannot sit in all four. Push it square before refitting anything.
4. Slide the base in from the back.Almost all drawers are designed to be assembled this way: the back panel comes off or sits above the groove, and the base slides forward into the front and side grooves. Force it in from underneath and you break the groove edge.
5. Seat it in all four grooves and check the corners.Look along each edge. The base should be fully engaged everywhere before anything is fixed.
6. Fix it up into the back edge.Pins or 15mm screws up through the base into the bottom edge of the drawer back, at 100mm centres. That is the only fixing the design has and it is the one that is usually missing.
7. Cut a replacement square and slightly undersize.Measure groove to groove in both directions, and cut about 1mm under in each direction so it slides without forcing. 6mm MDF or plywood rather than 3mm hardboard — twice the thickness is roughly eight times the stiffness.
8. Deepen or reinforce the groove if it has broken away.Where a chipboard groove edge has crumbled, glue a timber bearer along the inside face of the drawer side at the groove height and let the base sit on that instead. It is a permanent fix and it is invisible when the drawer is closed.
9. Add a centre support on a wide drawer.Any drawer over about 600mm wide benefits from a timber rail glued and pinned across the underside, front to back. It stops the base bowing, which is what caused this in the first place.
10. Reload it with the weight limit in mind.The base and the runners both have limits. Heavy items low in the unit and spread across the drawer, not stacked in one corner.

Tips

• If a drawer base has dropped once, the drawer is being asked to carry more than it was designed for. Move the heavy contents to a lower drawer or a different piece of furniture.
• A base cut from 6mm plywood, glued into the grooves as well as pinned at the back, will outlast the rest of the drawer.
• Take the old base with you as a template if you can — but check it is square first, because a bowed old base is often also the wrong shape.

Common mistakes

• Nailing the base up into the drawer sides from underneath — The sides are thin chipboard and the pins split them. The base is meant to float in the grooves and be fixed only at the back.
• Refitting a bowed base — It will slip out of the groove again, usually within weeks. The bow is the fault, not the fixing.
• Cutting a replacement to the exact groove-to-groove dimension — It will not go in without forcing, and forcing breaks the groove. Cut about a millimetre under in each direction.
• Gluing the base into all four grooves on a solid timber drawer — The base needs to move slightly with humidity in timber furniture. Pin it at the back and let it float.

If it doesn't work

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