Understanding Decoupling

Decoupling means mechanically separating the two sides of a wall to make it difficult for vibrations from sound to pass through the wall or ceiling. Here is a simple example of decoupling two sheets of drywall.

And below is a simple sketch of how wood studs couple the conventional wall, and how products like resilient sound clips can decouple it and improve performance.

The stiffness of wood studs couples the two sides of a conventional wall. As a result, sound can easily pass from one side, through the studs, to the other side. Sound can pass through this type of wall without going through the air and the insulation, so insulation has only a limited effect on the single wood stud wall.		By including a resilient decoupling mount, the sound that tries to pass to the other side via the structure is thwarted, and performance can improve. Because sound cannot easily pass through the structure, it has to pass through the air cavity, and insulation becomes far more effective.

• Use as much mass as possible on each side of the wall
  
• Always use double drywall on at least one side of the wall
  
• Use as deep an air space as possible
  
• Use insulation. Fluffy fiberglass insulation is as good as anything out there. The soundproofing insulation may provide a good boost in a standard framed wall, but once your decoupled wall reaches the low 60s in STC the soundproofing insulation impact will be much less noticeable.
  
• Select modern sound clips such as Green Glue Clips, GenieClips, or RSIC-1 clips, over resilient channel (lower resonance point)
  
• Select double stud walls over anything (lowest resonance point.
  
• Utilize viscoelastic damping if possible.
  
• Choose thicker, heavier drywall over thinner – i.e., use all 5/8” drywall if possible

These should be helpful to anybody wondering what the difference is between a standard, staggered, and double stud wall.

Conventional wall (coupled)	Staggered stud wall. Shown is 2x4 studs offset on a 2x6 base plate.	Double stud walls. Two separate rows of studs with drywall only on the outside.

Resilient sound clips are devices that screw to the studs of your wall. Metal furring hat channel is then inserted into the clips, and drywall is screwed into the hat channel. Clips provide decoupling by suspending the drywall on resilient channel about 1.5" from the studs and improve decoupling performance because of the minimal number of connections with clips. The increase in performance by using resilient sound clips (Green Glue Clip, GenieClip, or RSIC-1) is better than the performance of a staggered stud wall with similar construction and equal to the performance of a double stud wall with a 3" gap. Resilient sound clips also provide an affordable alternative to acheive a high rating in a decoupled ceiling without actually setting up inependently framed joists (i.e. room within a room design).