We will be replacing a bunch of windows soon as part of our downstairs remodel. We live on a busy street and we noticed a *HUGE* sound reduction when we remodeled the upstairs by switching from 1/8" x 1/8" thick double pane sliders to 1/8" x 1/4" double pane casement windows. They were custom made Milgard windows through a specialized local window installer- pretty expensive.

For the downstairs we will be re-building most of the walls (it is a "sun room" now) so we will be able to ensure the window sizes conform to readily available off the shelf sizes. Are there any brands available at the usual big box stores that offer double pane 1/8" x 1/4" thick glass windows in any format? Doesn't have to be casement- but my theory is that casement leaves less seams for noise pollution

 

"Off the shelf" means the retailer made a judgment call on sizes they thought would be "standard". In reality no window is made until you order it, just like the retailer did. It is convenient to have openings that allow windows to fit, and you certainly have an advantage in building your own openings. They may not be available in California, but I have had very good luck with YKK casement windows (yes the zipper people). Milgard makes a good window, as do Jeld Wen, Andersen and other higher end manufacturers.

 

This information may be useful: Best Soundproof Windows | Replacement Windows Reviews

 

You might also research hurricane or wind resistant windows. Here in NC they are used in houses at the coast to resist high winds and not let flying debris break through. They are also burglar resistant because they are quite difficult to penetrate. I have noticed that they block sound more than traditional double pane windows.

 

As you probably know, a double pane unit that uses 2 different thicknesses of glass for each side of the unit will generally have a better STC rating than one with the same thickness glass. I don't know of any windows that come standard that way, but you can compare the STC ratings to know which window is better than another.

 

Thanks all for the tips- sounds like we may have to order them. We will definitely want offset thicknesses. And I like the tip about the impact resistant, or hurricane windows- since these would be at street level.