All About Historic Windows

4 pane casement window

For me, windows are one of my favorite, and at times, most challenging  (they’re one of the few parts of a house with lots of moving pieces!) aspects of a classic home. Windows truly are the eyes of your home and I have seen too many homes with a black-eyes over the years. A home and its occupants look out onto the world through these sometimes simple, sometimes complex contraptions to keep out the elements and let in the light. And the world learns a lot about your home by its windows.

A Brief History
In the first homes windows were more than a decorative way to light the room. Originally, there was no glass, simply a crude opening designed to let fresh air in, smoke from the family’s fire out, and light the space. This lack of glass was the reason for the first shutters. After all, you didn’t want a hole in your wall during a rainstorm or a brutally cold winter, not to mention all the bugs. Eventually, glass came into the picture. First for the rich and the nobility and then slowly to rest of the masses.

Up until 1900 all glass was handblown and large pieces were very expensive. The expense and relative unavailability of large pieces of glass resulted in windows with several “lights” (meaning individual panes of glass) being the trademark of the days. In 1900 a new technique was invented and the predecessor to modern glass, called machine-drawn glass, was born. Hand-blown glass was mainly good for letting light into the room as the images seen through the glass were usually a blurry mess. Machine-drawn glass greatly improved the clarity and consistency of glass but was still far from perfect. As glass making skills increased, the size of individual panes increased as well resulting in new combinations such as 6-over-6, 4-over-4, 3-over-1, 2-over-1 and eventually glaziers could construct a window out of a single pane of glass.

Windows are typically described by their number of panes (6-over-6 has an upper sash with 6 panes and lower sash with 6 panes) and by the way they open (ie. double-hung has 2 sashes the open independently of each other whereas a casement window swings in or out on hinges).

9 over 9 double hung windows

In 1959 modern glass, which is the type still used today, was invented and glass could be had in almost any size with a uniform thickness and flawless clarity. But those of us who like the special “glimmer glass” in our old homes that was the day windows with character began to die.

What Kind Do I Need?
Today you can buy windows in more forms than our forefathers could have imagined. Double, triple, even quadruple-paned windows filled with inert gasses like argon to prevent heat or cold transfer. They have become an efficient part of the house yes, but when dealing with a classic home from generations  past an out-of-place window from the wrong time period can destroy a beautiful facade. Windows of yesteryear each had a purpose and served a function. For example, double-hung windows were designed with an upper and lower sash that could be opened independently of each other. The top sash (which on most older homes has been painted shut over the years) was designed so that in the days before air-conditioning warm air could escape from the house and be replaced by cool air entering from the bottom sash.

The anatomy of a window (courtesy Old-House Journal)

Pre-war windows were also glazed with linseed oil putty to make the panes airtight. Caulking may last for years, but it doesn’t come close to the 80 year life span of properly cared for glazing putty. Also, being made from old-growth timber, original windows are surprisingly rot-resistant. I’ve had to completely rebuild only 2 windows out of the 32 on our 1929 bungalow, and those 2 were the only non-original windows in the house! The 2 replacements were a mere 20 years old before they succumbed to the elements!

So, before you decide to replace your drafty old windows stop and think. They can be restored to their original appearance, working condition, and efficiency with period weather stripping (copper not foam or rubber).

If you’re not sure about whether your windows are candidates to be saved visit our resource page on How To Restore Old Windows

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by Scott Sidler

I'm a historic preservationist and licensed contractor. I help old house lovers understand & restore their homes so they can enjoy the history and character that surrounds them more everyday! When not working, writing or teaching about old houses I spend most of my time fixing up my own 1929 bungalow with my wife Delores and sons Charley and Jude.


  1. Rob Jerman on said:

    I am restoring a 1790 stone farmhouse in Bucks County PA and am building 9 over 6 sashes for the first floor windows that were retrofitted with 2 over 2 sometime in the late 1800s or early 1900s. I see 6 over 9 and mostly 9 over 6. is one right and one wrong or were they both used? also looking for design details about how the meeting rails came together. I am using an old ovolo sash plane that was from the early 1800s that matches nicely the sash molding on the upstairs windows…

    • Wow! Building new sashes and doing it with a sash plane to boot!! Well done! As for the lite pattern 6-over-6 and 9-over-6 were both common and it just depends what was originally done. For that age home more and smaller lutes is likely a better plan, but without pictures or old sash it’s hard to know what was there before. Keep in mind too that 1790 sash were likely less than 1 3/8″ thick unlike the sashes from the mid 1800s and later.

      • Robert Jerman on said:

        Thanks Scott. I am making them thinner than what was there.. a bit thicker than the upstairs, a bit over 1 inch. the question was 9 over 6 vs. 6 over 9, you may have misunderstood me… the combination fits in the opening perfectly but I have not been sure which should be on top!

        • Both are historically accurate so there’s no real way to tell. I would look locally to any other buildings the same age and see what if anything was typical in your area at that time.

