Basically there is a restriction on getting new windows as the type in unusual that are currently there and management company would not allow new windows. So basically putting another set of windows internally should cut out sound. Anyone do this ? Any recomandations and prices. Two large front windows is what would need doing. Primary reason is to cut out sound from the street such as traffic and drunks. There is sufficient room in the window surround for a gap of up to 8 inches between both sets.