Transforming Cube Shelving: Installing Furniture Legs & Adding Soft-Close Dampers

Transforming a standard shelving unit involves installing threaded furniture legs for added height and retrofitting soft-close dampers to the hinges and runners of modular inserts.

Cube shelving systems, such as the familiar IKEA Kallax, are generally manufactured from melamine-faced board materials. Whilst the internal partition walls are usually made of solid chipboard, the thick outer panels frequently consist of an MDF frame construction with a honeycomb paper core. This lightweight construction requires a solid technical understanding of the right fittings and fixings when carrying out modifications—such as attaching legs or fitting doors and drawers.

Upgrading such a shelving unit is like tuning an instrument: every screw and hinge must sit in exactly the right place so that the moving parts operate smoothly in daily use. This guide explains the technical fundamentals, how to select matching furniture hardware, and how to carry out a professional installation.

Types of Hardware for Shelving Transformations

To enhance the functionality of a shelving unit, various categories of furniture hardware are used. These can be divided into load-bearing elements for the carcass and moving mechanisms for the insert modules.

Furniture Legs and Base Constructions

Fitting legs raises the shelf off the floor, protects the bottom edge from moisture, and alters the visual presence of the furniture piece in the room.

• Threaded legs: These models feature a threaded bolt (typically M8 or M10) that is screwed into a threaded insert (screw-in bush) previously fitted into the carcass base.
• Screw-on legs: These legs have an integrated mounting plate with four screw holes and are fastened directly to the bottom panel using chipboard screws.
• Height-adjustable legs: To compensate for uneven flooring, the base of the leg can be rotated on a thread. A typical adjustment range is between 10 mm and 15 mm.

Suitable components can be found in our Furniture Legs category.

Hinges for Door Inserts

When the shelving unit is fitted with doors, concealed hinges are used. The classic cup hinge requires a circular recess in the door (the cup hole), which standardly has a diameter of 35 mm. For shelving inserts where the door sits flush within the compartment frame, an inset hinge is required. If the door overlays the side panels of the insert, a full overlay hinge is used. The typical opening angle for such compact compartments is 95° or 110°. Matching fittings can be found under Cup Hinges / Cabinet Hinges 110 Degrees.

Drawer Runners for Compartment Inserts

Drawers in standard inserts often slide on simple wooden battens or basic plastic runners. Upgrading to metal runners improves running smoothness and load capacity.

• A single extension runner allows the drawer to be pulled out to approximately 75% of its length. The rear section of the drawer remains inside the carcass.
• A full extension runner enables 100% extraction, providing complete access to the entire contents. Ball-bearing telescopic runners are most commonly used for this purpose. Further details can be found in the overview for Full Extension Drawer Runners.

Soft-Close Damping Systems

Damping prevents doors and drawers from slamming shut loudly. A hydraulic or pneumatic cylinder slows the movement down over the final few centimetres and pulls the element shut smoothly and quietly.

• For hinges, the damper is either integrated directly into the hinge arm or clipped on as a separate accessory. See Cup Hinges / Cabinet Hinges with Damping (Soft Close).
• For drawers, the mechanism is built directly into the runner. Corresponding models can be found under Soft-Close Drawer Runners.
• Alternatively, existing un-damped hinges can be retrofitted with a standalone door damper that is either drilled into or surface-mounted onto the carcass. A selection is available under Door Dampers.

How to Choose the Right Fittings (Selection Criteria)

Choosing the correct hardware depends on the unit dimensions, the weight of the inserts, and the properties of the board material.

1. Material Composition and Screw Selection

The outer panels of cube shelving units are often hollow (honeycomb core). Standard screws will not hold in the hollow void. However, the solid edge perimeter (usually made of MDF) is approximately 20 mm to 30 mm deep.

• When mounting furniture legs at the corners, use chipboard screws with a diameter of 4 mm and a length of 16 mm to 20 mm.
• Pay attention to the drive type: TX (Torx) offers the best torque transfer without slipping, whilst PZ (Pozidriv) is the standard in furniture fittings.

2. Dimensions for Drawer Runners

The depth of a Kallax shelf is 39 cm. Modular inserts are accordingly shallower. Measure the exact depth of the drawer box. Drawer runners are available in fixed length increments. For shelving inserts, you will usually require lengths in the range of 250 mm - 350 mm. The runner must never be longer than the depth of the drawer box.

3. Checking the Hinge Application Type

Examine how the door is positioned against the insert carcass.

• Door sits flush inside the side walls of the insert: inset mounting.
• Door covers the front edges of the insert side walls completely: full overlay.

Using the wrong hinge type will prevent the door from closing properly or cause it to jam. A complete overview of various opening angles and mountings is available in the Cup Hinges / Cabinet Hinges category.

4. Lift-Up Flaps Instead of Doors

If a compartment is designed to open upwards or downwards rather than sideways, it is classed as a flap. Cup hinges alone are insufficient here, as the flap would drop or slam shut uncontrolled. A gas strut is required. The force of these stays is measured in Newtons (N). For small, lightweight shelving flaps made of chipboard (approx. 33 cm x 33 cm), 50 N to 60 N is usually completely sufficient. Excessively strong struts (e.g. 120 N) will cause the flap to spring open violently and make it difficult to close. Matching options are available in our Gas Struts section.

Applications and Room Solutions

Modifying standard cube shelving significantly broadens its versatility across different living spaces.

