Isolating Footfall Noise Through Ceilings
There are not many options for soundproofing ceiling impact noise. Whether the structure is of wood or concrete, it requires significant resilience to isolate the intense vibrations from impact footfall noise.
WHAT WILL WORK
In order of highest performing to lowest performing
Treating the issue of impact footfall noise from the ceiling below leaves only resilient sound clips as a viable option of soundproofing a ceiling. For a traditional resilient sound clip approach, we recommend the GenieClips® RST because of the extensive IIC testing for the clip showing exceptional performance at 80 and 100 Hz. The IIC test does not include these two key frequencies, but the frequencies are still important because of the difficulty in isolating low frequencies and the number of complaints regarding low frequency footfall noise transfer. For a slightly different decoupling installation, we recommend the HushFrame Raft, which also has IIC tests for wood structures. View the GenieClip RST or HushFrame Raft.
DAMPING WITH DECOUPLING
Green Glue Compound on a fixed drywall ceiling alone will not help much with isolating impact footfall noise. The intensity of these vibrations is simply too much for any damping compound to handle in a rigid ceiling (drywall screwed directly to framing). However, if the ceiling is resilient, meaning suspended from resilient sound clips or resilient channel, then Green Glue Compound will have significant value in isolating impact footfall noise. This is because damping compounds, like Green Glue Compound, are efficient in resilient assemblies that allow the drywall to flex, thus allowing the Green Glue Compound to shear and work as intended. View Green Glue Compound tubes or Green Glue Compound pails.
WHAT WILL NOT WORK
In no particular order
ADDING A LAYER OF DRYWALL
An additional layer of drywall will do nothing to help isolate impact footfall noise. Resilience is key to foot fall noise reduction so additional mass will not help unless combined with additional resilience, i.e. resilient clips.
RESILIENT CHANNEL/FURRING STRIPS
Resilient channels for soundproofing do have significant benefit when combined with Green Glue Compound. Resilient channel by itself will provide minimal benefit to isolating impact footfall noise. Furring strips provide little resilience with no real benefit in reducing impact noise from above.
Insulation is necessary in sound isolation to avoid resonance issues (basically a drum effect) but provides no benefit in soundproofing ceiling impact noise. This is because the vibrations pass through the joists rather than between the joists.