Flash & Batt
STC stands for Sound Transmission Class, and it is a rating system used to quantify the sound insulation properties of building materials and structures. The STC rating measures how well a construction element, such as walls, floors, or windows, can reduce the transmission of airborne sound from one side to the other.
STC ratings are commonly used in the construction industry to help design and select materials that provide effective soundproofing for residential, commercial, and industrial buildings. The STC rating is based on a standardized laboratory test that involves exposing a partition to a range of frequencies and measuring the sound transmission loss at each frequency. The higher the STC rating, the better the material or construction element is at blocking the transmission of sound.
Here is a general interpretation of STC ratings:
- 25-30: Poor sound insulation; normal speech can be easily understood.
- 30-40: Fair sound insulation; some reduction in speech intelligibility.
- 40-50: Good sound insulation; significant reduction in speech intelligibility.
- 50 and above: Excellent sound insulation; speech is difficult to hear and understand.
Sound absorption refers to the process by which sound energy is absorbed by a material rather than being reflected or transmitted. When sound waves encounter a surface, some of the sound energy is absorbed by the material, reducing the sound’s intensity and preventing it from bouncing back into the environment.
Materials with good sound absorption properties are often used in spaces where it is desirable to control or reduce the level of noise in your home or office. Common materials used for sound absorption include acoustic foam, fiberglass panels, rock wool, fabric-covered panels, and perforated metal panels.
The effectiveness of sound absorption is typically measured by the Noise Reduction Coefficient (NRC), which ranges from 0 to 1. A higher NRC indicates better sound absorption. Different materials and surfaces have varying degrees of sound absorption depending on their composition, density, and structure. Properly designed acoustic treatments can help create a more comfortable and controlled acoustic environment by managing reverberation and reducing unwanted noise.
Walls – R11/R19 fiberglass batt (depending on wall thickness)
Floor/Ceiling – Fiberglass batts better for sound proofing from below, above floor joists below floor. For instance, batts can be laid on top of suspended ceiling to keep noise from moving room to room.
Rockwool Thermafiber batts, SAFB (sound and fire mineral wool batt) are better for floor joists
Open cell spray foam, better to block sound from above.
We would normally use sprayfoam if trying to reduce sound transferring from the floor above a space. Applying foam to the underside of the floor decking can reduce sound before getting into the floor cavity.
Of course to achieve maximum sound reduction these products can all be used together.