ᐅ Concrete slab without a screed layer on the upper floor/attic – what to do?

pagoni2020 schrieb:

We have a concrete ceiling throughout the whole house.
Depending on the type of flooring you want to install, you can simply use a dry build-up, and there are several options for that.
For example, in the bathroom we used loose fill insulation topped with Fermacell boards, then tiles on top. In the rest of the area, we laid battens floating on the floor, with Steico wood fiber insulation in between, and then screwed wooden floorboards on top. You can also screw OSB boards onto the battens and lay your flooring on that.
Why should that be a problem?
You don’t have to have the doors shortened – how many centimeters of floor build-up are currently possible on the upper floor?
What was the original plan, and why is it different now?

The site manager wrote to me that the distance from the top edge of the raw floor to the bottom edge of the door frame is about 11mm (0.4 inches). So, the doors and frames definitely have to be shortened. Some neighbors who installed parquet also had to do the same.
Everything actually corresponds with the original plan. We just didn’t know that there would be no screed on the upper floor/attic.

And yes, we are also dealing with developer-built townhouses (specifically German terraced houses).

KlaRa schrieb:

Hello "christophen".
Parquet is a building material with its own specific characteristics! It may look beautiful, but it reacts unlike any other material to changes in indoor humidity by expanding or contracting. Every type of parquet!

When it comes to concrete floors, it is important to note that they are usually finished with a surface flatness suitable for parquet installation (neither floating nor fully glued). This means mechanical preparation is necessary, such as shot blasting or grinding, followed by priming and then leveling with a self-leveling compound.

That would give you a smooth (installation) substrate, but the moisture trapped inside the concrete from the mixing process escapes very slowly and will migrate to the part of the room with the lowest humidity potential for at least 2 to 5 years.

To put it simply: In the years following the freshly poured concrete, it will release the water used in mixing into the room air above. The parquet will absorb this moisture, causing it to expand or even warp.

Therefore – in my opinion – you should abandon the idea of direct installation. Tiles can be glued directly onto a concrete subfloor without issue, but parquet carries an unpredictable risk of future floor damage due to deformation!

For this reason, every professional parquet installer should refuse the project of installing parquet directly on concrete.

The safest and most damage-proof method is to use a floating screed. This also complies with the technical regulations, all of which are based on a screed as the installation substrate.

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Regards, KlaRa

Thank you for your contribution. Would you also advise against installing parquet as a floating floor? Because then there would be a membrane or underlay for impact sound insulation underneath. In that case, the parquet shouldn’t be able to absorb moisture, or am I completely mistaken?

christophen schrieb:

The construction manager wrote to me that the top edge of the rough floor to the bottom edge of the door frame is about 11mm (0.4 inches). So the doors and frames definitely need to be shortened; some neighbors who installed parquet flooring had to do the same.
Everything actually matches the original plan. We just didn’t know that in the upper floor/attic there would be no screed.

And yes, in our case it is also a developer-built terraced house (specifically German terraced house).

Did the construction manager also mention in which parallel universe this complies with the “generally recognized rules of technology”?

christophen schrieb:

Everything actually matches the original plan. We just didn’t know that we wouldn’t have screed on the upper floor/attic floor.

This is actually said here almost daily, morning, noon, and night: if something is not included in the construction specification, it will not be part of the house. And that there are professional construction specification readers you should consult as a layperson.

i_b_n_a_n schrieb:

Did the site manager also mention in which parallel universe this is executed according to the "recognized rules of technology"?

Considering the raw concrete ceiling surface as a finished floor is widespread in this house offer range, so much so that you could almost speak of a "commonly accepted practice"...

christophen schrieb:

And yes, in our case, it is also a developer-built townhouse (specifically Deutsche Reihenhaus).

... with such offers, you should keep in mind that large residential developers know their target group (not only first-time buyers but also their successors!) very well and have carefully considered deliberately not providing screed (and underfloor heating) on the upper floors. Perhaps they should take a more active role in guiding their customers and explain that their standard specification is often misinterpreted if seen as something to “upgrade yourself.” Installing hand-stitched leather seats in a Dacia will not be appreciated on resale. Many buyers apparently still have to learn to read “no screed” as a warning recommendation meaning “no hardwood flooring, no large-format tiles.”

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11ant schrieb:

This is actually said here almost daily, morning, noon, and night: if something is not included in the scope of work, it will not be part of the house. And there are professional scope of work readers you should consult as a layperson.

Considering the bare concrete ceiling surface as a finished floor is quite common within this range of house offers, so much so that you could almost call it "accepted practice"...

... with such offers, one should keep in mind that large housing developers know their target group very well (not only first-time buyers but also their successors!) and have carefully considered to deliberately omit screed (and underfloor heating) on the upper floors. Perhaps they should guide their customers more actively here and explain that their standard of equipment is misunderstood if they interpret it as "upgrade it yourself." Retrofitting hand-stitched leather seats in a Dacia won’t be appreciated in resale value. Many buyers unfortunately still need to learn to read "no screed" as a warning: "no parquet, no large tiles."

Most of the posts here don’t really help us move forward at all. There are thousands of people living in these types of constructions with certain disadvantages for years; in some countries, this is even the standard. I wanted to ask here how to make the best out of it.

It should also be clear that nobody who buys a Dacia expects at the end to have the framework of a Mercedes.

I understand that you are explaining everything with the best knowledge and intentions on how things should have been done in the past, but now it is too late, and as I said, most of the comments here unfortunately do not help us. We need recommendations for the future.

But thanks already for your explanations.

christophen schrieb:

I understand that you have explained everything with the best intentions and knowledge about the best way to proceed in the past,

A forum is not like a private consultation with a chief physician in a single room: I and many other advisors here do not write answers solely for the current, urgent questioner, but always also for the dozen silent readers who are following that visible questioner’s case (and who can definitely still be given an early hint).

christophen schrieb:

but now it is simply too late

Why should it be “too late” here to settle for a floor covering that fits the house?

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