Replacement  vs New  Construction Windows

Replacement (Retrofit) Windowbeautiful home exterior

Replacement windows are made to replace existing windows with minimal new construction.  Using replacement windows to upgrade your existing windows can save you time and labor costs over using new construction windows but can in some cases, also mask underlying structural issues.


Replacement windows usually come in two types: Flush fin or Block frame. Flush fin windows are primarily used for homes with stucco exteriors. Flush fin windows are standard replacements for windows with aluminum window frames.  Using a Flush fin window will leave your original window frame intact and will also avoid damaging stucco if you have that as your home exterior material.


Block frame windows are replacement windows for homes that currently have wood windows. Typically, Block frame windows are the standard replacement for most older homes, and these are the types of windows you will probably be reviewing for installation in your home improvement project.  Block frame windows are also designed to replace windows on homes with siding or brick exteriors. There is very little difference between a Block frame window and a New Construction window, typically the only noticeable difference is that the Block frame window will come without a nail fin.  This is done because the window is designed to fit inside existing window flashing with minimal new construction work. Using replacement windows can be more cost and time effective because they do not require your contractor to strip back to the studs in order to install the window.


New Construction Windows

New construction windows are different from replacement windows in that they typically have a nail fin around the edge.  A nail fin is material around the edge of the window that will rest against the stud of a new wall and is designed to hold the nails that keep the window in place. Once the nails are in, the exterior materials like trim are applied around the window fully integrating the window into the wall.


If you are using new construction windows for a replacement window project, all of the existing trim will need to be removed down to the wood studs and then re-installed as if it was a new construction project.  One benefit of this longer process is that it will allow your contractor to see the current state of your original wall studs and look for damage.  This damage can then be repaired during your window replacement project and save you a problem later on. Using new construction windows as replacement windows will also ensure that you have proper insulation and air filtration around the windows since you are starting with the studs and building back up.  However, you need to take into consideration that all of these things will cost extra time and money increasing the overall cost of the project.


Finally, no matter whether you choose New Construction or Replacement windows you must be certain that you understand the differences in quality of construction and performance.   Be sure the product you select is ENERGY STAR® Qualified and review the NFRC windows 101 graphicratings before you make a final decision for your home project.  In addition, you may want to consider performing research about the window manufacturer.  After all, you want to be sure that the manufacturer will be able to uphold its warranty should anything go wrong with your new windows.


For more on ENERGY STAR® and NFRC Ratings be sure to review our Guide to New Windows.