Reducing Exterior Noise
How to reduce noise from outside is an exceedingly common noise issue, especially for those living in high population areas. Several products and wall assemblies will help with exterior noise reduction. However, without addressing the weakest points, the wall will be one expensive, and still pretty noisy, exterior wall.
A typical exterior wall consists of a layer of drywall, 2×4 framing, R-13 insulation, a layer of OSB sheathing, and either siding, stucco, or brick with the occasional window or door. The STC rating of your exterior wall will vary somewhere between STC 35 to 45 depending on the exterior finish with an OITC rating of approximately 35.
DEAL WITH THE WEAKEST LINKS
If your exterior wall has a door or window, then this is the best place to start. Doors and windows are typically in the STC 20-30 range, much too low when compared to the average exterior wall. Assuming the door or window is small in comparison to the size of the wall, it can rate within 10 STC points of the wall without significantly affecting the overall STC rating of the wall.
If your wall has both a window and a door, then the window should be treated first since it is likely the weakest of the two. Replacing your windows with ’soundproof’ windows will help performance. To replace an exterior window, first remove the perimeter of the window frame. If the exterior is rock, brick, or stucco, then replacing the window could turn into a significant project. Replacing your windows with a high STC rated window will provide the cleanest look, as well as pretty good results from a single window.
However, this construction headache can be avoided by adding a second window to the inside of your window frame. The STC rating of the opening improves to at least the mid 40’s STC with the addition of the second double pane laminated window. A dramatic improvement achieved with minimal construction.
At that point, your windows will perform better than the average exterior wall. There are several companies that sell windows that can be used for retrofitting on the interior side of your windows frame. Run a search to find a company that sells retrofit windows.
Watch the video below to see the effect of adding a second window to your window installation.
FINISH THE WALL
As mentioned before, an exterior wall STC rating is likely somewhere in the mid 30’s to mid 40’s. With minimal demolition, the most basic way to improve exterior walls is by adding a layer of 5/8″ drywall with Green Glue Compound in between the layers. The Compound with an additional layer of drywall will bring the STC rating up to the low to mid 50’s. Exterior soundproofing will also improve. The performance of the wall after applying the Compound will exceed the rating of the new window. Without major investment into the project, this is likely as good as it will get. View Green Glue Compound tubes or Green Glue Compound pails.
To us, the best bang for the buck is a second window added to the existing window frame with Green Glue Compound and an additional layer of drywall added to the existing drywall. If your wall does not have any windows or doors installed, consider upgrading your wall using either a double stud framing technique or resilient sound clips like the GenieClip® RST. The added performance of GenieClips® RST over Green Glue Compound in a wall without windows or doors is immense for all frequencies.