ᐅ Drying time of screed before applying leveling compound

First of all, hello to everyone :-)

I have already read a lot on this forum, but this is my first post because I haven’t found an answer to my current question.

Six days ago, I used screed concrete for the first time. Unfortunately, it didn’t turn out as level as I had hoped, and now I want to even it out with a self-leveling compound. The thickness of the screed is 7cm (2.8 inches). I have read that full drying takes at least 7 weeks (1 week per cm). Do I need to wait for this period, or can I already apply the leveling compound? Or will it seal the surface and prevent all moisture from escaping the concrete?

In the end, we want to lay tiles.

Thanks for your help.

Regards

Robinson

Hello Robinson

It is advisable to wait with the leveling.
The screed must first dry out. If a primer is applied now and another impermeable layer is placed on the screed, the drying process will be delayed.
The drying time depends largely on the density of the screed and the relative humidity.
There is a general rule of thumb that says: the first two centimeters (1 inch) take one week, and each additional centimeter (0.4 inch) takes two weeks.
Before laying the tiles, the screed must be checked to ensure it is fully dried and ready for covering.

Truttmann schrieb:
There is a rule of thumb that says: the first two centimeters (0.8 inches) require one week, and each additional centimeter (0.4 inches) requires two weeks.
Before laying the tiles, the screed must be tested to ensure it is ready for covering.

Good evening,

We are currently trying to figure out when the flooring company can finally install the parquet. We don’t even know how thick the screed is. According to the flooring company, the residual moisture is still far too high.

So our first priority is to clarify how thick the screed is in our case. Our main question to the experts now is: does the mentioned rule of thumb apply to all screeds, meaning both cement-based and anhydrite screeds?

Thanks for your information.
mk

I was hoping for an answer to my question.

Can anyone here maybe help me out?

Thanks

Hello Merkur,
Anhydrite and cement screeds each have different drying behaviors; this is based on their different binders: gypsum (anhydrite) in one, cement in the other screed.

The parquet installer should wait for the floor to be ready for covering (i.e., the degree of dryness); for cement screed, the maximum moisture content for parquet readiness is 2.0%, and for anhydrite screed, it is 0.5%.

To manage the interior construction schedule, it would be useful to know the thickness of the screed. It is usually around 40–45mm (1.5–1.75 inches) in residential construction, which results in a drying time of about 3–4 weeks.
However, the drying behavior of screeds depends not only on the composition and thickness but also significantly on the installation methods, the start of drying, and the drying conditions (which is a science in itself).

Hello again,

The installation company still says it will take a while because the parquet flooring is being laid on an anhydrite screed with underfloor heating, and that a maximum residual moisture level of 0.3% must be maintained.