What Are the Disadvantages of Acoustic Panels?

The biggest disadvantage of acoustic panels is that they don't block noise. A 2 in. fiberglass panel weighs about 0.5 lb/sq ft (Owens Corning 703 (opens in a new tab) is 3.0 lb/cu ft). Compare that with a full 2.2 lb/sq ft layer of drywall, which only took an insulated wall from STC 34 to 37 in USG lab tests (opens in a new tab).

The other disadvantages of acoustic panels are smaller, and you can dodge most of them by buying the right panel:

• Thin panels miss bass. 1 in. of 703 soaks up 0.88 of the sound at 1,000 Hz, but only 0.05 at 125 Hz.
• Untreated foam burns fast. In the Station nightclub fire investigation, "a non-fire retarded foam sample purchased by NIST ignited within 10 seconds" of a pyrotechnic spark (NIST (opens in a new tab)). Only buy foam that has a published fire rating.
• Paint can halve absorption. Rolling on paint took a 2 in. Primacoustic Broadway panel from NRC 1.00 down to 0.50, while a light spray left it at 1.05 (Primacoustic (opens in a new tab)).
• Bare fibers irritate. Loose fiberglass and mineral wool fibers can bother your eyes, nose, throat and skin, though the effects "disappear shortly after exposure stops" (ATSDR (opens in a new tab)). Stick with fabric-wrapped panels.
• They're on show. Panels stick out from the wall, and the fabric-square look doesn't suit every room; see are acoustic wall panels outdated.

If the noise is coming from a neighbor or the street, skip the panels. Seal the gaps, then add mass and decoupling. The soundproof panels guide shows what blocks sound, and the soundproof panels FAQ covers what you'll probably ask next.