Windows can be a weak spot in the overall process of soundproofing a room. If you have already soundproofed a room, it is very common to discover that there is still some significant noise leakage coming from you exterior windows.
Regular windows are simply not designed with maximum soundproofing in mind. Many times there are small gaps in the frame where noise can leak through.
They might also lack the thick triple glassed panes found in specialized soundproof windows.
Imagine trying to work in a downtown New York office. Without soundproof windows, much of that street noise can leak into the office space, sacrificing productivity and peace of mind.
What Makes Soundproof Windows Different?
Thicker Glass – Soundproof windows are typically constructed with thick panes of laminated glass, sometimes up to ¾” thick. In general, thicker glass has better soundproofing performance. Additionally, window makers sometimes add a layer of PVB plastic sandwiched between panes to dampen vibration. An inert gas such as argon or krypton is then injected into the small space between the panes. The layer of gas creates a buffer to further dampen incoming sound.
Special Frames – Soundproof windows are commonly used as an add-on to existing window systems. One advantage to this configuration is that no new structural modifications or repairs are required to install the soundproof systems. The windows are specially designed with frames that attach to track mounting systems.
This provides continued access to the existing window, and allows for temporary removal as needed. Soundproof windows also feature spring loaded frames or mounting spacers. The springs apply pressure to the existing window frame, creating a seal. This reduces vibrations, draft, and creates a dead zone of air that enhances sound dampening.
An alternative to expensive windows is soundproof window inserts. These are basically “window plugs” that fit tightly into a window frame to seal off any pathways that noise can travel through.
Window inserts are cheaper than replacing existing windows, and can look just as good.
STC Ratings Explained
Sound Transmission Class (STC) is simply a rating of how effective something like a wall, ceiling, window, or door is at dampening sound and noise. It is an established rating based on ASTM and ISO standards.
See the ASTM Classification E413 and E90, and ISO – 140 Specification for more details.
The STC ratings of soundproof windows are varied because each installation is different, meaning manufactures will only provide an STC range for their products. The table below lists some typical values
||Typical STC Range
|Glass: Single Paned||25-28|
|Glass: Dual Paned||26-34|
|Soundproof Window + Existing Single Pane||42-49|
|Soundproof Window + Existing Dual Pane||45-54|
Factors like existing window thickness and amount of air between existing and soundproof windows are a few of the variables in the rating. Thicker glass and more air gap will generally provide higher STC ratings.
While soundproof windows cannot reduce the incoming noise to zero (physically not possible), they can reduce noise in significant amounts, resulting in excellent sound blocking when STC ratings of 40 and above are achieved. Depending on your situation, they may very well be an excellent investment.
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