I have been suffering from writer’s block this week and am struggling to develop an engaging discussion topic.
This morning, I reviewed customer feedback through Avid Ratings and realized some negative comments regarding soundproofing in some of our recent new builds. I thought it would be a good idea to identify some of the challenges and limitations of soundproofing in a wood frame home, particularly between floors with surface finishes, such as hardwood, that we face. In the end, as with all things, the budget limits what we can do, and while there is always a better solution, the budget often does not allow for superior assembly.
While you can mitigate sound in a wood-frame home, high Sound Transmission Class (STC) ratings can get expensive. Single-family homes are not required to achieve any particular level of soundproofing, so in lower-cost homes, you might find little or no soundproofing at all.
To essentially muffle sound from room to room or floor to floor, we would use sound insulation such as Owens Corning’s Sound Attenuation Batts. As mentioned above, this deadens sound to a degree and can improve STC class ratings by about 4-10 dBs.
(This is the level we typically do in our budget-based homes). The sound batts can be combined with additional layers of drywall. As an additional strategy specialty products such as Certainteed’s QuietRock drywall can be used. The QuietRock application can increase the wall’s sound performance by up to 13 dBs. Additionally, the drywall can be separated from the framing with a metal channel to help reduce sound vibration transmission. The addition of extra drywall, metal channel and QuietRock will begin to incur significant additional costs. (we would not typically use QuietRock unless the client requested it, as it comes at a premium price) This can be applied to walls and floors with similar improvements. Remember that eliminating sound transmission through a wood-framed floor with hard surface flooring is challenging without extreme measures.
If you want to eliminate sound between walls, build a 2-wall assembly separated by an air space. Better yet, separate the floor sheeting with a saw cut (if your engineer will allow it). This prevents the sound vibrations from transmitting through the wood framing. Combine the double wall with sound batts, QuietRock, and Green Glue between the drywall and metal channel, and you begin to really eliminate sound transmission. If practical, preventing air movement between the rooms will also significantly reduce noise transfer – use air-tight electrical boxes and ensure outlets are not installed back to back. Sealing one wall with spray foam insulation will air-seal one room from another and reduce sound transmission.
Floors like the ones above are more difficult. The above strategies, combined with a 1.5″ concrete topping, are the best you can do without framing a secondary ceiling separate from the floor framing. As you can imagine, the cost starts to go up exponentially.
Even with sound batts, QuietRock, Green Glue, metal channels, and concrete topping, the sound will still transmit from floor to floor. Additionally, open stairwells and air gaps below doors make it difficult for a wood-frame home to eliminate sound transmission.
If soundproofing is a high-priority expectation for your new build or renovation, highlight this in the early design meetings so your design team and builder can incorporate it into the build. Concrete topping and double stud walls cannot be easily added once construction has begun.
As mentioned above, the strategies come with additional costs and, if added during construction, will most likely not fit within the original budgets.
If you want to learn more about building soundproof homes, call us.
Cheers,
Bob Deeks
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