Wet spots in new construction!

Hello my dears, the screed has been in the house for 10 weeks. The walls and screed still have a lot of moisture that is coming out. We have had the heating on for about 3 weeks now. Even before the heating was on, we saw these spots. Now they have appeared again in exactly the same places. What do you think about it? Condensation spots or moisture penetrating from outside?

Hi,

only someone who really knows a lot about this can tell you exactly.

To me, the spots in the photos don’t look like condensation stains. Because the spots look as if there is a lot of moisture in them (do you have access to a moisture meter?).

As the building expert said recently quite rightly: water finds its way, it doesn’t have to run into the house where it comes out inside.

If it were due to condensation, it would suggest that there are significant thermal bridges at the shown spots. Also not particularly good. Were the stains just as noticeable before the heating was turned on?

In my opinion, you definitely need to have the exact situation and background examined with the help of a suitable expert. I would certainly not just leave it alone. If something is really wrong, you will get trouble and costs later from consequential damage......now everything is still easier to manage.

Besides possible damage to the building envelope (water ingress from outside), damage to a water pipe or heating pipework is also possible. The latter happened to a colleague of mine two years ago. Not noticed in time (nothing done), then the awakening came: screed had to be completely removed (move out of the house again!). Such actions in "" can be prevented.

Best regards
Thorsten

PS: After 10 weeks, screed usually has already completed a large part of its curing. Of course, moisture still escapes, but in the first 2-4 weeks this is significantly more than today after 10 weeks. But: last week we had very heavy rain almost everywhere in Germany.....and storms.

what kind of plaster do you have on the wall??? Lime-gypsum???
it’s similar with us....plaster was done at the end of October, and screed at the beginning of November, for 10 days we have been gently heating up, and the walls are still not properly dry, after now 6 weeks!
the damp spots are more widespread with us, but not as thoroughly soaked as with you. But also mostly in the corners.
we were told that the plaster might not have been stored completely dry and was applied with a certain moisture... but that can’t be because the plaster would already set, it should actually clump!?
does anyone here know why the drying takes so long?

Does anyone here know why the drying takes so long?

When curing plaster, screed, and the like, moisture is released in considerable amounts over weeks.

By remote diagnosis (and without knowing the exact moisture level of the wall through measurement, measuring wall temperatures, measuring humidity, etc.), it will be difficult to impossible to assess the situation on a case-by-case basis.

If this had happened to me during construction, I would have simply hired an expert for 200,- and had them take a look. These people are trained for this, and the few euros are well invested. If everything is fine, you have peace of mind. If something is wrong, you can get to the bottom of it and fix the issue.

In order to clarify the damage progression, the structural frame must be known. Is it a timber frame/timber panel construction? Or a solid construction? Large amounts of mixing water are brought into the house through plaster and screed, which must either be removed by sufficient ventilation or collected by dehumidifiers. The damp spots suggest massive condensation from uncontrolled convection of warm, moist air on cold components (thermal bridges). For example, through the roller shutter strap drive into the roller shutter box. Or through a variable moisture vapor barrier into the insulation between the rafters and from there as liquid water down to the foot purlin, where, for example, the ceiling could become dampened. Such areas must be opened if possible. Have you had a blower door test performed, during which leak detection was also possibly carried out?

You can also measure the relative humidity and, if necessary, set up dehumidifiers, whereby after 10 weeks the greatest moisture ingress should have long since passed. It is possible that moisture has condensed more heavily in certain areas from which it can no longer evaporate and is now seeking new capillary paths. Mineral insulation in the roof area (mineral wool or glass wool) can become very damp in this way but dries poorly after installation because it does not allow capillary moisture transport.

Basically, the construction moisture will eventually be completely dried out if the component structure and moisture supply from residential use allow it.

Possibly the moisture has condensed in liquid form more massively at certain spots, from which it can no longer evaporate and is now finding new paths capillary-wise. Basically, the construction moisture will eventually be completely dried out if the component structure and the moisture supply from residential use permit it.

Hello W. Pickartz,

the words of the expert (architect) - I had already thought and hoped that you would join in the thread.

In this case, you have partially confirmed/clearly specified my layman's understanding in some points.

What makes me suspicious about the pictures is exactly the image where the moisture is visible seeping out between ceiling and wall. It looks "drip-wet" there (it is just a photo after all... what one can see there). That is not just a little water... the spot is - from the gut feeling - totally strange. The spots on the roller shutter boxes indicate thermal bridges to me (condensation). Whether the water comes from the screed entry or from somewhere else (well stored and now pressing out via capillary action): It is certainly harder to assess (or only on site/by some measurements)? The spots were gone according to the original poster's interpretation. And now they are "suddenly (more) back." And last week there was heavy rain... also in Bavaria.

I will continue to observe the thread. I am curious how the original poster fares and what happens next there. I hope for the original poster that it is construction moisture and nothing else!!!

Once again something from the layman: If I were the client there, I would not like the almost 100% thermal bridges present at the roller shutter box at all!

Best regards Thorsten