ᐅ Experience: Kallax shelves bowing after several months – what can be done?

Hello everyone,

About 8 months ago, I bought a Kallax shelf and used the standard shelves. Recently, I noticed that the shelves have started to warp over time, with some bending upwards quite noticeably, which affects the weight they can support. I have tried to distribute the load evenly, and the shelf is placed in a location without direct sunlight or humidity, which I thought would rule out those factors.

Has anyone else experienced something similar and maybe found solutions to prevent this? Is it worth completely replacing the shelves with other materials? Or are there tricks to stabilize the shelves?

I’m looking forward to your tips and experiences, as I don’t really want to continue using the shelf like this :-)

Yannik schrieb:
Lately, I’ve noticed that the shelves have started to warp gradually, some bending upwards quite noticeably and affecting the weight they can hold.

Oh yes, I totally know what you mean! I had the same issue and was pretty disappointed at first since the shelf was supposed to be sturdy. 😊 But hey, this happens more often than you might think, especially with cheaper particleboard shelves.

What I did was have extra thick shelves cut from MDF at the hardware store. They’re a bit more expensive, but super strong and haven’t caused any problems since! It’s really great because the added stability makes a big difference and your shelf also looks neat and tidy.

Give it a try, it’s definitely worth it! 🙂 And don’t worry – you can easily upgrade your shelf without having to buy an entirely new one!

Yannik schrieb:
I tried to distribute the load evenly, and the shelf is placed in a location without direct sunlight or moisture

Thanks for the detailed information; it makes the analysis easier. Basically, IKEA shelves in the Kallax system tend to bend because of the relatively thin particleboard with a melamine coating. This material warps under constant load due to limited tensile and compressive strength.

A few important points you should check:
1. Load: How many kilograms per shelf are you placing? These shelves are designed for a maximum of 15 kg (33 lbs); beyond that, it gets critical.
2. Humidity: Even if the location seems dry, indoor humidity levels can vary significantly, causing wood-based materials to swell.
3. Additional reinforcement: Some users place metal brackets or narrow strips underneath the shelves to reduce sagging.

If you want to replace the shelves, I recommend MDF or plywood shelves with a thickness of at least 16 mm (0.63 inches), which significantly improves strength and durability.

One more thing that might be relevant: Are you using the shelves purely horizontal, or do you have additional drawers or boxes that might create point loads?

I’m happy to help if you provide more details!

Yannik schrieb:
Is it worth completely replacing the shelves with other materials? Or are there tricks to stabilize the shelves?

Replacing the insert shelves is generally advisable and recommended by many users if sagging occurs. The original Kallax shelves are made of 11 mm (0.4 inch) particleboard, which bends under load.

An effective measure to stabilize them is to replace the shelves with 15–18 mm (0.6–0.7 inch) thick MDF or plywood boards. The increased thickness and the uniform structure of MDF provide significantly better load-bearing capacity and prevent sagging over time.

Alternatively, reinforcement strips made of metal or wood can be mounted underneath the shelves to temporarily increase bending resistance, but this is not the best long-term solution.

In general, I recommend not exceeding the maximum load per compartment; IKEA specifies about 13–15 kg (29–33 lbs). For heavy items, using more durable materials should definitely be considered.

Kolepau schrieb:
I had extra-strong MDF shelves cut to size at the hardware store. They are a bit more expensive but extremely sturdy.

I really appreciate when people share genuine experiences here. It truly sounds like replacing the shelves is a very practical solution. However, I understand that this might not be so straightforward for everyone – sometimes time, the right tools, or even knowledge about which boards are actually suitable can be lacking.

@Yannik: How are you generally managing with assembling the shelf? Have you ever taken it apart or reinforced it? Sometimes we tend to just leave things as they are because we want to keep effort and costs minimal. If you like, I can share my experience with disassembling and modifying mine, maybe it will help you decide. 🙂