ᐅ Kallax Floor Warped – Cause: Excessive Weight?

Hello everyone,

I have the following issue with my Ikea Kallax shelving unit: The middle shelf, which holds several books and some decorative items, has noticeably bowed downward. The unit has been in use for about 2 years and has never been heavily loaded. Despite that, there is now a slight warping effect, which bothers me.

My question to you is: Can this shelf sagging really be caused by too much weight, or could other factors such as material fatigue, assembly errors, or environmental conditions also play a role?

I haven’t precisely measured the weight distribution on the shelf yet, but it is about 15-20 kg (33-44 lbs) spread over approximately 60 cm (24 inches) in width.

I look forward to your assessments, especially regarding the durability and safety of the shelving unit. Thanks in advance!

Mutar schrieb:
Can this floor deflection really be caused so much by excessive weight, or could other factors like material fatigue, installation errors, or environmental conditions also play a role?

That’s almost a rhetorical question. Of course, weight plays a major role! IKEA shelves aren’t designed for heavy loads, so eventually the floor simply can’t hold up anymore.

But honestly, who stacks books and decorations without considering the weight? An installation error can accelerate failure, but the main cause is probably continuous load stress.

And material fatigue in particleboard is no secret. Anyone expecting a simple shelf to hold 20 kg (44 lbs) on one plank for years without any issues is naive. The real question is whether it was really 20 kg (44 lbs) or maybe even more?

Yes, too much weight will deform the shelves.
Also, check whether all dowels and screws are properly fixed.
Particleboard has a limited load-bearing capacity; this is normal.

Hello Mutar,

I can understand your situation well. The Kallax shelves are made of coated particleboard with a specific load capacity provided by the manufacturer—usually around 13-15 kg (29-33 lbs) per shelf, depending on the load and support.

If the shelf surface is loaded over 60 cm (24 inches), the board may bend, especially if the weight is concentrated in one spot (for example, many books in the center of the shelf). It’s not only the weight that matters but also the duration of the load and how evenly it is distributed.

Besides the weight, the quality of assembly can be a factor. Is the shelf built exactly at a right angle and are all joints secure? Sometimes the connections lose stability over time, which makes bending easier. Moisture and temperature fluctuations also affect particleboard, causing the material to swell or weaken.

A possible solution is adding extra reinforcement to the underside of the shelf or redistributing the load across multiple levels. If the load is permanently this high, a heavier piece of furniture with solid wood shelves might be advisable.

I hope this helps you assess the situation!

theota schrieb:
Who stacks books and decorations without considering the weight?

Haha, you’re right, theota! 🙂

But honestly – who hasn’t experienced this? You place things in just by feel, and quality control with IKEA furniture isn’t always 100%.

I once had a Kallax shelf board that sagged slightly after a while, but I just rearranged and put lighter items on it. A bit of patience and care usually helps, and it holds up again for some time.

If your shelf looks like that, I would definitely try to redistribute the load, maybe put the heavier items at the bottom. And if that’s not enough, as angel mentioned, adding extra reinforcement helps 🙂

Winking: the shelves are just getting their “workout” – too much weight means sore muscles. 😉

Too much weight definitely causes bending.
If possible, reduce the load or redistribute it on the shelf.
Check the installation and alignment.