Sound isolation for existing windows - Suggestions?

Hi all. Long time no post! :D We have an office that needs to double as a listening room. It has four sliding windows that face a noisy street. Plus there is construction going on accross the street. Far too noisy for a good listening space. The wall is solid 6" reinforced concrete on the exterior and drywall over 2" wood framing on the interior. So almost all of the noise is certainly coming through the old single pane windows themselves. The major problem is that the building owner doesn't want us to mess with the existing windows. So I'm thinking of semi-permanently installing a 2nd set of sliding windows on the inside frame. Solid sheets of plexiglas or something similar are out of the question because I want to be able to open the windows for fresh air and possible egress in case of a fire. And the secondary windows need to be fairly easy to remove if and when we move out. So is it feasible I install a 2nd window like this? It's my understanding that sliding windows have an exterior flange and are installed from the outside. If so, then I can't simply turn them around because the locking and sliding mechanisms would be inaccessible from the inside. Also I worry about condensation building up between the two windows and rotting the framing. Interior window frame dimensions: 58" x 46.5" x 2" (WxHxD) - 2" depth gives full clearance for existing window to slide. Any suggestions? Thanks! Thomas PS: In the top right hand side of the picture, in the upper right of the window, some of you might recognize Twin Peaks. 8)

I'd go for any normal window (ie. not sliding) including a wooden frame that you just attach to the inside of the existing window frame, do some caulking and additional isolation. Seal it up with wood trimmings and that should be pretty much it. I had the same problem in my studio, so I've been pondering this for a while. In my case I didn't have enough space to fit in another frame on the inside and still be able to open the windows. So I made a frame bigger than the outer frame and just installed it on the inside. Looked pretty silly until I made an intergrated diffusor around the frame and across the wall. a :arrow:

I wouldn't go that route - (Normal window installed inside of) There are companies out there who specialize in sound attenuation windows for city settings - and they work pretty well. If you just stick a standard window in there - you created a 4 leaf system with thin annealed glass - whereas the specialty windows are constructed with thicker laminated glazing. Check your local listings for specialty soundproofing windows - and get some quotes. I have had good luck with these in NYC. Rod

Rod is correct about the laminated glass, I forgot to mention that. I went for a real heavy 28mm laminated glass pane, installed it inside a rubber frame of sorts and then glued it to the wooden frame. Then I just sealed it as one would normally do with a window. This is probably not very cost effective but it sure looks better than any pre-fabricated windows that I found here in Sweden. I guess the window I needed for my construction was not of a standard size so I had to do it this way or get really oversized ones. here's a sketch of what I've done.. best regards and good luck a :arrow:

I have no first hand experience with them, but maybe check these guys out. They make a laminated glass window that goes "over top" of your existing windows. http://soundproofwindows.com/

not sure but are those existing windows actually double glazed? they look like a single glazing... either way, it might be cost effective as well as acoustically ok to just find someone in the SF area to put in a decent heavy single or double (beware per Rod's comments) glazed replacement window built to size/opening/etc so the windows work as expected in terms of opening, seal, etc. Google came up with a number of companies which look like they might fit the bill.