Built in 2001, our modular home has single hung windows, nailed on from the outside. Since there is, in effect, no window structure in the rough opening the most obvious way to replace these windows is to remove the exterior siding, remove the single hung window, and install new double hung quality windows.

Are there any new products available which could make this window replacement project easier, especially eliminating the problem of removing some existing siding? e.g. some type of storm window insert to weatherize these windows?