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Hattix t1_je5um9m wrote

That's efflorescence. It means you have a moisture problem, not a mold one.

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Moogy_C OP t1_je5vb03 wrote

Ah, thank you, I'll start looking into it. Theoretically, better ventilation should prevent this from appearing then? There are no water sources other than rainy weather.

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Sluisifer t1_je60tsv wrote

What you see is salt. Water is in the concrete and there is salt dissolved in the water. When the water evaporates on the surface of the concrete, salt crystals remain.

More ventilation just means that the drying happens faster, but does not change the amount of water and salt that is in the concrete. So no, ventilation does not help. You need to prevent moisture from getting into the concrete in the first place. This may mean fixing leaks, grading around the foundation, sealing, etc.

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Moogy_C OP t1_je61p14 wrote

Great answer, thank you very much.

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georgenhofer t1_je5wpbg wrote

There is moisture underneath where that spot is showing.

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Moogy_C OP t1_je5x52t wrote

So you're saying ventilation would not help if that's the case? We haven't had a problem here in almost 10 years living here.

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georgenhofer t1_je5xl5c wrote

Ventilation would help, but there likely has been a lot of rain recently then, and runoff is going under your concrete pad. Likely the reason for the crack too, when freezing underneath.

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