Damp basement from inside or outside?

Hello,

we have a house from 1971. The heating room can be seen in the picture. On the right is the chimney shaft - this was damp until January - leaking roof.

As a result, in the rooms above, the wallpaper in the area of the shaft was slightly damp in places.

In the basement, there was water standing about 0.5 cm a few times (the traces can be seen in the picture).

I never thought about the plaster peeling off on the exterior wall. I bought a moisture meter and measure 10-18% wall moisture at those spots. In the area of the chimney shaft on the floor, occasionally 20 percent or more.

Can I assume that the moisture comes from the chimney shaft and will dry out over the next months/years by sealing the leak on the roof?

Or could it theoretically be that, given the damage pattern, the moisture comes from outside and I have a bigger problem?

How should I proceed? Should I wait at first? What could happen in the worst case?

In the other basement rooms, the wall moisture is 5-10 percent, humidity just under 6 percent.

Thanks!!

As you can see from the efflorescences, this is a general problem. In my opinion, the sealing of the basement walls is inadequate. Have a specialist check it. A forum cannot do that. An on-site appointment belongs there.

Moisture in the basement is normal. More likely not yet a problem. But if mold forms, action should be taken immediately.

As you can see from the efflorescences, this is a general problem. In my opinion, the sealing of the basement walls is inadequate. Have an expert check it. A forum cannot do that. An on-site appointment is necessary. Moisture in the basement is normal. Rather not yet a problem. But if mold forms, you should take action immediately.

Do you mean the efflorescences on the floor? That came from the shaft and was fixed (roof renovation). The floor is completely dry now.

humidity just under 6 percent.

You hopefully mean under 60%?

You mean hopefully under 60%?

Yes, 60 sorry I mistyped. Is a damp basement wall without mold a problem or can you leave it?

Do you mean the efflorescence on the floor? That came from the shaft and was fixed (roof renovation)
The floor is completely dry now.

No, I mean the ones on the walls. Everywhere the paint is peeling off.