Before you start shopping for replacement windows you need to know the difference and benefits between a replacement window and actually replacing the entire window.
For those of us in the window industry the term replacement window is given to what is usually a vinyl window that is placed into an existing window frame. Meaning that the old wood sashes and stops holding them in are removed and the new vinyl pocket replacement window is slid into the old wood frame pocket. This type of window replacement has its drawbacks.
The very first thing to consider if contemplating the use of a pocket replacement window is the condition of the existing wood frame. Most people want to replace windows because the old wood is deteriorated and rotted. Check the wood at the sill or bottom exterior, probe it with a small screwdriver to see if it soft. If you can easily penetrate any part of the sill you may need to consider removing and replacing the entire window.
The next consideration is the opening around the current window. One of the main advantages of using a pocket replacement window is an installation without damage to the existing interior trim surrounding the existing window. However you should make sure the opening around the existing window is properly insulated. The air you feel coming into your home could be infiltrating through the void between the window and the rough opening. Putting a new energy efficient window into an existing un-insulated frame is not going to help reduce energy costs greatly. So you may need to remove some of your window trim and check the opening for insulation.
Esthetics is another factor when using a pocket replacement window. Remember this type of window is fitted into the current frame. So you are now creating another void that needs insulated and this also poses another potential air infiltration risk. You will also reduce the amount of visible glass by putting another window frame inside an existing window frame. The exterior esthetics of your home can be dramatically altered by the presence of two window frames. Picture the current glass you look through now reduced by four to six inches. And the change in looks it will have on the exterior of your home.
Code requirements are yet another, but very important factor to check before you purchase any window, be it a new one or a replacement. Since a pocket replacement window is smaller than the existing window so too is the sash opening. The sash opening has certain egress code requirements so that rescue personnel can gain access to your home in emergencies. These egress codes differ throughout the country and are usually around 5.7 square feet with minimum width and height restrictions. These egress codes are typically focused mainly on bedrooms. Most window manufactures can provide you with the egress information on all of their products. Be sure to check your local code requirements before installing a window that may not meet code.
There are many factors surrounding your decision to replace your windows. It may be more advantageous to remove and replace the entire window rather than installing another window into a rotted leaking opening.