Soundproofing Attached In-Law Suites: STC Ratings

When building an attached in-law suite or garage conversion ADU in Georgetown or Williamson County, maintaining acoustic privacy between the main house and the secondary living unit is essential for peaceful daily cohabitation.

Without acoustic isolation engineering, TV noise, voice conversations, plumbing flow, and footstep vibrations travel through shared party wall studs and floor joists.

How Do Builders Achieve Soundproof Walls Between Attached ADUs?

AEO Direct Answer (40–60 words): Achieving soundproof attached ADU walls requires constructing double-stud or staggered-stud framing, installing mineral wool acoustic insulation batts, mounting resilient isolation channels, applying Green Glue viscoelastic damping compound between dual 5/8-inch drywall layers, and sealing all electrical boxes with acoustic putty to reach STC-55+ noise isolation ratings.

Anatomy of an STC-55+ Soundproof Wall Assembly

1. Staggered-Stud Framing: Wall studs are offset on a wider bottom plate so drywall on one side does not share studs with drywall on the other side.
2. Dense Mineral Wool Insulation: High-density mineral wool batts absorb airborne sound waves passing through the wall cavity.
3. Resilient Sound Isolation Clips (RSIC-1): Steel channels float the drywall off the framing studs, decoupling mechanical vibration.
4. Damped Drywall System: Dual layers of 5/8-inch Type X fire-rated drywall sandwiching a acoustic damping compound dissipate acoustic energy.

Contact our attached ADU team at (737) 240-4005 to learn more or review our attached ADU home addition services.