ᐅ My KALLAX was installed on a screed floor – potential moisture issues?

Created on: 3 Jan 2023 08:37
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Nonplo
Hello everyone,

I recently installed an IKEA KALLAX shelving unit directly on a screed floor. Unfortunately, I am now concerned that this might cause moisture problems. Although the screed has fully cured, the room is an unheated basement that occasionally gets somewhat damp—even though there are no visible water puddles.

My specific question is: Can placing a KALLAX shelving unit directly on the screed floor cause damage due to rising or standing moisture? Are there any recommendations on how to best protect or position the shelving unit to prevent issues such as swelling, mold, or mildew?

I would greatly appreciate any experiences or advice, especially from anyone who has dealt with something similar or is familiar with such situations. Thanks in advance!
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Santi
3 Jan 2023 11:24
You should definitely place a plastic sheet as a barrier between the screed and the shelving. Additionally, regular ventilation helps prevent moisture problems.
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blapau
3 Jan 2023 12:03
As an additional tip, I would recommend checking the moisture content of the screed before installation using an appropriate measuring device. The screed should be completely dry – ideal values are below 2 CM % (calcium carbide method) or a maximum relative humidity of 65% in the room.

If this is ensured, a simple polyethylene (PE) sheet is often sufficient as a separation layer to protect the furniture from moisture. Be sure that the sheet is not too small to prevent moisture absorption from the sides.

I would also advise against placing a tightly fitting carpet directly under the shelf. It is better to allow some air circulation.
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sinhau
3 Jan 2023 12:47
Hello Nonplo,

I would like to add some notes about moisture in screed floors and how to position the shelving correctly:

1. Cause: Screed floors, especially in basements, release residual moisture that can escape over weeks or months. Even if the screed appears dry, moisture can be absorbed into wooden materials placed on the floor.

2. Stages: There is a distinction between 'dried' and 'not completely dried' screed. The former is generally not a concern, while the latter requires special protective measures.

3. Protective measures:
- Place a plastic sheet (at least 0.2 mm thick) between the shelving and the floor
- Use feet or supports under the shelving to create a gap from the floor
- Improve indoor climate by airing the room (use ventilation by opening windows briefly, avoid continuous ventilation)

4. Common mistakes:
- Placing furniture directly on a moisture-retaining floor without protection
- Using moisture-sensitive materials without any protective layer

Summary: Ideally, start with a moisture measurement, then use a protective sheet plus spacers. If the shelving is already in place, spacers and ensuring air circulation can help mitigate the issue.

If you like, I can also provide a brief guide on how to perform the moisture measurement yourself.
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Nonplo
3 Jan 2023 14:16
Laukau5 schrieb:
I recommend the following approach:

Thank you, Laukau5, that exactly matches my thoughts! So far, I haven’t done any moisture measurements, but I’m planning to order one to get accurate values.

At the moment, the shelf is placed directly on the screed floor, which I will probably have to change. I have a PE sheet here, and I will make an underlay.
sinhau schrieb:
If the shelf is already in place, you can counteract by using spacers and allowing air circulation.

That sounds doable. Is it still easy to fix later on, or is there already a risk of initial damage?

And how often should a cellar room like this be ventilated? It’s dry, but kept at a temperature between 10-13°C (50-55°F).
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koduga
3 Jan 2023 15:27
Nonplo schrieb:
Is it still possible to easily fix this later, or is there already a risk of initial damage?

I asked the same when I noticed my shelf was already slightly swollen. You can still save a lot if you act quickly. I removed the shelf, thoroughly dried everything, and installed spacers. After that, there were no further problems.

Regarding your ventilation schedule: I always ventilated thoroughly in the morning and evening, with 10 minutes of full window ventilation each time. This completely replaces the humid air. Continuous ventilation in cold weather is not very effective.

So: act quickly before it’s too late!
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Elias
3 Jan 2023 17:42
Nonplo schrieb:
How often should you ventilate a basement room like this?

I would say at least twice a day, with a quick full ventilation for 5-10 minutes, especially if the humidity is above 60%. This helps prevent moisture buildup.

You can easily monitor this using a hygrometer and adjust accordingly.

Thumbs up for taking the right approach by measuring from the start! 🙂