In the hallway as a bench or shoe rack: Placing the unit horizontally allows it to serve as a hallway bench. Load capacity is crucial here. The furniture legs must withstand the weight of seated individuals. Choose solid metal or hardwood legs and install at least six legs (four at the corners, two centrally beneath the partition wall) to prevent the bottom panel from sagging.

In the living room as a sideboard: Adding slender metal legs (such as hairpin legs) and fitting doors with soft-close hinges turns a simple cube unit into a sleek sideboard. The damping delivers a high-end tactile feel typically associated with bespoke furniture.

In the home office for heavy files: When shelving inserts are used for heavy office supplies, replace basic plastic drawer slides with ball-bearing telescopic runners. A full extension runner makes it easy to retrieve documents stored at the very back of the drawer.

Installation Guide: Hardware & Step-by-Step Fitting

Accurate fitting requires precision. Always work on a level surface and use the correct tools.

Required Tools

• Cordless drill/driver with adjustable torque clutch
• Driver bits matching your screws (PZ size 2 or TX size 20)
• Wood drill bit (Ø 3 mm for pilot holes)
• Tape measure or folding rule and pencil
• If needed, a 35 mm Forstner bit (if drilling new hinge cup holes)

Step 1: Fitting the Furniture Legs

1. Positioning: Turn the shelving unit upside down. Mark the positions of the legs. Place the legs precisely in the corners, as this is where the solid material (the MDF perimeter frame) is located. Screws will not hold in the hollow centre of the panel.
2. Pre-drilling: Drill pilot holes at your marks using a 3 mm wood bit to a maximum depth of 10 mm. This prevents the melamine coating from splitting.
3. Securing: Position the mounting plate of the leg and drive in the chipboard screws (e.g. 4 x 16 mm). Use a low torque setting on your cordless driver to avoid stripping the screw threads in the board.

Step 2: Installing Soft-Close Hinges

When upgrading existing inserts, you can often swap out the old hinges directly.

1. Dismantling: Loosen the fixing screws on the old cruciform mounting plate on the inside carcass wall, and remove the old hinge from the door.
2. Inserting the new cup hinge: Press the 35 mm cup of the new soft-close hinge into the recess in the door. Ensure the hinge arm sits at an exact 90° angle to the door edge, then screw it into place.
3. Securing the mounting plate: Screw the new mounting plate to the inside wall of the insert. With clip-on systems, simply snap the hinge arm onto the mounting plate until it audibly clicks into place.
4. Adjustment: Use the three adjustment screws on the hinge arm to align the door in height, depth, and lateral reveal until the gap profile is neat and uniform.

Step 3: Retrofitting Drawer Runners

1. Measuring: Determine the internal width of the insert and the external width of the drawer box. A standard ball-bearing slide requires exactly 12.7 mm of side clearance on each side.
2. Fitting the carcass runner: Fasten the outer cabinet profile of the runner horizontally to the inside wall of the insert. Use the System 32 hole pattern if the spacing aligns, or mark and drill accurately.
3. Fitting the drawer runner: Screw the narrow drawer profile to the outer side of the drawer box.
4. Insertion: Slide the drawer box into the carcass until the runners engage. Test the soft-close mechanism.

For further damping options, including stick-on or drill-in buffers, explore our Buffers & Dampers section.

Frequently Asked Questions (FAQ)

Can I attach furniture legs to any cube shelving unit? In principle, yes, but screw positioning is critical. Because units like Kallax shelving often feature lightweight panels with a honeycomb core, the fixing screws for the legs must be placed strictly within the solid outer edge zone (the outer 20 mm to 30 mm). Screws will find no purchase in the hollow core.

What is the difference between soft-close and push-to-open? These two mechanisms serve opposite functions and must not be confused. Soft-close is a damping system that gently decelerates a closing door or drawer and pulls it silently shut. Push-to-open (or tip-on) is an opening mechanism for handleless frontals; pressing the door causes a spring-loaded pin to push it open. A soft-close hinge will not work in tandem with a push-to-open latch.

Which hinge do I need for a standard shelving insert? On most cube shelving door inserts, the door sits flush between the internal side panels of the insert. This setup requires an inset hinge. A full overlay hinge would cause the door to bind against the carcass frame.

How long should the drawer runners be for a shelving insert? Runner length depends on the depth of the insert's drawer box. With a typical shelving depth of 39 cm, the drawer boxes are usually around 33 cm to 35 cm deep. The runner must be shorter than or equal to the length of the drawer box. Common lengths used for this purpose are 300 mm or 350 mm.

Can I convert a shelving door into an upward-opening flap? Yes. In addition to hinges (ideally unsprung flap hinges), you will need a gas strut. This supports the flap in the open position and cushions its descent when closing. Strut strength is specified in Newtons. For small shelving inserts, 50 N is usually sufficient.

What should I do if a screw hole in chipboard is stripped? If a screw spins freely because the core material has stripped, drill out the hole cleanly with a wood drill bit (e.g. 6 mm or 8 mm), insert a matching wooden dowel with wood glue, and trim it flush once dry. You can then drive your screw into the exact same position.

Related Categories & Hardware Guides

To complete your transformation project and source the appropriate fittings for your shelving upgrades, explore our dedicated hardware categories:

• For silent door closure: Cup Hinges / Cabinet Hinges with Damping (Soft Close)
• For full access to drawer contents: Full Extension Drawer Runners
• For smooth-gliding drawers: Soft-Close Drawer Runners
• For retrofitting dampers onto existing doors: Door Dampers
• For elevating and supporting the carcass: Furniture Legs
• For constructing lift-up flaps instead of standard doors: Gas Struts
• For inserting additional internal shelves: Shelf Supports & Brackets