A common situation for our customers is excessive noise entering their homes from outside. Exterior noise sources abound, with the most common being aircraft and traffic. The first important issue of dealing with exterior noise stems from these common noise sources - both are rich in low frequency noise. So, when attempting to reduce exterior noise, low frequency noise will have to be considered.
The second component of the overall situation that affects exterior noise is the presence of windows and doors. At some frequencies, the windows and doors will let more noise in than the walls. And this is important, because the barrier between you and the noise outside is only as good as its weakest link.
In other words, you can beef up your walls all you want, but if your windows are 1970's aluminum single pane windows then your efforts to isolate sound will not be significant.A heavy exterior door will rate higher in low frequencies than a standard framed wall, but considerably worse in high frequencies than a standard framed wall. Because, except in situations where extremely high performance doors and windows are utilized, the walls are not the limiting factor at high frequencies, the best upgrade you could make to the walls would focus on low frequency noise.
Unless you intend to do some major renovations with significant improvements to the windows and doors, just adding a either layer of Green Glue Compound and some drywall or replacing the current drywall and setting up a resilient sound clip system will get you almost all of the way to the best performance you can attain and a very good level of performance it is.
For the upgrading of existing constructions, or for constructions where many thousands of dollars are not available for exotic windows and doors, much can still be done. For these applications, it is important to put your money where the most improvement can be had. In the table below we show calculations of the performance of various improvements to this overall assembly, and the net final result.
Performance of Adding Different Types of Soundproofing Materials
| Wall Upgrade | Floor Space Lost | Wall STC | Wall OITC |
| As-is, standard exterior wall | --- | 37 | 29 |
| Add one layer of 5/8" drywall with Green Glue Compound in between | 5/8" | 52 | 35 |
| Remove existing drywall, add resilient sound clips with hat channel and 2 layers of 5/8" drywall | ~2 1/4" | ~62 | ~42 |
| Remove existing drywall, build new stud row 2" from existing studs, add 3/4" OSB to the outside wall, add 2 layers of 5/8" drywall to the inside wall, add one more layer of R-13 insulation in newly framed wall | 5 1/4" | 67 | 59 |
The above STC Ratings represent high frequencies while OITC Ratings represent low frequencies.
