Screed drying apparently extremely slow

We received our cement screed on June 6th/7th. The screed then rested for 3 weeks with (1-3 times ventilation per day). This was followed by the 3-week heating program with correspondingly varying temperatures. Afterwards, another week was heated at a moderate temperature. By mid-August, the living room (intensive sunlight from 7 a.m. to 2 p.m.) was ready for covering. The other rooms (bedroom, children's room, etc., all with less sunlight) were still too damp. So, another 2 weeks of intensive heating and ventilation 3-4 times a day were done. The weather was of course not particularly helpful (very humid and still fairly warm at 20-26°C most of the time).

In the meantime, the screed has been in place for over 3 months or 14 weeks and the flooring installer measured values between 2.0 and 2.4 CM for the rooms. According to my understanding, we want to achieve <1.8 CM. Actually, values below 2.0 were measured already 2 weeks ago and today the values were above that again.

We moved in last weekend and would of course like to finish and use the rooms.

What can we do to achieve readiness for covering?

Hi,
why haven't you set up any [Bautrockner]? You can hardly get the moisture out of the house just by airing, especially in summer.

Rent / buy 2-3 [Bautrockner] and get started.

Best regards,

Andreas

Hi,
why haven’t you set up any dehumidifiers? Just airing out alone makes it difficult to get rid of moisture from the house, especially in summer.

Borrow / buy 2-3 dehumidifiers and get started.

Best regards,

Andreas

No one had recommended that so far and until now we assumed it would no longer be necessary (until the moisture values stagnated/increased again). My initial research showed €40/rental day per unit. That means ~€550 for 2 units for one week. That’s really steep.

But those things do manage pretty significant amounts, right?

We once had a similar case here where the tiler just wanted to waste time, probably too much work.

Ps. add a lot of power for the [Bautrockner].

Hello questioner. Basically, I do not trust any CM measurement that I have not conducted myself. A standard cement screed without additives will reach readiness for laying at a thickness of 45mm and under the current (outdoor) climate conditions within about 6 weeks, provided that good and regular ventilation was carried out in the meantime. However, in screeds where additives have been used, it is quite possible that readiness for laying can be considered dry even with a CM residual moisture value above 2.0%. The definitive answer to this can be given by the screed installer who installed the screed and possibly used an additive. Please stay away from drying devices with a young screed! The disadvantages frequently arising from these can be considerable. It is better to set up several fans for proper air circulation and leave the windows of the rooms slightly open in the meantime. You can check yourself whether the screed actually still contains too much residual moisture. In two rooms, stick the edges of a thicker PE film measuring 50cm x 50cm each onto the screed with textile adhesive tape. Place an ordinary hygrometer, which deserves this name, under the foil beforehand. Now open the windows for ventilation and check after about 24 hours whether condensation has formed under the foil. Then the residual moisture would still be too high. If no condensation forms, look at the scale of the hygrometer. If the value is clearly below 70%, then the screed is very likely sufficiently dry for the installation of textile coverings. For elastic coverings and parquet, the value should not be higher than 65%. Critics may now raise their voices loudly, but with this method one can really obtain a very good estimate! --------------------- Regards: KlaRa

Please keep your hands off drying devices with a young screed! The disadvantages that may often arise from this are considerable.

Until when is a screed considered "young"? It has now been 15 weeks since installation. Today the floor layer is back and measured 1.8-1.9. The installation will now take place.