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Restore Those Old Windows

After having worked exclusively on the restoration and repair of older wooden window sash for a number of years, I am pleased to see a resurgence of interest in window restoration, as well as discussion of the merits of original versus replacement windows.

This early 1800s house has much of its original crown glass intact, and the wooden sashes are in very good condition. Original site-made sash yokes are still in the jambs, which were rotated upward to hold the bottom sash in an open position. (Click image to enlarge. Hit "back" button to return to article.)

I live and work in Richmond, Virginia, an historic city with many interesting buildings and building styles: Federal-style houses from the late 1700s, Greek Revival, Italianate, Second Empire…. All are unique, and have many different types of original window sash, which, until recently, was very difficult to replicate with new products.

The replacement windows used on antique buildings are often horrendous, ranging from the “blank stare” look of large single pane windows with fake interior mullion, to divided lite replacements with larger than original mullion that never seem to look just right.

Admittedly, I am biased, but I appreciate the original wood windows for three basic reasons: superior materials used in their construction, craftsmanship, and, finally, design.

Most of the sash that comes to my shop was made from long-leaf pine—old-growth wood which was often harvested after standing for two to three hundred years or more. Now nearly extinct, this wood resists rot and insect damage, and is extremely hard. Compare, for example, a 150-year-old sash to replacement sash just ten years old. When you cut into the old sash, the fragrance is like opening a can of turpentine.

Another wonderful material found in old sash is antique glass, often called “wavy glass” because of its distortions. (The actual terms are “crown glass” for glass made from about the late 1700s, or “cylinder glass” for that made from the 1850s until the 1930s). Early glass manufacturers wanted flat glass like we have today, but they were unable to produce it. Today, the wavy look of old glass is prized by old house owners, just like old car buffs prize original parts on an antique car, or furniture collectors cherish original fabric on an old piece of furniture.

These locks represent hardware found on sash from the early 1800s through the Victorian era. All were indistinguishable globs of paint before being cleaned.

Metal parts of the window are also unique and should be retained whenever possible. Sash-locks, pulleys, and finger-pulls, which were typically well-made in the past, are good-as-new after cleaning. Often, when these items are stripped of a century or more of paint layers, they reveal hidden details that can offer a pleasant surprise.

Old sash was originally made with wooden sash planes. Mullion were later machined, but still designed with a thinner, more delicate profile than you find in modern sash. Joinery was typically through mortise and tenon rather than glued and stapled butt joints.

According to Wendy Nickolas, director of the northeast office of the National Trust for Historic Preservation, “The National Trust for Historic Preservation encourages owners to repair and retrofit their existing older and historic windows whenever possible, rather than tossing them into the landfill and installing replacements. Repair is usually more cost-effective, and can achieve comparable energy savings.”

The slender mullions on this Victorian porch are emphasized by the height of the sash, giving an aura of elegance to these floor-to-ceiling windows.

Admittedly, replacement windows are getting better. Many are designed to be more compatible with older structures. But, offered a choice, I would keep the original ones. New products are available today which can weatherize old windows quite effectively.

After restoring an antique window, I always advise clients to finish with a low-profile exterior storm window. This secondary glazing will protect the restoration work—especially the new glazing compound and paint coating—and is approved by The Secretary of the Interior’s Standards for Rehabilitation.

If you’re seriously considering restoring your old windows, and want to know more about the subject—for example, how old glass was made—here’s a book you should consult: Repairing Old and Historic Windows, New York Landmarks  Conservancy (John Wiley and Sons, Publisher). It covers the subject from A to Z. I have no interest in the company, but this is one of the best books I’ve seen on the subject.

The curved sash on the second, third, and fourth floors were blown out of this building during a storm. Rather than replace the windows with rectangular sash, the originals were joined together and epoxied, allowing this Beaux Arts structure to keep its architectural integrity.

