Question 1

Closed acoustic ceiling or ceiling rafts?

Accepted Answer

A closed acoustic ceiling covers the full area and delivers the highest, most even absorption. It is the baseline for demanding rooms such as open-plan offices, classrooms or canteens. Partial coverage with surface panels or rafts treats only part of the ceiling but is cheaper, easier to retrofit and suits exposed-concrete or industrial looks.

Rafts and baffles hang freely in the room and work on both sides, top and bottom. As a result they reach high values relative to the area covered, even when only part of the ceiling is treated.

Question 2

What percentage of the ceiling should I cover?

Accepted Answer

A closed acoustic ceiling covers almost the full area and is the benchmark. With partial coverage using rafts or panels, around 40 to 70 percent of the ceiling area is often needed to bring the reverberation time into the target range. The exact figure depends on room height, use and the products' αw values.

Question 3

Does the air gap of a suspended ceiling improve bass?

Accepted Answer

Yes. The cavity between absorber and structural ceiling shifts the effective absorption to lower frequencies, because the enclosed air volume resonates with it. The larger the gap, the lower the effect reaches. The same absorber therefore reaches better low-frequency values with an air gap than mounted directly. The mounting type is stated with each reverberation-chamber dataset.

Question 4

Should I combine ceiling and wall absorbers?

Accepted Answer

Treat the ceiling first, because as the largest free surface it delivers the most per square metre. If that is not enough, or if direct reflections between speaker and listener cause problems, wall absorbers are added precisely. The combination of a damped ceiling and targeted wall areas usually gives the best result per square metre invested in larger rooms.

Question 5

How does an acoustic ceiling relate to reverberation time?

Accepted Answer

Reverberation time has target values depending on room use and volume. An acoustic ceiling is usually the most effective measure for reaching these targets. From the αw values and the area covered, the resulting reverberation time can be calculated. The Acoustic Index reverberation calculator uses each product's stored measurement data directly.

Question 6

What fire class does an acoustic ceiling need?

Accepted Answer

The decisive figure is the fire class, which ranges from A1 (non-combustible) to F. Escape routes and many public buildings require non-combustible ceilings, often A1 or A2. In ordinary offices and homes the requirements are lower. You can filter by minimum fire class in the search.

	Effect	Typical αw	Mounting	Best for
Closed acoustic ceiling	Maximum, even absorption across the full area	0.9–1.0	Full-area, surface-mounted or suspended	New build, open-plan offices, high demands
Suspended ceiling with cavity	Broadband plus better low-frequency effect from the air gap	0.9–1.0	Suspended with a gap to the structural ceiling	Rooms with services, low frequencies
Surface-mounted panels (direct)	Partial ceiling coverage, easy retrofit	0.8–1.0	Glued or screwed directly to the ceiling	Existing buildings, low rooms, partial refits
Rafts / baffles (islands)	Targeted over zones, effective on both sides	0.8–1.0 (per covered area)	Freely suspended, single or in a grid	Exposed concrete, industrial look, flexible zones

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