What is the Highest STC Rating?

The highest STC rating mentioned in the provided reference is 65.

Understanding STC Ratings

STC stands for Sound Transmission Class. It is a single-number rating system used to measure how effectively a building material or assembly, such as a wall, floor, or window, blocks airborne sound. The higher the STC rating, the better the material or assembly is at reducing sound transmission.

The STC Scale: 25 to 65

According to the reference, the STC rating goes from 25 – 65. This range illustrates the spectrum of soundproofing capabilities:

• A rating of 25 is no soundproofing.
• A rating of 65 is complete soundproofing.

For context, a standard single-pane window, often offering minimal sound blockage, would typically have an STC rating of 25.

The principle is simple: the higher the rating, the less noise penetration.

Practical STC Levels

While 65 is presented as the upper limit for "complete soundproofing" in this specific context, achieving very high STC ratings in real-world construction often involves complex and multi-layered assemblies.

Here's a general idea of what different STC ranges typically represent:

• STC 25-35: Normal speech is easily understood. (e.g., single-pane window, thin interior wall)
• STC 35-45: Loud speech is audible but muffled. Normal speech is difficult to understand. (e.g., standard interior wall with drywall)
• STC 45-55: Loud speech is barely audible or inaudible. (e.g., well-constructed wall, insulated wall)
• STC 55-65+: Very loud sounds are significantly reduced or inaudible. (e.g., specialized soundproof walls, double-wall construction with air gaps and insulation)

Based on the provided reference, the highest value on the STC scale is 65. This represents the maximum level of soundproofing within the stated range.