Why is a replacement sash better than replacing a full frame window?

Q. Why is a replacement sash insert window better than replacing with a standard, full frame window?

These Biltbest replacement sash units fit your existing frame - not to mention they are installed without disturbing any interior trim or exterior trim or siding on your home. Full frame replacement windows are appropriate when the entire window needs replacement—for example, when it's substantially out of square or has deteriorated beyond any possible repair. The window, including sash, frame and casing is replaced.