This may not be applicable, but it might be worth a try and i would be interested in what the pro's think. You could change the natural frequency of one glass panel by simply adding mass to it, like a stick on lead weight used in high end car wheels (a flat piece of lead with adhesive on it). If you put one of these on one of the glass panels you would change the natural frequency of that pane. Closer to the middle the better, but a heavier weight near a corner would do the same thing. If a sound guy could measure the natural frequency of a pane, you could actually "tune" the panes to offset the noise transmission. Just a thought.

I have still been doing research (and reading the forum) into my window purchase, and I have some clarifications on the quotes I am currently trying to decide over.... I've decided on the company I plan to use, just trying to decide between quotes from that company. Here are the quotes: (all are from the same company/installer; the only portion that differs between the quotes is the double hung windows) Quote #1 (1) Gorell three lite casement window (2 casements with picture window) w/ Energy Master III triple pane glass (w/ full screens and internal white colonial grids) Picture window U-Value: .22, SHGC .24. Casement windows U-Value: .25, SHGC .18 (5) Mercury Excelum Harmony series Double Hung (triple pane, low e glass, full screens, internal white colonial grids) U-Value: .20, SHGC: .25 (1) MI Window and Doors Model 910 Patio Door (double pane w/ full screens and internal white colonial grids) U-Value .28, SHGC .20 PRICE: $5,055.00 Quote #2 (1) Gorell three lite casement window (2 casements with picture window) w/ Energy Master III triple pane glass (w/ full screens and internal white colonial grids) Picture window U-Value: .22, SHGC .24. Casement windows: U-Value: .25, SHGC .18 (5) Gorell Series 5300 Double hung with double pane AC Master Glass (w/ full screens, internal white colonial grids) U-Value .30, SHGC .25 (1) MI Window and Doors Model 910 Patio Door (double pane w/ full screens and internal white colonial grids) U-Value .28, SHGC .20 PRICE: $5,562.00 Quote #3 (1) Gorell three lite casement window (2 casements with picture window) w/ Energy Master III glass (w/ full screens and internal white colonial grids) Picture window U-Value: .22, SHGC .24. Casement windows U-Value: .25, SHGC .18 (5) Gorell Series 5300 Double hung with Energy Master III triple pane glass (w/ full screens, internal white colonial grids) U-Value .25, SHGC .20 (1) MI Window and Doors Model 910 Patio Door (double pane w/ full screens and internal white colonial grids) U-Value .28, SHGC .20 PRICE: $5,762.00 A few questions: 1. Does anyone have any input/opinion on MI Windows Sliding Patio Door? Their website is: http://www.miwd.com/default.aspx 2. Unfortunately, no one had any input into Mercury Excelum brand of windows.....but the company is on the NFRC list as an approved manufacturer. Does the fact that the manufacturer is on the NFRC list make it a quality window? MI Window is also on the NFRC list. 3. Between Quote 2 and Quote 3, the only difference is upgrading the Gorell 5300 glass package from the double pane package to a triple pane package. Is the improvement in U-Value and SHGC worth the additional $200.00? 4. Installation question. Is there a preference as far as a interior installation vs. exterior installation? Or is it impossible to make that judgment without seeing the house/window? Thank you for your help. mm

The proper way would be to measure the new windows to fit inside the existing frame. Sounds like you already ordered them to replace the whole frame though. Theres no way of getting around it you'll need to use the flange. If you have casings around the windows or vinyl siding it will be a pretty easy job.

which softlite model?... Quite a discrepancy from the bottom to the top of their lineup imo.