Interior Noise

Unwanted music from a stereo system. Loud noises from a home theater. A noisy washing machine. We all have it in our homes, but we often fail to account for it when planning new construction or consider it in renovation projects.

While in the planning stages of any construction project, work to build noiseproofing solutions into your specifications. Your architect or general contract can assist with this. If you need advanced assistance, visit our distributor listings to find an acoustic specialist to work with.

Renovating may present more challenges than new construction, but Green Glue Noiseproofing Compound works perfectly to simply add on top of existing structures. Apply Green Glue Noiseproofing Compound and an additional layer of drywall to the existing ceiling if airborne noise, not impact noise, is the primary concern.

WALLS

When it comes to noiseproofing walls, first decide whether to work with the existing walls (non-destructive upgrading), or to tear out existing walls (destructive upgrading). Destructive upgrading is more effective, but it costs more and requires more time.

Here are some wall noiseproofing tips:

• Remove direct air paths between rooms by sealing cracks covered by wall trip, unsealed doors, and pathways that involve the ventilation system.
• Add an extra layer of drywall with Green Glue Noiseproofing Compound. Just adding a drywall layer alone may only improves a wall’s STC rating by 2 points. But when Green Glue Noiseproofing Compound is added with the additional mass, the performance dramatically improves — as much as 12 STC points with a single additional layer of drywall, and 16 STC points for a double layer. Note: Avoid using lightweight drywall as mass will typically help with sound reduction.

CEILINGS/FLOORS

When feasible, add insulation during a renovation project:

• Blow flexible insulation into the ceiling cavities, filling them, if they aren’t already insulated.
• If ceilings can be removed, you have a good shot at reducing most of the noise from the floor above. 

Next, upgrade the ceiling with Green Glue products and other materials using one of these methods:

• For the most effective sound isolation, separate ceiling joists and wall studs with double drywall and Green Glue Noiseproofing Compound.
• Use sound clips like Green Glue Noiseproofing Clips or spring ceiling hangers with double drywall and Green Glue Noiseproofing Compound; or clips or staggered studs with Green Glue Noiseproofing Compound on the walls.
• Install a resilient channel and Green Glue Noiseproofing Compound with double drywall on the ceiling, and furring or directly-screwed drywall with Compound on walls.
• Green Glue Noiseproofing Compound and double drywall screwed directly to the joists and studs.
• Avoid using lightweight drywall as mass will typically help with sound reduction.
• Note: Do not use sound clips, resilient channel or spring ceiling hangers over existing drywall as this creates a triple leaf effect.

UNDERSTANDING THE TRIPLE LEAF EFFECT

In its simplest form, a triple leaf wall is a wall with TWO air cavities, not just one as in a typical wall. (In case you’re curious, a quadruple leaf wall would be a wall with 3 air cavities).

Why is a triple leaf wall a bad thing? After all, it would seem to make sense that any wall structure that has more air cavities for the noise vibration to cross would be more effective at reducing sound transmission. Unfortunately this is not the case.

The reason lies in the science of resonance. Decoupling isn’t effective at all frequencies. If you take two layers of drywall, and separate them with an air space, it doesn’t necessarily improve things at low frequencies. For example, the deep bass from your neighbors subwoofer might pass easily even through decoupled walls. The air in the cavity creates a continuation of the vibration, called resonance. To attain good low frequency performance, this resonance must be as low in frequency as possible, however for any given mass and space, a triple leaf wall will always have a higher resonance point than a standard double leaf (single cavity) wall. More information on Triple Leaf Effect is available here.

INSULATION

Many homeowners think that simply adding insulation will improve noiseproofing. While insulation is important, you may find that insulation alone will not provide enough sound isolation between rooms. Insulation often provides significant noise reduction unless the noise is structure-borne or flanking noise is present. If insulation is not added to the cavity, the compound is not expected to perform as well.

Here are some tips:

• If you have conventional walls or ceilints, structure-borne vibrations and sounds pass easily from one side of the wall to the other, and insulation does little to help.
• Insulation works best if your walls are decoupled, i.e., there are no mechanical connections between the two sides of the wall.
• Don’t be tempted to use dense insulation thinking it will work better at isolating sound. It can be more expensive and actually raises the resonance of low frequencies.
• Bottom line: insulation alone will not get rid of noise, but the inclusion of insulation in a cavity can have a tremendous impact when coupled with Green Glue Noiseproofing Compound.