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Author Topic: 1x interior w/ big air gap or 2x w/ 2 smaller gaps  (Read 962 times)


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1x interior w/ big air gap or 2x w/ 2 smaller gaps
« on: December 19, 2019, 10:20:59 PM »


I've been reading the forums and researching how to reduce some sound noise. These are great forums. Thank you!

50-60 dB road noise I would like to reduce. It is coming through walls and windows. I've been told the walls were built w/ double 2x4 framing off-set so there is *no contact* between the outer frame and the inner. I assume therefore most noise comes through the windows.

Windows are double pane window vinyl frame, 8" deep sill, and 96" x 36".

Any suggestions how to reduce the noise will be much appreciated. I was going to start with a DIY acrylic sheet in the frame, sealed around the edges with caulk.

I know mass and air gap are key, and mass is often given up because of the benefits of acrylic. What type of air gap is best? I see from,3267.msg8475.html#msg8475 that a 1" air get has STC 37 and 2" has STC 43 for the same windows on either side.

Given my 8" frame, and I want to keep a small frame when project done, which is better:

existing double pane, 5.5" air gap, 1/2" acrylic, 2 inch sill OR
existing double pane, 2" air gap, 1/2" acrylic, 2" air gap, 1/2" acrylic, 2 inch sill.

Or would 1/4 + 1/2 be better than 1/2 + 1/2 to break harmonics?
Other suggestions?