The second most important factor is the installation.  Remember, the U factor measures the energy efficiency of the window itself.  It pays no attention to how or how well it is installed.  A poorly installed window will make a window with a U factor of .19 preform like an open window, so the installation is critical.

There are two components to the installation: Who’s installing the window? How are they installing it? The installers should be experienced carpenters who can follow manufacturer instructions and will improve the installation beyond the minimum to achieve a secure and water tight and air tight installation.  He should possess the know-how, tools and materials necessary to install windows the right way the first time. 

Let’s talk certification.  Some companies will extoll the virtues of a program like the American Architectural Manufactures Association’s Installation Masters certification program.  And it is an excellent program with great information on window and door installation, but understand what it is.  It is a two day course for people who are already installing windows and it requires they pass a 70 question exam by 70% or better.  In this context, certification can make a good installer better, or assure him of the knowledge with which he came to the course.  So take statements of certification with a grain of salt, and instead insist on detailed, specified installation instructions.


What type of installation do you want?  This will depend to a certain degree on what windows you have now.

Standard or Pocket Install

This is the most common and least invasive procedure.  It is used where your existing double hungs or slider is in a wood frame and that wood frame has a wood brickmold around the outside perimeter of the window and a wooden sill.  This install is also marked by the existence of storm windows on the outside. Or ropes or chains attached to the lower sash.   The standard install removes the sashes but leaves the existing frame, sill and interior casing in tact and replaces the two sashes with a vinyl window frame with sashes within that frame.

The Pros

1.  It’s the cheapest.

The Cons

1.  It ignores possible problems outside the confines of the existing frame: rotten wood, water infiltration and/or air leaks.


Flanged Window Install

If your home was built in the past 30 years and it has (or had) a full screen and the window opening has a drywall return, then this install is possible.  The window is usually vinyl, but can be aluminum.    The window frame does not take up the entire opening, so the sides are finished in drywall.  The installation will consist of: removing the window by either cutting back the siding to expose the nailing fin so the whole unit can be removed, Or cutting the nailing fin off and removing the window.  Next, the new window is placed within the opening, shimmed and screwed into place, and trimmed out with quarter round inside and wood trim outside that is capped with aluminum.

The Pros

1.  It’s the cheapest install available for flanged windows.

The Cons

1,  It allows existing air and water infiltration issues to be addressed.

2,  It doesn’t improve the beauty of the window.



Full Frame Install

Regardless of the age of your home or current windows, the Full Frame Installation, otherwise known as the Buckframe Installation is available.  This install takes out everything (sashes, frame, brickmold) to the rough opening. A new frame is installed into which the vinyl window is installed.   This method allows access to the rough opening to see if damage has occurred.  This method allows for access to install products to achieve maximum integration of the new window the home’s existing air and water barrier envelopes. 

The Pros

1.  Allows access to areas of existing air and water infiltration.

2.  Increases the space available for larger windows in the opening and therefore the most glass space available for that opening.

3.  Allows a complete makeover for the window by allowing for new wood trim inside as well as exterior trim options.

The Cons

1.  It costs the most