Retrofitting Drawers for IKEA Pax

Retrofitting drawers into modular wardrobe systems requires precisely matched drawer runners that are compatible with the standardised hole pattern of the carcass.

Anyone wishing to expand an existing wardrobe with additional storage space often faces the question of finding the right components. Especially with widespread models, joiners and fitters frequently look for reliable components that are compatible with IKEA Pax. Whether it is about replacing defective runners or building entirely new solid timber drawers for the carcass – choosing the right fittings determines the durability and load capacity of the construction. In this article, we examine the technical requirements, dimensions, and suitable system components that serve as an alternative to factory-fitted runners.

Compatibility: What to look out for regarding dimensions and hole series

To integrate drawer runners precisely into a carcass, the internal dimensions and existing drill holes must be analysed accurately. Most modern furniture carcasses, including those from Swedish furniture retailers, are based on System 32. This means that the rows of holes in the side panels have a vertical spacing of exactly 32 mm from one another. The diameter of these pre-drilled holes is typically 5 mm, which enables the use of standardised Euro screws.

The second decisive criterion is the internal installation depth (clear depth) of the wardrobe. The Pax carcass is primarily available in two depths:

• Depth 58 cm: The clear internal depth here is around 560 mm. For custom-built drawers or retrofitting, runners with a nominal length of 500 mm to 550 mm are used here.
• Depth 35 cm: With the shallow variant, the internal depth is just under 330 mm. Here, drawer runners 300 mm are the technically correct choice to prevent a collision with the back panel.

Suitable drawer runners for wardrobe conversions

If you make your own drawer boxes out of timber or coated chipboard, you only require the fittings. The range of drawer runners offers various mechanical approaches for this, tailored to the desired convenience and load rating.

Extension type: full extension vs. partial extension

Due to its design, a single extension can only be pulled out of the carcass to roughly 75%. The rear part of the drawer remains inside the wardrobe, which makes accessing clothing items stored at the back of deep wardrobes difficult. A full extension, on the other hand, releases the entire drawer box (100% extension travel). For deep wardrobes, full extension drawer runners are the technical standard to guarantee ergonomic use.

Runner type and mechanics

The side-mounted ball bearing runner is robust, low-maintenance, and adapts flexibly to different drawer widths. Alternatively, undermount runners can be used, where the mechanism is mounted invisibly beneath the drawer base. However, this requires precise routing and calculation of the base thickness.

Regarding comfort features, a distinction must be made between two opposing mechanisms:

1. Damping: Drawer runners with soft-close absorb the momentum during closing and pull the drawer shut gently and silently over the final centimetres. This requires the drawer to have a handle.
2. Tip-On: Push to open drawer runners are designed for handleless fronts. Light pressure on the front triggers a mechanical spring that pushes the drawer out slightly.

Load capacity for wide carcasses

With a carcass width of 100 cm, the combined weight of the drawer and heavy items of clothing such as jumpers or jeans creates significant leverage. Standard runners with a 25 kg load capacity quickly reach their limits here. For elements this wide, heavy duty drawer runners with a nominal load capacity of 35 kg to 45 kg should be planned in order to prevent flexing or jamming of the ball bearing runner in the long run.

Complete systems and internal fittings

Those who do not want to glue or screw together their own wooden boxes can turn to complete drawer systems. These consist of double-walled metal drawer sides (the side panels of the drawer), the matching drawer runners, and brackets for the front and back panels. The fitter only needs to cut the base and back panel from 16 mm thick material (usually melamine-faced chipboard). Such systems serve as an excellent, sturdy alternative to standard IKEA components.

Following the successful installation of the basic components, drawer accessories provide the finishing touches. A non-slip drawer mat prevents ties, belts, or folded garments from sliding around when opening and closing. If the wardrobe is used in commercial environments or shared flats, a drawer lock can also be retrofitted to secure private documents or valuables against unauthorised access. The cylinder lock is drilled directly through the drawer front using a Forstner bit.

Installation and fitting: step-by-step

Fitting runners is like laying railway tracks – only when both sides are screwed in completely parallel, level, and at the exact same setback from the front edge will the drawer glide smoothly later on.

Tools required

• Cordless screwdriver with driver bits (PZ or TX drive)
• Tape measure and folding rule
• Small spirit level
• Bradawl or awl
• Euro screws (for 5 mm drill holes) or chipboard screws (e.g. 4 x 16 mm)

Installation procedure

1. Define height: Determine the position of the drawer inside the carcass. Use the existing 5 mm holes of the 32 mm hole series.
2. Separate the runners: With a ball bearing runner, the inner profile (which attaches to the drawer) must be unlatched via the small plastic release lever and pulled out of the carcass rail.
3. Fit the carcass rail: Place the rail against the row of holes. Ensure the correct setback from the front edge (usually 2 mm to 5 mm, depending on front thickness). Secure the rail with Euro screws.
4. Fit the drawer profile: Screw the unlatched inner profile flush to the lower side edge of the wooden drawer.
5. Marriage: Insert the drawer with the fitted profiles horizontally into the carcass rails and push it backwards with light pressure until the mechanism audibly clicks into place.

Frequently asked questions (FAQ) about retrofitting drawers

What runner length do I need as an alternative to IKEA Pax runners? For the deep carcass (58 cm external dimension), you require runners with a length of 500 mm. For the shallow carcass (35 cm external dimension), choose runners with a length of 300 mm. The clear internal depth of the wardrobe must always be at least 3 mm to 5 mm greater than the nominal length of the runner.

Can I combine soft-close and push-to-open? No, these are two mutually exclusive mechanical systems. A soft-close mechanism actively pulls the drawer shut and holds it closed. A tip-on mechanism actively pushes the drawer open. Combining them in the same runner is technically not possible.

How do I fix the runners if the hole pattern does not match? If the pre-drilled holes in the System 32 grid are not sufficient for the desired height or are obstructed, you can screw the runners directly into the carcass side panel using standard wood screws (countersunk, 4 x 16 mm). Use a spirit level and pre-punch the holes with an awl so the thread catches immediately and the wood does not split.

What clearance gap do I need to calculate when building my own timber drawers? This depends on the chosen runner. A standard side-mounted ball bearing runner typically requires exactly 12.7 mm (often rounded to 13 mm) of space on each side. The external width of your wooden drawer must therefore be exactly 26 mm narrower than the internal clear width of the wardrobe carcass.