ᐅ Experience with Kallax as storage shelving under a staircase?

Hello everyone,

I am currently planning to reorganize the storage space under my staircase and am considering using the Kallax shelving system from IKEA as storage shelves there. Therefore, I am very interested in hearing about your experiences with Kallax installed under a staircase.

Specifically, I am curious about how stable the shelves are in this unusual space, whether they adapt well to the partially sloped surfaces, and what methods you have used to make the best use of the shelves’ height and depth. It would also be helpful to know about the load capacity, especially when storing heavy items.

Are there any issues with installation, particularly regarding wall mounting? And how does it work when combining multiple Kallax units?

I look forward to your answers and advice, including practical tips!

I have a Kallax shelf placed under my stairs and can say: it is sturdy if you anchor the units to the wall.

You need to cut the sloped wall or simply take it into account during planning.

Load-bearing capacity is good, but it’s better to store heavy items on the lower shelves.

Hello Bopau56,

I find your question very practical, as many stairwell areas often go unused. The best way to use the Kallax system is to start by measuring the dimensions very precisely, especially the height and any slopes.

As Santi already mentioned, the most important aspect is wall mounting – this provides extra stability. Without it, the individual modules can wobble or shift.

Additionally, I recommend securing the shelves at the connecting points, especially when using multiple modules, for example with screws or brackets from the inside, to reinforce the overall structure.

Regarding load capacity, Kallax usually holds up well for household use, as long as you are not storing very heavy machines or materials. It is advisable to place the heaviest items on the lower shelves – this follows simple physical principles and reduces the risk of tipping.

If you measure the lowest point of the stairwell opening accurately, you can also combine Kallax elements freely or even use cut pieces to maximize the available space.

Do you already have a rough idea of the stair height and the type of items you plan to store?

Ianlau schrieb:
I find your question very practical, as many stair areas remain unused.

I can only agree with that. From my experience, the biggest challenge with Kallax under the stairs is actually adjusting to the often sloped ceilings. The main advantage is the modularity of the shelves. You can easily combine individual modules and, with a bit of sawing, create a tailor-made solution.

I also strongly recommend not only securing the modules to the wall but also connecting them to each other with joining brackets. This prevents any movement or shifting.

Regarding load capacity: The Kallax units are made of medium-density fiberboard (MDF), which is sturdy but not ideal for very heavy loads – around over 15-20 kg (33-44 lbs) per compartment. You need to consider what you want to store. It works very well for boxes, books, or smaller equipment.

It would also be good to know if your stair area is protected from moisture, as MDF is sensitive to dampness.

Santi schrieb:
You need to cut the slanted wall or simply take it into account during planning.

Thanks for the tip. How difficult is that? Do you need to adjust the side walls of the modules accordingly, or is it enough to just trim the back panel?

Ianlau schrieb:
Do you already have a rough idea of the stair height and the type of items you want to store?

The height under the lower section of the stairs varies from about 100 cm to approximately 150 cm (39 inches to 59 inches). The depth of the area is roughly 40-45 cm (16 to 18 inches). The plan is mainly to store lighter items such as boxes with seasonal decorations, some tools, and a few books.

Moisture is not an issue in this area; the wall is a standard interior masonry wall.

I’m wondering if it might be possible to use a combination of a taller and a shallower Kallax module to better utilize the slant, or if that would be impractical.

Bopau56 schrieb:
I’m wondering if I could possibly work with a combination of a taller and a shallower Kallax module to better utilize the slope

That is a very sensible idea. I completed a similar project some time ago myself. It’s important to position the modules so they make the best use of the available height while still remaining accessible.

Simply trimming the back panel usually isn’t enough to adapt to a slope. The side panels should also be adjusted, as the Kallax back panel is not load-bearing but primarily provides stability. The main load is carried by the side panels.

If you remove material on the sides, make sure to sand thoroughly and possibly seal the edges, since MDF is sensitive to moisture and mechanical stress at cut surfaces.

A tip: when combining multiple modules, it’s best to use sturdy corner brackets to reinforce the structure. Also, make sure to secure the modules to the wall—this is essential, especially near a staircase where vibrations can occur.

Regarding load capacity: Kallax works well for everyday items, but I would avoid stacking heavy toolboxes to prevent sagging of the shelves.

If you plan to use the storage intensively later, you might consider replacing individual shelves with stronger boards. However, this requires some DIY skills.

What are your options for wall attachment? Do you have masonry walls or drywall?