Retrofitting Shelves for IKEA Kallax
The professional retrofitting of internal shelves in modular furniture requires accurately drilled rows of holes and fittings that are mechanically compatible with the base material.
Retrofitting Shelves Suitable for IKEA Kallax: Technical Principles
As standard, the well-known cube shelving system has no continuous rows of holes on the inner sides of the compartments. The internal dimensions of a standard compartment are 335 mm in width, 335 mm in height, and 390 mm in depth. If additional levels are to be installed inside this carcase, mounting points for the shelf support fittings must be created manually.
Because the outer panels consist of a lightweight honeycomb structure, whilst the internal dividing walls often feature a more solid core of chipboard or MDF, selecting the correct fixing method is crucial. Standard wood screws gain no purchase in hollow spaces. For retrofitting shelves, standard System 32 is therefore relied upon to ensure standard-compliant and dependable support.
What to Consider for Compatibility: Dimensions and Hole Pattern
System 32 is the international standard in furniture construction. It defines the distance between drilled holes as well as their distance from the front edge of the furniture unit. Anyone looking for fittings as alternatives to IKEA systems must adhere to these metrics to ensure complete compatibility.
- Hole spacing: The vertical distance from hole centre to hole centre is exactly 32 mm.
- Front edge setback: The first row of holes standardly begins 37 mm behind the front carcase edge.
- Hole diameter: For internal shelves, a diameter of 5 mm is generally drilled. 3 mm is used less frequently.
- Drilling depth: With a material thickness of 15 mm to 18 mm, the hole is usually drilled 8 mm to 10 mm deep.
Drilling a row of holes afterwards without a guide square is akin to flying blind in the workshop – the shelves will inevitably wobble. Strict adherence to the measurements in millimetres is mandatory so that the load is distributed evenly across all four support points.
This grid remains consistent regardless of the carcase depth. Whether a cabinet carcase has a depth of 20 cm, 35 cm, 40 cm, or 50 cm, the principle of the front and rear row of holes does not change. For very deep cabinets (from 500 mm depth upwards), a third, central row of holes can be useful to stabilise shelves prone to sagging.
Suitable furnica Hardware for Shelving Extensions
For the secure placement of new shelves within an existing carcase, various fitting types are available that are suitable for IKEA furniture and other common modular grid systems.
The foundation is formed by classic shelf supports. These cylindrical or spoon-shaped pins made of steel or die-cast zinc are inserted into the 5 mm drill holes. For glass shelves or heavily used wooden shelves, variants with rubberisation or a plastic coating are recommended to prevent slipping and protect the surface finish.
If the shelves need to be firmly connected to the carcase to increase the rigidity of the unit, specialised shelf supports & brackets with cam-lock or screw connections are utilised. In this case, a pin engages into the support, which is subsequently locked from underneath. This prevents accidental lifting of the shelf.
For open-frame structures or whenever shelves are to be fixed to the wall outside of the carcase, a metal shelf bracket is the technically correct choice. These heavy-duty brackets absorb high forces measured in Newtons and transfer them securely into the masonry. Inside the furniture itself, compact shelf brackets are used instead, fitting flush into the system drilling.
If you extend the system not only with shelves but also with pull-outs, pay attention to the runner types. A full-extension runner allows complete access to the depth of the compartment, whilst a single-extension runner remains partially inside the carcase at the rear.
Installation and Retrofitting: Step-by-Step Guide
Fitting additional levels requires precision. Only use tools designed for machining melamine-coated board materials.
Required tools:
- Cordless drill driver
- 5 mm wood drill bit with centring point (brad point)
- Depth stop collar for the drill bit
- Drill template (for System 32)
- Folding rule and pencil
Step 1: Determine positioning Measure the desired height for the new shelf. Mark the position on the side panels. Ensure that the clear internal height between the shelves is sufficient for the intended items.
Step 2: Position the drill template Place the drill template flush against the front edge. An accurate template ensures that the 37 mm distance from the edge is maintained precisely. This is not only important for shelf supports, but also essential if doors are to be fitted at a later stage. The same jig often also assists with setting mounting plates for a 110° concealed hinge, compatible with IKEA Utrusta systems.
Step 3: Drill with a depth stop Equip the 5 mm drill bit with a depth stop set to a maximum of 10 mm. The centring point of the drill prevents slipping on the smooth melamine surface. Drill the four holes per shelf at an exact 90° angle into the carcase panel.
Step 4: Insert supports and place the shelf Push the shelf supports into the drilled holes by hand. They should fit tightly without splitting the edges of the hole. Afterwards, position the precisely cut shelf (recommended dimension for the standard compartment: 335 mm x 380 mm).
FAQ – Frequently Asked Questions Regarding Compatibility
Which drill bit is required for standard shelf supports? A diameter of 5 mm has established itself across the furniture industry. You must use a wood drill bit with a centring point to prevent breakout of the surface coating. Metal drill bits (HSS) are unsuitable for this purpose.
Can hinges be fitted inside retrofitted compartments? Yes. If you wish to close the compartment with a door, you require a concealed hinge with a 35 mm cup diameter. For overlay doors, choose full overlay mounting; for inset doors, select inset mounting. The cruciform mounting plate is fixed according to System 32.
How do I proceed with very narrow or shallow furniture? Hardware technology scales independently of furniture dimensions. For instance, when adapting a shoe rack 70 cm wide or narrow hallway sideboards with shallow depth (e.g. 25 cm or 35 cm), the distance of the drill holes from the front edge remains 37 mm. Only the rear row of holes moves closer to the front according to the carcase depth.
Are there alternatives to drilling? With hollow-core panels (such as the thick outer walls of some cube units), drilling is problematic because the plug or support cannot get a grip. Here, clamp supports or continuous vertical divider inserts can be used. For solid walls or constructions outside the carcase, such as wall shelves, traditional wall plug and screw fixings are used.
Matching Replacement Parts for Your Project
The exact matching of replacement hardware to the existing piece of furniture secures its durability. When looking for fittings to replace IKEA or other brands, always compare technical parameters such as cup diameter, hole spacing, and material thickness. Mechanical compatibility is the sole criterion for successful, long-term, stable installation.