How to Soundproof Ceilings with STC Ratings

Sound transmission class is used to rate soundproofing.

Sound transmission class (STC) is the rating system used for soundproofing. An uninsulated wall or ceiling has a 20 to 25 STC rating, which allows speech to be heard outside of the room. Metal joists have a higher STC rating than wood joists. Applying three layers of acoustic batting between the joists will increase the STC. Installing sound channels between the two layers of drywall will increase the STC rating. Sound channels are similar to strapping, but are made of metal. Sound channels create an air space where noise will be absorbed. The combination of the acoustic batting and the sound channels mounted between the two layers of 1/2-inch drywall creates an STC rating of 52, which is excellent.

Things You'll Need

• Measuring tape
• Acoustic batting
• Insulation support wires
• Screws
• Drill
• 1/2-inch drywall
• Sound channels
• Acoustic tiles (optional)

Instructions

1. Measure the area to figure the amount of materials needed to cover the square footage of the room. Measure between the joists for the width of acoustic batting needed. Acoustic batting comes in 14-1/2 inches or 22-1/2 inches wide and is 3-1/2 inches thick. Purchase 20 percent more materials than needed, to allow for waste.

2. Cut the acoustic batting to the length needed to go from wall to wall between the ceiling joists. Push the acoustic batting between the ceiling joists, using insulation support wires to hold the batting in place.

3. Screw the first layer of 1/2-inch drywall to the ceiling joists. Screw sound channels every 16 inches in the opposite direction of the ceiling joists, or install acoustic tiles over the 1/2-inch drywall.

References

• Handy American: Soundproofing
• Home Tips: Soundproofing Walls & Ceilings