Hello everyone,
my neighbor (terraced house) had a major water damage incident, and apparently the water came over the shared concrete slab into our property (the basements are separated by two hollow brick walls, waterproof concrete only on the outside). There was about 2 cm (1 inch) of standing water in our basement for approximately 3 hours.
The drying company started working immediately, but in two of our basement rooms, there is no insulation layer under the screed; it seems the screed is laid directly on the concrete slab, and there is no plastic membrane in between. Interestingly, at the edges, there is the typical plastic perimeter insulation strip usually found with floating screed. Does anyone understand why it was built this way?
Current situation:
Room 1: 8 cm (3 inches) of bare screed (no floor covering). After 3 weeks of drying with condensation dryers, the floor appears to be in good condition again. However, the edges are still more damp than the center, probably because the water was able to penetrate the concrete slab via the perimeter insulation strips. The bottom row of bricks (above which there is a horizontal damp-proof course) is also normalizing in moisture content (35 digits vs. 18 digits in the drier bricks higher up).
How do you assess the chances that it’s just a matter of time before the screed fully dries out? How long might this take? The water was in contact with the entire surface from above for about 3 hours and could have penetrated deeply at the edges.
Room 2: Here I installed tiles, and the grout joints are in good condition. Also 8 cm (3 inches) of screed directly on the concrete slab, with perimeter insulation strips plus tile baseboards and silicone joints at the edges. I measure elevated moisture at three spots along the edges where the silicone joint was not closed (60 digits vs. 44 digits at other places in the room; dry tiles in another room show 35-40 digits).
The drying company claims I should simply leave the baseboards in place, and that over time the moisture will dry out through the grout and the bricks naturally. What do you think of this claim? The perimeter insulation strip is supposed to prevent moisture from the screed from penetrating into the bricks, isn’t it?
I am using a Trotec BM31 (ball head) moisture meter.
Thanks for your assessments!
my neighbor (terraced house) had a major water damage incident, and apparently the water came over the shared concrete slab into our property (the basements are separated by two hollow brick walls, waterproof concrete only on the outside). There was about 2 cm (1 inch) of standing water in our basement for approximately 3 hours.
The drying company started working immediately, but in two of our basement rooms, there is no insulation layer under the screed; it seems the screed is laid directly on the concrete slab, and there is no plastic membrane in between. Interestingly, at the edges, there is the typical plastic perimeter insulation strip usually found with floating screed. Does anyone understand why it was built this way?
Current situation:
Room 1: 8 cm (3 inches) of bare screed (no floor covering). After 3 weeks of drying with condensation dryers, the floor appears to be in good condition again. However, the edges are still more damp than the center, probably because the water was able to penetrate the concrete slab via the perimeter insulation strips. The bottom row of bricks (above which there is a horizontal damp-proof course) is also normalizing in moisture content (35 digits vs. 18 digits in the drier bricks higher up).
How do you assess the chances that it’s just a matter of time before the screed fully dries out? How long might this take? The water was in contact with the entire surface from above for about 3 hours and could have penetrated deeply at the edges.
Room 2: Here I installed tiles, and the grout joints are in good condition. Also 8 cm (3 inches) of screed directly on the concrete slab, with perimeter insulation strips plus tile baseboards and silicone joints at the edges. I measure elevated moisture at three spots along the edges where the silicone joint was not closed (60 digits vs. 44 digits at other places in the room; dry tiles in another room show 35-40 digits).
The drying company claims I should simply leave the baseboards in place, and that over time the moisture will dry out through the grout and the bricks naturally. What do you think of this claim? The perimeter insulation strip is supposed to prevent moisture from the screed from penetrating into the bricks, isn’t it?
I am using a Trotec BM31 (ball head) moisture meter.
Thanks for your assessments!
Hi,
In the past, it was common to install screed directly on the concrete slab without insulation. The perimeter insulation strip often served only as a separation layer for sound and stress, not as a moisture barrier. It makes sense that the edge areas take longer to stabilize, as moisture tends to accumulate there due to limited lateral escape. After three weeks, nothing is really decided yet—8cm (3 inches) of screed realistically needs about 6 to 10 weeks, especially when there is concrete underneath and no separating membrane. The moisture readings are more of an indicator of trend rather than an absolute truth, which you probably already know. I find Room 2 more critical; tiles significantly slow down moisture release, and the perimeter insulation strip not only prevents contact with the wall but also hinders drying. Very little drying occurs through joints; that is more of a calming theory. Honestly, I wonder why the drying company is so relaxed—perhaps because no visible damage is imminent.
In the past, it was common to install screed directly on the concrete slab without insulation. The perimeter insulation strip often served only as a separation layer for sound and stress, not as a moisture barrier. It makes sense that the edge areas take longer to stabilize, as moisture tends to accumulate there due to limited lateral escape. After three weeks, nothing is really decided yet—8cm (3 inches) of screed realistically needs about 6 to 10 weeks, especially when there is concrete underneath and no separating membrane. The moisture readings are more of an indicator of trend rather than an absolute truth, which you probably already know. I find Room 2 more critical; tiles significantly slow down moisture release, and the perimeter insulation strip not only prevents contact with the wall but also hinders drying. Very little drying occurs through joints; that is more of a calming theory. Honestly, I wonder why the drying company is so relaxed—perhaps because no visible damage is imminent.
What kind of potential hidden damage could there be? If something were to start molding down there, you would probably smell it, right? And in that case, the damage would already be visible and claimable? Or how does the warranty from drying companies work? I have zero experience with that, unfortunately. It involves a large company operating nationwide across Germany.
Invisible damage is unfortunately exactly the kind you can’t smell, at least not immediately. Mold needs oxygen and organic material; both are barely present in the screed, but in edge zones, layers of dust, or at the junction to the wall, it can be sufficient—especially if there is persistent moisture for months. The idea that you can always smell it is a common myth. Often, nothing happens for a long time, and eventually, discoloration or efflorescence appears, which no one then wants to connect to the water damage. Warranty claims with drying companies are tricky; they like to protect themselves with measurement reports. Digital readings are often used internally, even though they have little physical meaning. If the baseboards remain in place, drying takes a very long time. This can work but doesn’t have to. Time is the only factor here, and we’re talking about months rather than weeks.
Is there any way for me to protect myself against these measurement reports? For example, by hiring an independent surveyor? Or by disputing the reports with my insurance company? This is all handled through our building insurance, which in turn will seek recourse from the neighbor's liability insurance.
Yes, that is exactly the best place to start if you want to be on the safe side. An independent building expert or moisture assessor can verify how high the residual moisture really is, whether the edge areas are critical, and if the drying was carried out properly. These reports are usually taken seriously by insurance companies, especially when they are prepared promptly after the damage occurs. You cannot simply “ignore” the drying company’s protocols, but you can have them verified: comparative measurements at the same locations show whether the company is working correctly and whether the values are realistic. In a subrogation case against a neighbor, such a report can also help avoid disputes about the cause and extent of the damage. An important point is to involve your own expert preferably before the final drying, otherwise the critical areas might no longer be visible.
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