Also, if you want to retrofit modern weather stripping into your old windows, there’s a step-by-step guide in the archives of Old House Authority (

In addition to these resources, one can find a wealth of information from the National Trust for Historic Preservation. Their address is 1785 Massachusetts Ave. NW, Washington, D,C. 20036, phone: 800-944-6847, email

The National Trust has prepared guidelines and directions for restoring and maintaining original windows, complete with a number of resources one can consult (you can download the PDF here). They’re right on the mark when they say that “historic windows are among the most important elements of a building.” They also assert that, when restored and maintained properly, the efficiency of original windows will match, if not exceed, that of replacement windows. I wholeheartedly concur.

(Photos by Maurice Duke)



Dixon Kerr is a partner in Old House Authority, a Virginia-based business that promotes historically appropriate renovations. A long-time woodworker, Dixon manages Old House Authority Window Restoration. In addition to restoring windows and salvaging carelessly discarded historic sash and glass, he shares his knowledge through teaching and writing in the hope of promoting the preservation of original windows. Having been involved in restoration for 20 years, Dixon co-founded The Alliance to Conserve Old Richmond Neighborhoods in 1999 to help preserve vacant and abandoned buildings in the city’s oldest neighborhoods.

Dixon’s love of woodworking developed in the 1970s, when carpentry was experiencing a renaissance. He is a fan of styles ranging from Shaker to James Krenov’s modern. Soon after the publication of “A Cabinetmaker’s Notebook,” Krenov visited the woodworking school Dixon attended, which taught 18th century hand joinery. Classmates showed Krenov a box Dixon had made—a knock-off of one of Krenov’s pieces—which pleased the master craftsman. Window restoration turned out to be the perfect combination of Dixon’s interests in woodworking, preservation, and discovering things off the beaten path.


11 Responses to “Restore Those Old Windows”

  1. Brady

    Thanks Dixon for all the great resources you list in your article and I think you are “spot on” about the elegance of original windows versus today’s replacement windows. I do wonder what your thoughts are with regards to the lead paint present in most older windows … especially with regards to the EPA’s RRP requirements that went into effect in April … Seems to me that removing and repairing old sashes is likely to disturb lead-based paint. I would guess careful removal and getting them “dipped” at a local paint stripping facility would be the best bet to mitigate lead dust concerns?

  2. Ed Burt

    Would love to see an article on restoring old windows, particularly, the basics of glazing from an expert like you.

  3. Hartley Edmonds

    Nice article. Your references are very welcome. I’ll learn from them and use them to help clients better understand the necessary tradeoffs.


  4. Wendy Nicholas

    Very helpful article, Dixon. Thank you! I would add that the National Trust for Historic Preservation’s website, has a wealth of information and links for people interested in repairing historic and older windows, in weatherizing historic properties, and in this question re: the new lead paint regulations.

  5. WaysToSave

    I recently restored a few of my old storm windows. It has the “wavy glass”. Most of the cost is in the labor. I did it myself, so it cost only about $60 for 2 new glass pieces.

  6. Tim Johnson

    Thanks for the great information, especially about the National Trust for Historic Preservation. This will be most helpful in my future ventures.

  7. Catherine Brooks, Eco-Strip

    Dixon wrote a detailed, step-by-step article on how to restore old windows in Journal of Light Construction in July 2007. Go to and search the Archives. Unfortunately, an Archive Membership is required. Soon it will be posted on the Resource/Links page of

  8. Charles Hutcheson

    I have mullions in my windows. A squirrel destroyed some in my garage. Where can I find replacements? This Is much harder than I thought it would be.thanks for any help offered.

  9. Olek Lejbzon

    We restored three hundred windows for NYC Transit- MTA: White Plains Rd, after being covered by corrugated steel for more than 50 years. It wasn’t easy, the old sills were hacked off with hatchets, to cover flush with the steel “protection”

  10. Paul Denys

    FYI. I am a founding member of WPA(Window Preservation Alliance). Founded in April 2015. We have members all across Canada and USA doing this type of work. I have been doing this type of work since 1988.


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