Replacement vs New Construction Windows

Replacement vs New Construction Windows

We use a lot of jargon in the window industry. In this post we’ll introduce you to some of our jargon and explain the differences between replacement windows and new construction windows. 

What is a Replacement Window?

Replacement windows are designed for easy installation into a pre-existing window opening.

If you’ve done some research into what replacement windows are or how replacement windows are installed you’ve already heard a lot of the terms we use. Some related words include retrofit windows, full frame window replacement, flush fin windows, block frame windows, and insert windows. We’ll explain the differences between all of these terms below. 

Retrofit Windows

Retrofit windows is a synonym for replacement windows. Replacement windows are installed into pre-existing openings with little to no disruption to the home. 

Full Frame Window Replacement

Full frame window replacement is a replacement window installation process that requires fully removing the existing window down to the original rough opening for the window (down to the original studs of the wall). It’s a misconception that only new construction windows are used for full frame window installation projects, block frame windows are also used for full frame installations because they are also installed into a rough opening. 

Image Credit: Brennan Enterprises

Insert Window Replacement

Insert window replacement is a replacement window installation process that calls for pocketing a fully assembled window within an existing frame (imagine a secondary frame within an existing frame). Insert windows are sometimes also called pocket windows and are typically used with original solid wood window frames only if the original frame is still in good condition. 

Image Credit: Brennan Enterprises

Block Frame Windows

Block frame windows include the window’s mainframe (left and right jambs, top header, lower rail) and all the operational parts of the window within (sash, glass, hardware, etc.). Block frame windows look similar to new construction windows except they don’t have a nail fin around the perimeter. We use block frame windows in full window replacement projects.

Flush Fin Windows

Flush fin windows are typically used for installation in homes with stucco exteriors (they can be used on other home exteriors but are most common on stucco). They’re sometimes called flange windows, z-bar windows, or jump frame windows. Flush fin windows are similar to insert windows and sit within an existing window frame. The exterior fin extends far enough to hide the existing frame. Learn more about flush fin windows and why and when we use them in the video below.

Image Credit: Brennan Enterprises

Sash Kits

Sash kits are also used in window replacement. Sash-replacement kits are installed on existing window frames giving the frame jamb liners and sashes. 

What is a New Construction Window?

New construction windows are made for new buildings and installed when the studs or sheathing is still exposed. The design of new construction windows includes a “nail fin” which is basically a center flange around the perimeter of the window frame. The fin is used to fasten a window into place and helps with waterproofing.

Image Credit: Kody Harvey↗

What’s the Difference Between New Construction vs Replacement Windows?

It’s a common misconception that new construction windows and replacement windows are different windows when in fact the manufacturer makes the same window and asks what application it the window will be used in–new construction (with fin) or replacement (no fin). That’s the biggest difference between new construction windows and replacement windows–the nail fin. The nail fin is placed against the framed opening and nailed or screwed to the framing, providing an additional layer of protection against water and air infiltration. 

In new construction applications, you can frame openings based on the windows you’ve chosen but in replacement applications you work with the existing openings. Replacement window professionals can make the process easier by anticipating and helping you address any problems with the existing framing or exterior of the house. 

What kind of problems might you run into in a replacement window project?

Over time your house will settle and be exposed to nature’s elements, this can affect the condition of framing including rotting or warping. Existing problems and potential problems need to be taken into account when deciding on which type of replacement window and installation process is used. This includes ordering the right size window for the existing opening. Replacement window technicians need to take weatherproofing into account because replacement windows don’t have the protection that nail fins provide for new construction windows. 

Image Credit: Brennan Enterprises

Do I Need New Construction or Replacement Windows?

Choosing between new construction windows and replacement windows is usually pretty straight forward. In new construction buildings where the studs are still exposed you’ll choose new construction windows with a nail fin and in small remodeling projects where you’re using the existing opening you’ll choose replacement windows made without the nail fin. 

For a renovation using the existing opening?

Choose replacement block frame replacement windows. Block frame replacement windows are used in full frame window replacement projects. Window technicians remove the existing window down to the original rough opening and use this opportunity to look for hidden problems. Professionals order windows made to the proper size for the window’s rough opening minimizing any unnecessary space around the window unit. Properly fitting windows are necessary to prevent damaging water or air infiltration.

For a remodel creating a new opening?

Choose a new construction window. If you want to create a new opening in an existing wall or an addition, the opening for the window will need to be framed. Choose a window with a nail fin that can be attached to the exposed studs. 

For a remodel converting a door to a window?

Choose a new construction window. When converting a door opening to a window opening new framing is required to create the appropriate size opening for your new window. New framing means the studs will be exposed making it possible to install new construction windows. 

For a remodel expanding an opening?

Choose a new construction window. Whether you want to install a bigger window or smaller window than the existing opening allows, your team will have to reframe the wall cavity for the new replacement window. Choose a window with a nail fin so that it can be completely attached to the new studs. 

I have old wood windows but haven’t had any leaking and the frames are still good, do I need new construction or replacement windows?

Choose insert windows. If you want to keep the cost of your project low or you want to keep the original wood frames choose insert windows. Insert windows are an option for wood window frames that are still in good condition. When the wood frame is still in a good condition a new window unit can be installed within that frame but it does reduce the amount of visible glass surface. 

Can New Construction Windows Be Used for Replacement?

New construction windows can be used for replacement window projects in two ways. Remember, the only difference between a new construction window and a replacement window is the nail fin. If you want to replace a window and are removing the wall’s exterior siding down to the studs of the wall you can use a new construction window with the nail fin. If you are doing a replacement project and aren’t exposing the wall’s framing you can remove the nail fins from the windows to avoid reordering windows without the fin.

Are New Construction Windows Cheaper Than Replacement?

New construction windows can be cheaper than replacement windows but the cost really depends on the quality and quantity of the windows you order. Windows made for new construction homes and builders in mind can be made at lower price points because of volume.

Your project costs will likely be higher if you have an existing home and want to do a remodel or addition using windows with nail fins. Renovations using existing openings are usually more affordable because less labor is required. With the amount of window manufacturers in the industry today, you’ll have lots of options at varying price points. We recommend working with an experienced professional to help you make the right choice for your home. 

Sign up to get our newsletter

A monthly email with our favorite articles about design, home products, tips and the occasional inspirational life lesson.