Celenit N and Sound Absorption: What the Datasheet Does Not Declare
Celenit N is the most widely sold board in the Celenit range and the cheapest. It is a good product doing the job it was designed for. It is also the source of the most common and most expensive specification error we see in mineralised wood wool, which is people buying it for acoustics.
This is not a criticism of the board. It is a criticism of how it gets specified, and the fix is simple once you know what to look for.
Start with the document
Open the Celenit N scheda tecnica and look for the sound absorption row.
It is not there.
The datasheet declares thermal conductivity, 0.065 W/mK, the best in the Celenit range. It declares mass, 11.5 kg/m2 at 25 mm. It declares compressive stress at 10 percent deformation, water vapour resistance factor, specific heat, chloride content, a Euroclass of B-s1,d0 and a full EN 13168 designation code. It is a thorough datasheet.
There is no alpha w. No NRC. No SAA. No absorption class. No octave band values. No certificate number.
This is not an oversight in one edition. It is consistent across the Celenit N datasheet, both of Celenit's technical manuals, the price list and the website product page. The Celenit AB and ABE pages in those same documents all carry an "Assorbimento acustico" row. The N pages simply do not have one.
Why not
Because of the wood wool width, and this is where the product actually makes sense.
Celenit N is made with 3 mm wood wool. Celenit AB uses 2 mm and ABE uses 1 mm. Finer wood wool gives a denser, more tortuous surface structure with smaller pores, which is what makes a porous absorber work. Coarse 3 mm wool produces an open, rugged board that is excellent as a substrate, as insulation, as a plaster carrier and as a lost formwork panel. It was never built to be an absorber, so Celenit does not test it as one and does not declare it as one.
That is a defensible engineering decision by the manufacturer. The problem happens downstream.
Where it goes wrong
A room needs acoustic treatment. Somebody specifies "Celenit", which everyone in Italy understands to mean wood wool acoustic panels. A quantity surveyor prices the range and finds N at 17.76 EUR per square metre against AB at 27.24, both for 25 mm natural board with a straight edge on the January 2023 list. The cheap one gets ordered. It arrives, it looks like wood wool, it is fixed to the ceiling.
Then the room is measured, and the reverberation time is not what the acoustic report predicted.
At that point there is no recourse, because the manufacturer never claimed an absorption coefficient. The claim was invented somewhere between the datasheet and the purchase order. Nobody was misled by Celenit. The specification was simply written against a product that does not declare the performance it was bought for.
There is one wrinkle worth flagging for anyone reading the documents closely. Celenit's price list describes N as conforming to both UNI EN 13168 and UNI EN 13964. EN 13964 is the suspended ceiling standard. The N datasheet and the technical manual both cite EN 13168 only. If you are relying on an EN 13964 declaration for a ceiling application with Celenit N, get that confirmed in writing from the manufacturer rather than from the price list.
What Celenit N is genuinely good at
To be clear, because this is a real product with real uses:
It has the lowest thermal conductivity in the Celenit range at 0.065 W/mK. It is the only Celenit board offered up to 75 mm thick. It takes plaster and render well, which is its classic role as a bonded substrate. It is structurally robust at 200 kPa compressive stress. It is B-s1,d0. And it is the cheapest board Celenit makes.
If you want insulation, a plaster carrier or a robust lining, Celenit N is a sound choice and this article is not arguing otherwise. If you want absorption, it is the wrong item number.
What to specify when the room needs acoustics
You need a board with fine wood wool and, just as importantly, a published test at the mounting condition you are going to build.
Within the Celenit range that means AB or ABE rather than N. AB 25 mm on a 200 mm empty cavity gives alpha w 0.65, Absorption Class C, under Istituto Giordano certificate 331332-D. ABE 25 mm at the same buildup gives alpha w 0.65, Class C, under certificate 331334-F. Both are real, both are documented, and both cost more than N for exactly that reason.
