Tom Shafer

Do you need a replacement window or a new construction window?

January 23, 2014

If you need windows for your home, you might be confused why "replacement windows" keep being suggested to you instead of what you (like most people) probably call them: new windows. As we've discussed in the past, replacement windows are, in fact, new windows - but they're called something else to help keep them distinct from new construction windows.

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New construction windows go into brand new buildings and include every last piece and part of the window - most notably the frame that becomes part of the building's structure and in which all future windows will sit. So why can't you just buy a new construction window instead of a replacement window? Well, while replacement windows have a square, flat frame, new construction windows have a nailing fin, or flange, all around the window frame's edge. It's nailed directly into the house. If you want a new construction window, you'd have to rip out that nailing fin (which will definitely be difficult and destructive and might be near-impossible depending on your home's exterior). A replacement window, on the other hand, slides into the existing frame - no mess, no extra construction/destruction required.

If you're building a brand new structure, however, new construction windows are in your future. The nailing fin will be nailed or screwed directly into the rough frame of the building. The rough frame (or rough opening) is usually a half inch larger than the window frame. So if, for example, you're installing a window that is 32" wide, your rough opening will probably be 32 ½ inches.

The nailing fun is normally set about one inch back from the front of the window. This inch gives you room for insulation and siding (which typically runs ½ or ¾ of an inch). The space left is used for the decorative trim on the window's perimeter. Depending on where you live and what your home's exterior is made of, your window trim options will vary. Brick molding is used on brick houses, for instance, while standard clapboard siding (like that on many homes in New England) are suited to flat 4" wood trim. Some buildings are able to forego window trim entirely.

If you're in an area where stucco is the primary exterior siding used (like Florida or California), don't be surprised if a nailing fin isn't used at all. Instead, you'll see a ½ to ¾ inch flange on the front perimeter of the window. This is placed against the wood framing for a water-tight seal and then covered with stucco.

No matter what kind you need, you can find window experts to help with your project and give you an estimate. Now that you know which type of window you're installing, you can even start thinking about energy-saving models with some help from Energy Star.

About the Author

Tom Shafer has decades of experience in window sales, marketing and product development. He's worked closely with window design engineers in testing, design, and building code interpretation. Past employers include United Windows and Doors and Norandex, MI Windows. He currently works at a home improvement retailer.

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