When you want to create quiet, comfortable spaces—whether at home, in an office, or in a commercial building—understanding STC ratings is essential. But what exactly is an STC rating, and why does it matter when you choose soundproofing solutions?
This guide explains everything you need to know about Sound Transmission Class (STC), how experts measure it, and what it means for reducing noise in your space.
What Is an STC Rating?
STC stands for Sound Transmission Class, a numerical rating that shows how well a building material or system (like a wall, window, or door) blocks airborne sound. Put simply, a higher STC rating means stronger soundproofing.
Think of it this way:
-
Low STC rating = Poor soundproofing (you’ll still hear a lot of noise).
-
High STC rating = Strong soundproofing (you’ll hear much less noise).
How Do Experts Measure STC Ratings?
Labs measure STC ratings by playing sounds at different frequencies on one side of a partition and recording how much sound passes through to the other side. Standards set by ASTM International keep these measurements consistent and reliable.
Here’s what the ratings mean in real-world terms:
-
STC 25–30: Normal speech easily passes through the partition.
-
STC 35–45: Loud speech is noticeable but harder to understand; therefore, this range works well for offices or moderately noisy areas.
-
STC 50–55: Conversations stay private at normal voice levels. As a result, this level serves as the minimum for shared walls in multi-family housing.
-
STC 60–65: Loud sounds barely get through. For this reason, these ratings are ideal for high-privacy spaces such as conference rooms.
-
STC 65+: Exceptional soundproofing where most sounds remain virtually inaudible—perfect, for instance, in sensitive environments.
For comparison, a typical interior wall rates around STC 30–35. By contrast, high-performance soundproofing walls can reach STC 55 or more.
Why Do STC Ratings Matter?
Understanding STC ratings helps you choose the right solutions for your space.
-
In homes, higher STC ratings block noise in bedrooms, media rooms, and between floors.
-
Within offices, strong STC ratings protect privacy and reduce distractions in open layouts.
-
For restaurants or hotels, good sound control creates comfort and enhances customer satisfaction.
Ignoring STC ratings, on the other hand, often leads to noisy, distracting, or uncomfortable environments.
How to Improve STC Ratings in Your Space
If your walls, ceilings, or windows don’t block enough sound, you can upgrade them to raise their STC ratings. Several professional soundproofing solutions work effectively:
-
Add Mass: Heavier materials like mass loaded vinyl (MLV) block more sound.
-
Decouple Structures: Resilient channels or sound isolation clips reduce vibrations that carry noise.
-
Seal Gaps: Even small cracks or openings let sound through—acoustic sealants prevent leaks.
-
Upgrade Windows & Doors: Specialized soundproof windows and solid-core doors dramatically improve STC ratings.
👉 Explore our soundproofing services at Hush City Soundproofing to see how we help clients achieve the right STC rating for their space.
Final Thoughts
In summary, STC ratings play a critical role in improving your space’s acoustic performance. The right materials and solutions help reduce unwanted noise, boost comfort, and create a more productive environment.
At Hush City Soundproofing, we specialize in helping homeowners and businesses block, absorb, and control sound. Our experts work with you to find the best solution—whether your goal is to soundproof a room, cut echo, or upgrade windows for noise control.
👉 Want to improve your building’s STC rating?
Contact Hush City Soundproofing today to get started.