Drawer Inserts Suitable for IKEA Kallax

Drawer inserts suitable for the IKEA Kallax shelving unit are based on exact internal carcase dimensions of 335 mm × 335 mm × 390 mm and require precisely matched drawer runners for smooth operation.

Retrofitting shelving compartments with drawers requires a technical understanding of the furniture's construction. Those looking to extend standard cube shelving with closed storage space need hardware that is accurately adapted to the existing geometry. This guide is aimed at fitters and experienced DIYers looking for accurately fitting fittings and runner systems as an alternative to factory inserts.

What to Consider Regarding Compatibility

A typical cube shelving unit of this design consists of lightweight panels (honeycomb core). This places special requirements on the installation of hardware. Before making any modifications, three technical parameters must be strictly observed:

1. Exact Internal Dimensions

The clear dimension of a compartment is generally 335 mm in width, 335 mm in height, and 390 mm in depth. This depth is the limiting factor when choosing drawer runners. A runner with a nominal length of 350 mm makes optimal use of the available space without hitting the back panel. Longer runners (e.g. 400 mm) will protrude beyond the carcase and are not compatible.

2. Lack of System 32

In contrast to classic kitchen carcases, these shelving compartments do not come with factory pre-drilled System 32 holes (drilled rows with 32 mm spacing and a 5 mm hole diameter). Installing drawer runners into a smooth carcase is like laying a foundation: the first drilled hole defines the stability and precise running of the entire assembly. All fixing points must be measured and pre-drilled manually.

3. Material Properties and Screw Selection

The internal walls consist of thin chipboard or hardboard with a thickness of around 15 mm. When fastening the runners, the chipboard screws (ideally with a PZ or TX drive) must not exceed a length of 13 mm to a maximum of 14 mm, otherwise they will penetrate through into the neighbouring compartment. A diameter of 3.5 mm to 4 mm provides sufficient hold in the material.

Suitable Furnica Hardware for the Conversion

Those building inserts suitable for IKEA Kallax or looking to replace defective original parts can turn to modular hardware fittings. Selecting the right components determines the load capacity and operating convenience.

Drawer Runners and Extension Types

The foundation of every drawer is the runner. A distinction is made between two main extension types: A full extension runner extends by 100%, whereas a single extension runner stops at roughly 75% of its nominal length. For deep shelving compartments, drawer runners full extension are recommended, as they ensure complete access right to the back of the drawer.

Regarding the mechanical design, several options are available:

• Ball bearing runners: These run on small steel balls, are mounted to the sides of the drawer box, and offer high lateral stability.
• Roller runners: A simple, robust mechanism using plastic rollers. They tolerate minor assembly misalignments.
• Damping: Drawer runners with soft close absorb the momentum of the closing drawer, pulling it shut silently and smoothly over the final centimetres.
• Heavy duty: If files or tools are being stored, heavy duty drawer runners can be used. Note, however, that the load rating (e.g. 30 kg) is limited by the pull-out strength of the screws in the honeycomb panel.

Attention: Never confuse soft-close with push-to-open. They are opposite mechanisms. Soft-close slows the drawer down upon closing. Push-to-open (tip-on) ejects the handleless drawer when pressed.

Complete Systems and Accessories

Instead of gluing timber drawer boxes yourself, complete drawer side systems can also be used. Modern drawer systems consist of metal sides into which only a base and a back panel made of 16 mm chipboard need to be inserted.

For the internal layout and functionality of the finished drawer, suitable drawer accessories are relevant. To prevent items from sliding around when opening and closing, the base is lined with a non-slip drawer mat. These mats can be cut precisely to the internal dimension using a utility knife.

If the shelving is used in a home office, security can be enhanced with a drawer lock. For this, a surface-mounted rim cylinder lock is fitted behind the front panel, with its striking plate engaging the shelf above. To operate the fronts, drawer handles (wall unit handles) complete the setup. For these, clearance holes (usually 4 mm or 5 mm) are drilled into the front.

Installation and Retrofitting: Step-by-Step

Installing drawers into empty shelving compartments requires precision. An uneven runner will inevitably cause the drawer mechanism to bind.

Required Tools:

• Cordless drill/driver
• Wood drill bits (Ø 2 mm for pre-drilling runners, Ø 5 mm for handles)
• Try square
• Tape measure / folding rule
• Pozi or Torx driver bits

Installation Sequence:

1. Marking out: Mark the height of the runners on the inside walls of the compartment. Use the try square to draw an exact horizontal line from the front edge to the back.
2. Setback from the front: Do not mount the runner flush with the front edge. Account for the thickness of the drawer front (usually 16 mm to 19 mm) so that it sits flush with the shelving carcase when closed.
3. Pre-drilling: Pre-drill the marked fixing points with a 2 mm drill bit to a maximum depth of 5 mm. This prevents the surface coating from chipping.
4. Runner installation: Secure the carcase runner firmly using short chipboard screws (e.g. 3.5 x 13 mm).
5. Inserting the drawer: Mount the mating drawer profile to the drawer box and assemble the parts together. Check the gap alignment.

Frequently Asked Questions (FAQ)

Which runner length is compatible with the IKEA Kallax? Since the carcase depth is 390 mm, drawer runners with a nominal length of 350 mm are the technically correct choice. Runners measuring 250 mm or 300 mm can also be installed, but they waste storage space at the back.

Can I install heavy duty runners in lightweight shelving units? Technically, fitting heavy duty runners is possible. However, the limiting component is not the steel runner, but the pull-out resistance of the screws in the shelf's honeycomb core panel. A load of over 15 kg per compartment should be avoided with this type of construction.

Can dampers (soft-close) be retrofitted to older drawers? If the existing drawers use basic roller runners without damping, they can be completely replaced with ball bearing runners featuring an integrated soft-close mechanism. The prerequisite is that the installation width (the clearance between the drawer side and the carcase wall) is identical – for ball bearing runners, this standard dimension is 12.7 mm per side.

How do I fit a drawer lock in the shelving unit? A surface-mounted lock is fastened to the inside of the drawer front. The locking bolt extends upwards. To accommodate this, a small recess must be mortised into the underside of the shelf above, or a flat striking plate must be screwed in place for the bolt to latch into.