What Does STC 44 Mean for a Wall?
When you want a quiet meeting room, the number to look at is how much sound a wall blocks. This is called sound insulation. It is measured as STC in North America and Rw under international rules. A higher number blocks more.
What did we test?
A lab called CSIR National Physical Laboratory tested a 100 mm wall partition. It was made of BIOMEBOARD™ layers on both sides of a 50 mm rockwool core. The result was Rw 44 dB. Worked out the American way, the same data gives about STC 44. Important: this number is for the whole wall, not for one sheet of board. A different build will give a different result. The lab also tested a small sample, so a wall built on site may do a little worse.
What does 44 feel like?
In general terms, a wall rated around 44 makes loud speech hard to understand on the other side and cuts normal conversation and background noise a lot. It is a common level for meeting rooms and office cabins. It is not enough for places that need serious privacy, such as recording studios, music rooms or cinemas. Those need much higher numbers.
Why do low sounds get through?
Test results by pitch:
- 100 Hz (deep hum): 15 dB
- 500 Hz: 38 dB
- 1000 Hz (voice): 48 dB
- 4000 Hz (high sounds): 55 dB Low sounds pass through walls more easily because long sound waves shake the whole wall. This is true for most partitions of this type.
Insulation is not absorption
Do not mix these up. Insulation stops sound crossing a wall. Absorption reduces echo inside one room. This test only measured insulation.
How to get the best result on site
- Seal every gap, including edges and sockets.
- Carry the wall up to the true ceiling slab where possible.
- Do not place back-to-back sockets.
- Allow a safety margin, because sound can travel around a wall through ceilings and floors.
Common mistakes when buying a partition
- Choosing by thickness instead of by tested rating.
- Leaving gaps at the edges, top and sockets.
- Mixing up blocking noise and absorbing echo.
- Assuming the lab number will match the site exactly.
- Forgetting doors and glass, which are often the weakest parts.
FAQs
What is STC?
A single number for how well a wall blocks airborne sound.
What is the difference between STC and Rw?
They are very similar scales. STC is American, Rw is international. Results can differ by a point or two.
Is STC 44 good?
It is fine for offices and meeting rooms, but not enough for studios or cinemas.
Does this mean BIOMEBOARD™ absorbs sound?
No. This test measures blocking, not absorbing.
Can I get the full report?
Yes. Request it.
Do doors and glass matter?
Yes. A door or glass panel is often the weakest part of a wall, so a good wall with a poor door will still leak sound.
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