Moisture problem in interior walls

Hello everyone,

as already mentioned in other threads, our project involves converting an old barn into residential use (we are currently removing the old floor and chipping off the plaster from the walls). We now have the following problem:
A completely new inner shell including insulation will be installed in front of the (old) walls that are currently standing. The (old) walls that are already standing are partially very damp; in some places you can already see the moisture that has penetrated (where we removed the old plaster). The question now is to what extent this poses a problem for the new inner shell and insulation? Part of the floor is also damp because the building (the windows) are not all sealed. Is this also a problem for the new concrete slab? We are very cautious regarding moisture and are deeply concerned that it might cause problems later on.
Thanks in advance for your help!

Best regards
- wilsumer -

Barn and plaster - how does that fit together? - only on the outside, I suppose (?)

Even with what I would call "a building-covered plot of land," a soil survey can be useful. What is the soil structure like, and what is the construction year of the barn?

In the case of moisture remediation, experts in building damage with this specialization should always be consulted. I would also wait for a while with further construction after a professionally carried out building drying. Additionally, there are many very different types and causes of moisture damage. The "right" treatment for one can apparently work against another, but not sustainably. Simply removing damaged material and replastering does not help; specialists need to be involved.

What does "windows not all sealed" mean: are the individual damage points assigned to those caused by driving rain penetration (exterior wall, window reveals and sills), those caused by rising damp (foundation walls), and those caused by seepage rain penetration (roof)?

Plaster is only on the inside. No idea why, but that's how it is.

Floor construction: There were about 40 cm of concrete and stones and now we basically have sand everywhere. In between, there was at least partially a PE foil and insulation material. Year of construction approx. 1960-1970. Formerly a pigsty, but has been completely empty for about 15 years.

The windows are not sealed, meaning that sometimes only the frame is present and it practically rains directly inside. The doors are also partly damaged so water has an "easy game". Luckily the roof is completely sealed, but it will still be completely renewed.
So I would (as a layman) say that the wet walls are almost exclusively limited to the areas around the windows and doors. The floor is only damp in one spot, which is most likely also explained by a defective door.

The question that generally arises for me is whether this moisture actually doesn't matter, since we are getting a completely new inner shell and base slab, both of which will be quite well protected against moisture. I only worry a lot about the insulation material between the old and new wall!

Ah, you led me down the wrong path there, stable is not barn. Barns in my area are mostly made of unplastered pumice masonry. For stables, plaster on the inside makes sense, as does a concrete floor; barns more often have only compacted floors, possibly with a cemented top layer.

Regarding the windows, I suspect iron with single glazing in putty bedding (?)

Vacancy is the best accelerant of decay ;-(

Any moisture damage must be thoroughly remedied. You cannot ignore or seal it.

In the case of a double-shell exterior wall with the particularity of outer and inner shells of different ages and the outer shell having a history of moisture damage, I would only provide a generously sized air gap in between. High-density insulating materials are a foolish idea there for ambitious mold growers.

To put it bluntly: dry rot is cancer for buildings. When it comes to moisture damage, speculating to save money is the wrong approach; without a sound diagnosis, you easily end up with the wrong treatment. And the hope that simply not adding new moisture to the fabric is enough does not hold up.

Yes, of course, barn is not the same as stable. So it is/was a stable. My mistake.

The windows are, I think, made of concrete, but partly without glass. So rain can fall directly inside, and it has rained inside over a longer period. The gutters on the outside are also damaged in some places. You can also see the moisture on the masonry there. So we are quite sure about the causes.

I can’t currently say exactly how the architect and the construction company planned the insulation. Both are experienced in converting stables/barns. So they should know, but I will of course point it out again.

How can the moisture damage be repaired? Renovation plaster? Or do the "wet" areas even need to be generously renewed? That would, of course, be a major disaster. Although the areas are not huge, it would of course cost quite a bit.

Yes, of course, a barn is not the same as a stable. So it is/was a stable. My mistake

That was not just a matter of terminology, but a significant difference: a barn is used for dry storage, whereas a livestock stable houses creatures that feed and defecate moistly, which is why it is also built for wet cleaning.

How can the moisture damage be repaired? Renovation plaster? Or do the "wet" areas even have to be generously renewed?

You have to be very brave now: yes, that is exactly the difference between renovation and cosmetic treatment. Renovation always goes into the substance.