Our 1998 windows were single-pane in some rooms and basic double-pane in others. Evening traffic on the nearby arterial is steady from 4:30 to 6:30. I used that window every day for three weeks.
I tested three options installed in the same opening over successive periods so the outdoor sound source stayed consistent. Measurements were taken with a calibrated phone app cross-checked against a standalone meter, always at the same interior spot five feet from the glass, windows closed, HVAC off.
The three windows
Low price: builder-grade double-pane vinyl, roughly $350–400 installed per average opening.
Mid price: better double-pane with improved interlock and slightly thicker glass, around $650–750.
High price: triple-pane with laminated glass on the interior lite, roughly $1,100–1,300.
All were replacement units sized for the existing opening. I recorded A-weighted decibels during peak traffic and during quieter late-evening periods for baseline.
Results
Original windows: peak traffic averaged 58–62 dB inside. Late evening dropped to 38–42 dB.
Builder-grade double-pane: peak traffic 51–54 dB. Improvement of roughly 7–8 dB. Noticeable but still clearly traffic.
Mid-range double-pane: peak traffic 46–49 dB. Another 5 dB better than the cheap unit. Conversation level inside became comfortable without raising voices.
Triple-pane laminated: peak traffic 42–45 dB. Best absolute numbers. The difference from the mid-range was real but smaller than the jump from original to mid-range.
Subjectively, the mid-range unit removed the sharp tire and engine edges. The triple-pane softened the remaining low-frequency rumble further. For sleep and for Mia’s nap times, both the mid and high options were acceptable. The builder-grade still let enough through that we noticed every truck.
Other performance notes
I also checked for obvious air leakage with a simple incense stick on a windy day. The builder-grade unit showed more movement at the interlocks. The mid and high units were tighter. U-factor differences were as expected: the triple-pane was the best thermally, the mid-range close enough that our summer electric bill impact will likely be similar once the whole house is done.
UV transmission was lowest on the laminated triple-pane, which matters for the sofa and for skin time near the glass. The mid-range had a decent low-E coating that still blocked a useful amount.
Cost versus benefit in this house
The largest single improvement in daily comfort came from leaving the original single-pane era and moving to a competent double-pane. The further step to triple-pane laminated bought measurable extra quiet and better UV control, but the dollars per decibel were higher.
For rooms that face the street and are used for sleep or focused work, the mid-range or better is worth it. For side elevations with less traffic exposure, the performance gap narrows and the cheaper unit becomes more rational.
I care about the number on the meter at 5 p.m., not the brochure claim. In Austin traffic, the mid-price window delivered most of the practical quiet we needed. The expensive one delivered the rest, plus better long-term UV protection for everything near the glass.
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