Screed does not dry after 10 weeks of laying + heating program

Thank you for your detailed feedback. I don’t want to offend my tiler, he also has a few years of experience and he said that according to his experience, with his measuring device, usually anything over 60 digits doesn’t achieve the 1.8%? residual moisture, which I believe is required for cement screed. It’s not that picky if a few per mille are missing to lay tiles. For parquet, he would of course be more precise. But as I said, the screed could still sit for a few more weeks. As mentioned at the beginning, since the screed was installed, 2 hygrometers have been distributed throughout the house. Last week both hygrometers mostly showed a level between 20%-30%. One of the two devices even recorded 14% humidity below minimum. So since our "special program" has run, the humidity hasn’t been above 40% anymore, I believe. But as I said, we were generally always below 30%, at the latest when shock ventilation was done. I have to say though that this week the painters were in the house, finished today, and currently the humidity is about 55%. But I don’t think that will disturb the screed now. Of course, it does affect the attempt of your measurement. That’s why I’m giving the data from last week! I would now let it run until Sunday evening and order the CM measurement on Monday. Or is it already unnecessary based on the data? I will not be charged for the measurement anyway. He just doesn’t want to “sell me short” on the screed. That’s it. Hope for a response. Thank you.

Let's start with the last point: he, the tiler, does not want to hammer down the screed. Completely unfounded, you cannot "hammer down" a screed. If 10 measurements were necessary, 10 correspondingly small test openings would be needed, which would be resealed with quick-setting mortar before the floor covering work. Experience aside, if the hygrometer shows a validated value < 50%, the screed or other mineral components no longer release moisture into the room air. However, you should hold the hygrometer once (taking your own safety into account, of course) in the steam of a pot of boiling water. After about 5 minutes, a value well above 90% should be displayed. Place the hygrometer beforehand (!) for about 2 hours in the refrigerator. The value should be around 10%. This is a kind of "quick calibration" to be able to recognize whether the values displayed on the device’s scale are approximately correct. --------------- When the floor layer carries out the CM measurement, please make sure that the following parameters are documented: a) Depth of the test opening in cm b) Sample weight in g (for cement screeds it should be 20g up to a maximum of 50g). c) Did the floor layer touch the sample with his fingers during extraction d) Duration of the measurement in the pressure vessel e) Was the sample or the pressure vessel gently shaken in the meantime (during the measurement phase)? f) What value did the manometer show in bar? g) What CM residual moisture did the tiler then record as the final value? -------------------------- These details are important!! Simply writing down a value, for example 1.8%, is by no means sufficient for documentation!! Ultimately, a short note should also be made in the measurement protocol (to be created by the floor layer and handed over to the client) indicating exactly where the measurement point was located. Not as simple as one might think. Let’s hope the fuss was for nothing, that you hired a competent craftsman, and that the trade "Fliesen- und Plattenarbeiten" remains permanently free of damage! Regards: KlaRa

Thank you for the detailed answer, but I think the humidity is still too high anyway because of the painters.. although last night it was already 49% again. I will probably test it tomorrow. CM measurement has already been ordered.

So, quick feedback. We conducted the CM measurement today, even though the GANN was still almost everywhere above 60 digits. The CM measurement ultimately resulted in 1.9, tomorrow I will pick up my tiles, Friday it's starting. He followed everything as described. Took 50 grams with the spoon from the cross-section of the screed, shook for 2 minutes, waited 5 minutes, then shook again for 1 minute, 1.9; done.