The Sonablock equivalent is the Core range. Sonablock Fiber 1.5 at 25 mm on a 200 mm empty cavity gives alpha w 0.65 with an H shape indicator, Absorption Class C, tested by RISE Research Institutes of Sweden to SS-EN ISO 354 and classified to SS-EN ISO 11654 under report O100282-1356156. Fiber 1.0 at the same buildup gives alpha w 0.60, also Class C.
Which is to say: at the same thickness on the same cavity, Celenit AB, Celenit ABE and Sonablock Fiber 1.5 all measure the same. That is what you would expect from the same material at the same geometry. The meaningful difference is not the absorption coefficient. It is the price, the lead time, and whether you can get hold of the underlying report.
On that last point, Sonablock publishes the full RISE PDF, including the one third octave curve, the chamber dimensions, the temperature and humidity at the time of test and the signatures of the engineers who ran it. Celenit publishes certificate numbers but not the reports behind them.
Do not compare absorption figures without the mounting condition
The other half of the problem is that even correctly specified wood wool gets compared badly, because absorption figures for this material are close to meaningless on their own.
Here is Celenit AB at 25 mm, the same board throughout, at different buildups:
| Mounting | alpha w | Class |
|---|---|---|
| Fixed flat to the slab | 0.45 | D |
| 30 mm cavity | 0.45 | D |
| 100 mm cavity | 0.60 | C |
| 200 mm cavity | 0.65 | C |
| 30 mm cavity with 80 kg/m3 mineral wool | 0.75 | C |
| 200 mm cavity with 30 mm of 80 kg/m3 mineral wool | 0.90 | A |
Class D to Class A, from the same panel. The cavity is doing most of the work.
This is why Celenit's front page headline of "alpha w up to 0.95" for AB is technically accurate and practically misleading if it is read without the footnote. It requires a filled cavity. Celenit's own website segments the claim properly, giving separate values for direct fixing, empty cavity and rock wool filled cavity, so the honest version is published. It is just not the version that travels into tender documents.
The same caution applies in our direction. Sonablock's published alpha w 0.65 is an empty cavity figure. Put mineral wool behind a Sonablock panel and it will climb the same way, for the same physical reason, but we do not publish a filled cavity number because we do not yet have a filled cavity test to hand you.
A four line specification that prevents all of this
Whatever brand ends up in the room, write these four things down:
- Board thickness in mm, and the wood wool width
- Cavity depth in mm
- Cavity contents, either empty or the thickness and density of the mineral wool
- The required alpha w and absorption class at that exact buildup, with the certificate number that supports it
If a datasheet cannot give you point four for the product being offered, that product has not been tested for what you are buying it for. That is the whole of the Celenit N story, and it applies equally to anyone else's board.
Summary
Celenit N declares no sound absorption performance at any thickness, in any of Celenit's published documents, because its 3 mm wood wool was never designed to absorb. It is a capable insulation and plaster carrier board and it is priced accordingly.
If the room needs acoustics, specify a fine wood wool board with a test report that matches your buildup. Celenit AB and ABE do that. So does Sonablock Core, at the same measured alpha w 0.65 and the same Absorption Class C, with the test report available to download.
Sources
- Celenit N technical data: CELENIT N scheda tecnica ed. 2018/11, and Celenit ISOLAMENTO INVOLUCRO technical manual ed. 00 rev. 02, 2020/10
- Celenit list prices: LISTINO PREZZI Gennaio 2023, ed. 00 rev. 00, in force from 1 January 2023
- Celenit AB 25 mm, TH 225 empty cavity: Istituto Giordano certificate 331332-D, 11 February 2016
- Celenit ABE 25 mm, TH 225 empty cavity: Istituto Giordano certificate 331334-F, 11 February 2016
- Celenit AB mounting series at 25 mm: Istituto Giordano certificates 331332-A, 331332-B, 331332-C, 331332-D, 333104-A, 324214-B, 324215-E
- Sonablock sound absorption: RISE Research Institutes of Sweden, report O100282-1356156, 3 March 2026, to SS-EN ISO 354 and SS-EN ISO 11654. Published in full at wallpanelspro.com Sonablock documentation
