New Construction Type vs. Replacement/Insert Windows

By Scott Simonsen, Owner, Old World Craftsmen, Greenwich

Overview. When clients are considering replacing windows, they often ask whether they should do “new construction” type windows or “replacement” or “insert.” It’s a great question and this article addresses what factors to consider when making this decision.

Before we start, let’s be sure to define what these two window types mean:

New Construction Type Windows

This type of window fits into the framing of your house – in the trades we call the 2×4 or 2×6 framed openings the “rough opening”

The window has to go into the “rough opening” and then the exterior trim is applied on top of the nailing flanges at the window exterior.

This means if you plan to replace your existing windows with “new construction” type windows, all of the interior and exterior trim will have to be fully removed and replaced. It’s much more labor intensive, but it’s a more complete job. Here are the steps for a properly installed new construction window:

Process

• Site and dust protection
• Removal of all interior and exterior trim
• Removal of the old window entirely
• Adjusting the existing opening to precisely fit the new window
• Install the window and install flashing tape on top of the flanges to prevent water and air infiltration
• Install low expansion foam insulation between the window frame and the stud opening
• Install new exterior trim (usually Azek or PVC type)
• Adjust the siding or cut it back to receive the new trim
• Install new interior trim (and sometimes extension jambs)
• Touch up any sheetrock or plaster damaged by the project
• Caulk the interior and exterior
• Final cleanup
Estimated Labor for a Single Window: 2 Men x 8 Hours

Replacement/Insert Windows

This kind of window is custom made to fit inside the jamb of your existing windows. The process is much more surgical.

Process
• Site and dust protection
• The interior stop moldings are cut with a razor blade
• Remove the storm windows and the window sashes only (the operating part)
• If there are sash weights in pockets (windows before 1940 or so) they should be removed
and the sash pockets filled with insulation,
• Install the new insert window into the old window jamb, shimming to level and square
• Install low expansion foam around the window frame
• Re-install the stop moldings or install new
• Caulk interior and exterior.
• Optional: Install blind stop covers. High quality insert windows like Andersen units come with composite blind stop covers to cover ugly exterior moldings that were often covered by old aluminum storm windows
Estimated Labor for a Single Window: 1 Men x 3 Hours
Option: 1 Man X 1 Hour. To cut and install blind stop covers

How to Decide

Key Factors When Deciding

Key Factor 1:
The single most important factor that pushes the decision one way or the other is the condition & look of the trim on the windows. If your home has beautiful or authentic trim work inside and out, a replacement window will preserve these lovely moldings. If your exterior trim is rotten or your interior trim is flimsy or covered in paint gobs from years of sloppy painting, only a new construction window will address this. It gives you a chance to customize the moldings inside and out to your taste.

Key Factor 2: Window Type
If you have double hung windows in your home, these are generally the ones conducive to replacement/insert windows. Casement, awing, or interesting angle or round windows will usually have to be new construction. See our Window article [What is The Best Window For My Home?] to learn more about window types.

Note about Glass Size: Because they fit into the frame of the old window, replacement or insert type windows lose about 1 ½” – 2” of glass. Essentially ¾” for the new frame of the window inside the existing frame.

Other Factors to Consider:

Are you doing other work?
Most of the time we are doing a renovation project in a room, we’ll recommend a new construction type window since it’s the highest quality installation and there is already the need for home and dust protection for the other work. If the sheetrock is removed, it means the interior trim will be removed anyway, so you’re half way there to new construction anyway.
An exception: if a house has beautiful or authentic exterior trim, and a perfect match is desired with other windows, we sometimes recommend an insert style window.

Whole house window installation
If you are replacing all of the windows in your home, most of our clients choose a replacement/insert style window. It’s a rare client who wants to repaint 1 or two walls and window trim in every room in their house. And unless you are moving out, it will mean a construction crew in every room in your home. The replacement windows are a surgical process with minimal dust and each room can usually be completed during a workday (while the kids are at school!) and cleaned up for the client to use by the end of the day.

Closing Thoughts about Quality
I hope this article helps make the decision about which window is right for your home and project. Whichever window you choose, remember that the installation quality is crucial for the performance of the window. Any corners cut on shimming, squaring, leveling, insulation, caulk, and fastening will mean your air and water infiltration issues are not solved even with a new window. A window not meticulously squared in the opening will give you years of trouble and may bind or not even lock properly. Some people think a dedicated window company will give them the best installation, but not necessarily – some of them are pretty “cheap and dirty.” So be sure to carefully evaluate your installer before hiring. For tips on this, check out my article on [How Do I Select the Best Builder?]

Scott Simonsen is a graduate of Cooper Union’s select Electrical Engineering program. He spent three years in communications and electronic design before identifying his true passion—construction and home remodeling – launching his Design-Build firm, Old World Craftsmen LLC, in 1998. With his engineering mindset, Scott brings to projects a keen design sense and engineering problem solving approach – a rare combination in construction today. Scott takes pride in applying modern construction techniques with the old-fashioned care and craftsmanship that has been the foundation of Old World Craftsmen.