Which PET Panel Thickness Should You Choose?
Felt panels are made in 6, 12, 18 and 24 mm. Thicker absorbs more low frequency — but the mounting gap often matters more than the thickness itself.
CYC Acoustic Team
CYC Acoustic Panel Specialists
Thickness is the first question most people ask and the second thing that actually matters. Here is how to choose properly.
The short answer
- 6 mm — light control. Takes the edge off a small room, backdrops, headboard walls, decorative panels in places that need some softening.
- 12 mm — the general-purpose choice. Most offices, meeting rooms, home studios and interiors.
- 18–24 mm — where low-frequency content matters and there is room for a deeper panel.
Why thickness is not the whole story
A porous absorber works by letting sound into a structure where friction converts movement into heat. Two things drive how well it does that:
- How deep the material is — thickness.
- How far the material sits from the hard wall behind it — the air gap.
The gap matters because the air in front of a wall moves most at a quarter wavelength. Moving the panel even a short distance off the surface puts the material where the air is actually moving, which is why a modest panel on battens can outperform a much thicker panel glued flat.
Practical consequence: a 12 mm panel on 25 mm battens can absorb meaningfully more than an 18 mm panel fixed direct. If your wall can afford a cavity, use it before you spend more on thickness.
Matching thickness to the problem
| Symptom | Start here |
|---|---|
| Small room sounds bright or boxy | 6–12 mm, direct-fixed, generous coverage |
| Speech intelligibility is poor in a meeting room | 12 mm on battens, plus a ceiling treatment |
| Music sounds muddy, bass builds up in a corner | 18–24 mm, on a cavity, across corners |
| Long narrow room with flutter echo | 6–12 mm on two opposing surfaces |
Coverage generally beats thickness. Treating 60% of a ceiling with a moderate panel usually does more than treating 15% of a wall with a deep one — because the goal is to interrupt as many reflections as possible.
Always quote the mounting condition
NRC is measured to ASTM C423 and depends on thickness, mounting and the test laboratory. So a specification that says "NRC 0.85" without saying how it was mounted is not a specification. Write it as the value, the mounting method and the standard — every time.
Order of operations
- Describe the acoustic problem in plain language
- Choose coverage area first
- Choose mounting method second (cavity or direct)
- Choose thickness last, within the depth you can afford