A retrofit window is the ultimate alternative for replacing your old window. Below are two different frame options for retrofit windows
Flush Fin Frame Window
Sometimes referred to as a flush fin, or z-bar, retrofit windows feature a flange that protrude from the frame, these windows make it easy for you to install without ripping out your older frame window. Typically, a retrofit window is used during an installation replacing aluminum or wood windows.
Retrofit windows are installed by removing old sashes and components of a previous window. Once the old components are removed, the retrofit window is placed from the exterior of your home and fastened into the opening. The frame of the previous window will be intact and covered by the flange of the retrofit window. An proper install will entail a finishing seal and caulk along the outside and a finish with trim on in the inside. The retrofit flange provides a clean look to the exterior and also insulates the interior of the home with proper sealing. Just remember, flush fin windows are installed from the outside, not the inside.
Block Frame Window
An alternative to the retrofit frame is the block frame. Block frame windows are typically used to replace old sash wood windows or block wall applications. Block windows are installed from the inside of a property. When installing and replacing a wood window, sash frames have to be completely removed. The block frame will be set into the remaining previous frame and sill. Sloped Sill Adapters are used to cover the open space cause by the angle of the wood sill on the bottom.