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What you need to know before purchasing replacement windows

A fine example of a window bay

A fine example of a window bay


Deciding to purchase replacement windows for your home is a big deal. The cost can be quite high depending on what style and type of window you choose. So knowing the correct questions to ask is not only important, but essential for the wallet.

The purpose of this hub is to provide the knowledge you need to ask informed questions and hopefully derail the unscrupulous salesman or contractor. All references to pricing will pertain to windows with one operating sash known as single hung windows. Pricing for other styles such as double hungs or casement style windows are slightly higher.



The last 17 years of my professional life have been spent in the building product industry with an emphasis on windows and glazing. I've worked in production, distribution, service, management, ownership and sales. I've seen a lot of things and heard a lot of stories.

Most of my experience has been in new construction but I've also done a fair amount of replacement projects. Each job is usually a bit different and rewarding. Even so, the industry can also be dangerous; (in the sense that the less you know, the more apt you'll pay more than you should). - The following is a general breakdown on what you should know before allowing anyone to sell you replacement windows. My intent is to keep you out of the dark.


Some replacement windows are priced by a call out size. For example, a 3' wide by 5' tall window would be "called out" as a 3050, (a 3' 0" width by a 5' 0" height).

The majority of replacements however are sized and priced by the united inch (UI); which is the sum of the window's width + height in inches. For example, if you have a standard window measuring 36" wide by 60" tall, the UI is 36 + 60 = 96 UI.

Most windows priced by the UI are done in ranges; usually 1-50 UI, then 51-100 UI, then 100-150 UI, and so on. So ask this question first. How are my windows being priced? Is it by the UI or the call out size?

This is important because better deals can often be found in standard call out size windows. Unfortunately, most applications call for custom sizes; but it never hurts to ask.

Just in case, here's a short list of standard window widths and heights. A standard call out size may contain any combination of these measurements.

Widths: 16" 18" 24" 28" 30" 32" 36" 40" 42" 44" and 48"

Heights: 24" 28" 32" 36" 40" 44" 48" 52" 54" 60" 62" 64" 66" 72" 74" 76" 78" and 84"

Example call out size: 18" width and 52" height is a 1644 call out size, i.e. 1' 6" wide by 4' 4" height.

General rule # 1: look for a price per UI around $1.30 base window cost with no options.

Your next question is to ask what the window prices are with and without installation. This is important because sometimes companies advertise a low window price and pad the installation. So make sure this is an up front question. Then you can ask the installation cost.

General rule # 2: look for an installation price roughly 50% of the base window price with no options.

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Even though each project is different, there are two primary installation procedures for replacing windows. The first is called a retrofit installation and the second a frame and flange installation.


In retrofit applications, the existing frame, along with its existing interior and exterior trim pieces, remains in the wall. The replacement unit simply "retrofits" between the existing frame components and then attaches through the side jambs.

This is the cleanest and most time effective method since there is no actual rebuilding of the window opening or refinishing the interior. With this method, the exterior trim pieces (the brick molding and sill) are wrapped in a weatherproof vinyl or aluminum cladding and then sealed.

This is an effective way to do things. The new windows are then insulated and often times finished out with a small interior trim price to cover any rough edges.


With frame and flange installation, the old window unit is completely removed and replaced with a new and complete window unit. The new window is installed by nailing through an attached nailing flange into the existing window (rough) opening. This method is used when interior and exterior trim need to be replaced due to rot or other damage or the consumer wants an overall more integral window and wall application; it does require more time and expense however.

The principal benefits of retrofit applications are cost effectiveness, time savings, and a less invasive installation. Frame and flange applications offer greater window unit integrity, larger product selection, and more options for various colors and finishes.

General rule # 3: Greater selection is available in frame and flange installations but look to pay more for the installation; sometimes 25% additional.


If you haven't read my HUB on how to understand window energy ratings, I suggest you do so since some of the terminology introduced there is discussed here. Nevertheless, here's a list of options you'll want to ask for specifically (and have priced separately) when choosing your replacement windows.


This is a must when purchasing new or replacement windows since the energy savings far outweigh the initial cost. Typically, you should expect to pay between 10-25% depending on the product being used. For example, taking our standard 36 x 60 window with a hypothetical price of $125.00, the Lo-E up charge should be between $12.50-$31.25.


Argon is usually sold along with the Lo-E glass. A typical up charge should be 6-12% on top of the Lo-E up charge


These are the metal or vinyl bars placed between the panes of insulated glass to add a sense of multiple lites and aesthetics. Some manufacturers charge by the lineal foot and some by the unit as a whole. If priced by the lineal foot expect to pay between $1.50- $3.00 depending on the type of grill ordered.

An easy example using our 36 x 60 window would be as follows. A common lite pattern for such a window is 6 lites over 6 lites. This equates to (2) 36" horizontal grilles (1 for each sash) and (4) 30" grilles (2 for each sash). Our total lineal footage is 16' multiplied by the lineal foot price. Using this formula, the up charge would be $24.00 on the low end. The lineal foot charge is typically used for specialized grilles such as beveled, sculptured, or metallic.