Screed vibrates - tips for noise elimination

Hello everyone,

In 2021, we built a single-family house with an experienced timber builder. The architect had initially planned the house as a solid construction; we were persuaded by recommendation to have the house built as a timber frame construction since we waited over 1.5 years for the building permit approval and were convinced by the ecological and, above all, the fast construction method.

The house was erected in three days, and we then decided to manage the interior finishing ourselves with our own craftsmen. All materials for the interior finishing were provided by the house builder. Basically, we are satisfied with the house construction, but the big problem is the impact sound and vibration when walking. This is because we only had a 12cm installation height over the beams.

We thought that we could live with it eventually, but it is incredibly exhausting when you hear the dull noises in bed and the noise from the floor above is almost unbearable.

I would like to briefly show the construction of the ceiling from the ground floor to the upper floor. First of all, these are large beams measuring 24x10cm, spaced about 65cm apart (cavities filled with insulation material).
> Closed from below with battens and drywall panels
> A 19mm OSB board lies on the beams.
> A 40mm thick impact sound insulation (Pavaboard from the brand Pavatex) was laid on the OSB board.
> Of course, edge insulation strips were laid beforehand so that there is no contact with the wall anywhere.
> Then a Schlüter underfloor heating with low installation height was installed on top.
> The screed installer then applied a thin cement screed of approximately 20mm.
> A 14mm parquet floor was glued on as the floor covering, so that we have an overall installation height of 12cm, thus flush with the floor-to-ceiling doors.

The recommendation came from the timber builder, but he rejected any responsibility. The house was generally very expensive since we built it during the expensive construction phase in 2021 when the raw material prices exploded; the result is all the more disappointing. The children are growing, and as toe walkers, the impact sound is almost unbearable. These dull steps vibrate/oscillate all the way to the bed, and on the ground floor, it feels as if elephants are stomping above.

By now, we have reached the point where we would temporarily move out to fix this construction defect for a fee. We come from NRW and are looking for a specialist to identify the cause and manage the construction measures.

I look forward to information and help.
Thank you very much!

I am looking forward to information and help

Sounds like the OG ceiling is working like a drum. Thin surface and a decent resonance chamber underneath. No immediate solution, due to lack of experience with the framework. Perhaps replacing the insulation in the cavities with a more solid variant.

Hello questioner,

Regarding the basic structure of the floor construction, the concept chosen at the time seems plausible to me. Except for the impact sound insulation layer. If we look at the technical data sheet "Pavaboard", we find the following manufacturer’s note: "This wood fiber insulation, with the very high compressive strength of 200 kPa, is ideally suited for constructing highly load-bearing dry and also wet screed constructions." ------------------ Ideally - as impact sound insulation - materials like mineral wool or - for reasons of fire safety - glass wool are used for timber frame constructions. These are compressed boards. Now let us look at the text from the product description PAVABOARD. It states that this underlay/board has a very high compressive strength of 200 kPa at 10% compression (note: normative requirement during testing). Even a layperson must now take notice: a high compressive strength always means a high material density. And the principle of impact sound insulation is that the sound should be able to be "neutralized" as much as possible within the material. The harder/denser a material is, the higher its material density, the worse its ability to absorb sound energy. Well, at this point, before the critics shout, the justified note that every material used for impact sound insulation can only absorb specific sound frequencies. This can mean that one material absorbs only high frequencies, another more low frequencies. Back to the product data sheet: This gives a compressive strength of 200 kPa for the underlay "Pavaboard." Now let us compare this with the product data sheet of a mineral wool impact sound insulation. There we find a compressive stress, depending on the insulation type, between 5 kPa and 40 kPa. This means that this impact sound insulation can absorb significantly less stress than "Pavaboard". However, a functioning impact sound insulation is characterized precisely by not being able to absorb large stresses, but by converting them into deformation due to its "springy" properties. (I hope I have been able to express myself understandably on this rather difficult topic.) Meaning: from my point of view, the impact sound insulation underlay used in timber frame construction should not have been used, but rather glass or mineral wool. ---------------------------- What now arises at or from this point is the question of the further procedure. From my own practice, I can say with almost absolute certainty that due to the presumably high cost of the renovation, an agreement between the parties and those responsible will not be possible. There will be a legal dispute, during which the judges will involve an expert in sound insulation. And his/her measurements will provide a very clear statement about the situation. I myself had to handle a similar case as an expert in a legal matter. Since sound insulation is not one of my specialist areas, I obtained the court’s permission to involve an expert in sound insulation. This was approved, and I was amazed at what technical conclusions can be drawn from the measurement curves obtained!! This means: without a sound insulation expert and his/her measurements, there will certainly be no decisions. ----------------- Sorry for this "bad" news: KlaRa

Sounds like the OG ceiling works like a drum. Thin surface and underneath a proper resonance chamber. No ad hoc solution due to lack of experience with the studwork. Perhaps replacing the insulation in the cavities with a more massive variant.

Hello nordanney, thank you very much for the assessment, I also suspect that it is some kind of resonance chamber because the thin screed layer lies on the lightweight studded panel of the underfloor heating. We have also already considered insulating the cavities with concrete.

I am looking for an expert / soundproofing specialist who can expose this and then recommend a reliable construction.

I look forward to hearing from you.

Thank you

Sorry for this "bad" news: KlaRa

Hi KlaRa, thank you for the extensive information. The message is not bad, we are aware that a costly repair is necessary, we would also allocate time for it, of course. We just want a solution.

However, Pavaboard is widely used for subfloors, the carpenter uses it in almost every house and the supplier also recommended it as a subfloor. Isn't glass wool ultimately too soft?

PAVABOARD is excellently suited under all kinds of screeds, dry screeds as well as pre-finished parquet and laminate. Due to its high compressive strength, the board is ideally suited for applications with high loads.

We do not want any legal dispute or lawsuit, as it was ultimately our decision to use it based on recommendation, so as written above, not a turnkey prefab house solution.

Does anyone know addresses of experts who can assess this and ultimately also manage the soundproofing repair?

Thank you very much in advance!

A carpet instead of parquet would also help.