Windows and doors need replacement at some point in their lifecycle due to structural failure (cracks, dings, corrosion), to replace with newer, energy-efficient models or due to aesthetics (remodeling). Another benefit according to the National Association of Realtors is that property owners can recoup 73 to 77% of the costs of replacement windows upon resale.
Methods of retrofitting may change due to the framing materials but typically the sashes (the frame holding the pane of glass) and jambs (the vertical portion of the structure onto which the door or window is secured) as well as the molding to expose the old frame. The frame dimensions are documented allowing the new window or door to fit easily into the existing space. The main difference between this and new construction which strips everything down to the studs is time and money.
When windows or doors are retrofit into the existing framework, the company doing it must be familiar with the city, county and state regulations regarding their replacement. Knowing the laws and regulations regarding the construction is of the utmost importance. It is not just about exchanging one window or door for another. The codes specify the testing that must be done for durability, sustainability, maintenance, fenestration, and noise and energy ratings of the replacement product. All these elements work together to provide property owners with retrofit windows or doors that not only fulfill their vision but meet all the requirements (permits, code, etc.) that the city, county, and state have specified. Building codes cover everything from the height and width of an exit door to the recommended size of window openings and the supports used for windows and doors.
Metal window frames have an exterior flange (about two inches around) which conceals the frame on the outside of your home. Interior trim is used to cover any differences in the interior of the house or multi-residential unit.
The process is a little different with wood framing. To start with it requires a retrofit window with a sill that has the same slope of the original window sill. The windows are entirely removed, leaving the perimeter frame in place.