A triple leaf partition has two air cavities rather than the typical one air cavity. Similarly, a quadruple leaf partition has three air cavities. Triple and quadruple leafs are most often created when constructing a new wall in front of an existing wall. The other common ways include installing Hush isolation sound clips or resilient channel over existing drywall. This applies to both walls and ceilings alike. A leaf in a partition is a solid layer, like drywall or plywood…
The drawings above show single leaf (no air cavity), double leaf (like most assemblies), triple leaf, and quadruple leaf assemblies, both clipped and standard framing. It is necessary to remember that two layers of drywall directly against each other still only count as one leaf because there is no air cavity between the layers. In the sketch below we show again double through quadruple leaf walls, but this time they all have the same number of drywall layers.
It is not illogical to presume that the quadruple leaf wall on the far right would have the best sound isolation. After all, the sound has to go through drywall, air space, drywall, air space, drywall, air space, and then again drywall, often with insulation within each air space. In a double leaf wall, the sound has to make it through only one air space. While it makes sense that the quadruple or triple leaf assemblies are better than double leaf assemblies, it is, unfortunately, not the case.
Testing For Common Walls With Multiple Leafs
The STC values shown above for the common framing assemblies are from a series of tests commissioned by Owens Corning and Sound isolation clips. While STC does not tell the entire story, it is clear that the triple leaf and quadruple leaf assemblies should be avoided whenever possible.
Testing For Clipped Assemblies With Multiple Leafs
The STC values shown above for the Sound Isolation Clip assemblies are the results of independent tests. The performance loss created by the retrofit clip installation was significant, but lessened by insulating the space between the existing drywall and new drywall with an R-8 insulation. The retrofit performance would have been much lower without the extra insulation.
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you never really do define what the triple leaf effect is in this article, you just define what triple leaf is.
Hi there,
we are trying to soundproof our basement ceiling from living room upstairs. This is what the builder came up with:
“The drywaller has recommended a layer of Donna Conna (a sound proofing board), then resilient board and then the layer of 5/8″ drywall.” They meant resilient channel, not resilient board. There will also be Safe ‘ n ‘ Sound batts to fill the cavities between floor joists.
Just wanted to ask if we could be creating a triple leaf effect? I don’t understand it very well.
Hello Alex,
Of course the best way to stop the noise is at the source IE: impact, footsteps would require underlayment in living room. Voices transferring from below can be addressed from below. Full isolation addressed from the ceiling below and the most recommended installation and would require a full renovation including removal of existing drywall, adding an acoustic rated insulation, installing a rubber isolation clip and track system to the studs and installation of 2 layers of 5/8” drywall with Green Glue Damping Compound between the layers. Putty Pads are installed behind electrical outlets. This Assembly in airborne sound transfer will provide approximately a 75-90% reduction by decoupling the drywall from the structure. As for Impact approximately 30 -50%. To improve impact to approximately be 50-60%, line the underside of the sub-floor layering Green Glue Compound and double 5/8 drywall. The success of the soundproofing is in the whole assembly and the installation.
If I fill the joists with rockwool, then cover ceiling bottom with MLV then install iso clips then sonopan and 5/8″ drywall. Will this be very effective? There would only be one air gap with is where the isoclips sit, so I would be avoiding the triple leaf, yes?
Is this the best option?