  2. My 1910 Classical Revival bungalow possesses remarkable historic integrity in most respects. Unfortunately, the original double hung sash (and wavy glass!) was replaced with aluminum in 1984. Fortunately, the original casing remains intact. My house was built by the first generation of an African American family to be born in freedom. It is modest in size, fewer than 800 square feet, but it has style. The four doric columns that support the porch roof are called out specifically in the NRHP listing for the Tenth Street Historic District (Dallas). The house has only eight windows. The four largest of these are 30″ wide by 78″ tall. Any ideas as to what the original glazing pattern would likely have been? I assume each sash would have measured 30″ wide by 40″ tall with about 2″ overlap when the windows were closed. I would like to restore my home with vintage sash and wavy glass, but I think the height of the windows may pose a challenge. Suggestions?

  3. Carol Hughes on said:

    I live in historic Nazareth, PA I have 34 sashes from a 1929 home to sell. White on the outside..natural stain on the inside.

  4. Amy DeFilippo on said:

    Hello. I just purchased a very old Awning Window (Transom?). It is very old, cased in wood with hinges and the name: Pine-Hurst and below that is the number *503*. Do you know anything about these types of windows? Would this be the address or name of business/law firm? Thank you for your time-Amy

    • Not sure, Amy. It might a model and model number of a company’s window. If it’s newer than 1920s that’s likely the case. Otherwise it might take a little more detective work.

      • Amy DeFilippo on said:

        It is actually painted on the glass. Sirry, I should have been mire specific. It is painted in bkack, Pine-Hurst then underneath that is the number *503*. It’s not in the gold leaf letters that you typically see. It is in black. Thank you! Amy

  5. ferni on said:

    Hello. Is there a standard size for the small square glass(about 8×8)in a craftman house window? Thnak you

    • Ferri there are standard sizes but there are dozens of them.

  6. Angela Wright on said:

    we are about to restore a 1929 bungalow in Birminhgam AL. Unfortunately all the original windows have been replaced with cheap ones. Where can we find old windows to replace the replacements?

  7. Jyll on said:

    The windows in our 1843 house do not have weights. Instead, they have pegs in the sides that fit into holes in the frame to keep them open. The glass is very wavy. Do you think these windows are original to the house?

    • Jyll, absolutely! That hardware is often called a sash spring bolt and they are a common alternative to rope and pulley systems.

      • Jyll on said:

        Thank you. House was just purchased in summer of 2015. Trying to figure out original layout of rooms. Good to know the windows are original.

  8. Brian on said:

    Just started restoring original windows of our house built in 1900. The first window that I’ve started stripping has revealed a jet black charcoal-like coating under the paint. It’s not coming off easily. What is this and how do I remove it?

  9. Hazel on said:

    Dear Scott
    All i need are the 2 windows no frames no sills no hardware as they will be permanatly fixed as they were when the carriage house was built. I just need to know how much each window will be with the shipping cost.

    Thank you

  10. Hazel on said:

    i would need 2 please or name of company that can make them the local lumber & window companies are suggesting plastic replacements & that just will not work for this beautiful old building.

  11. Hazel on said:

    I am restoring a 1709 home & the carriage house on my property has 9 over 6 windows. i am looking for 2 of them. i have the antique glass just need the windows.

    • What happened to them? Are the windows boarded up?

      • Hazel on said:

        the 9 over 6 windows that i am talking about have been weathered by time & they have rotted in place so i need to have new ones made. i have the dimensions for each window. the height for the 9 pane is 30 1/4 height & the width is 24 3/4 & the 6 pane is 21 height & the width is 24 3/4. I have a phenomenal contractor to put them in once they are made. Is there a way you can make them & ship them to me at my expense?

  12. I have a house built in 1700 which already had windows replaced. I am looking for new windows to replace the ones I have that are more authentic to the house, like 9 over 9 or 9 over 6. Any suggestions? I want something that feels fairly authentic.

    • David, there are a lot of window restoration companies out there that can build new windows for you that are exact replica’s of historic windows with counterweights and all. That way they are as authentic as possible! I would check in your local area and see who can do that for you.

  13. Kim on said:

    I need some expert advice. I am considering buying a home build in 1959 that has all the original metal crank out windows. There are several glass slats per windonw and they are not wide enough to crawl out of in case of fire. I love the windows and would love to keep the character of the house, but what is the plan for fire escape with these type of windows?

    • Kim, it sounds like you have jalousie windows. There isn’t much you can do about opening these windows for egress means. Usually there should be an egress window in each bedroom that is openable.

  14. MIchael on said:

    Hello, I have an 1850s house. It’s a bit of an odd ball as it is a timberframe structure with a brick skin. The timbers on the main floor are about 8 x8 and the halved logs that form the floor joists in the basement are huge, the smallest being 16 inches wide. I have one original window left, it was a 2-over-2 design. The middle pieces of wood (is that a mullion/stanchion?) were removed at some point and single panes of glass were installed. I guess to match the newer ones which are 1-over-1. The tenons are still visible though. I suspect that the downstairs had the 2-over-2 windows and upstatirs had 6-over-6. Our garden shed has old 6-over-6 windows that are the exact size of the newer ones in our upstairs. I would eventually like to restore my one remaining window and have nine replicas built to replace the Pella ones I’ve got now. I would also need storm windows and screens. Would you have any contacts in Ontario/Quebec, Canada or in the Northeastern US? Or anywhere, if they are interested in lost distance customer relationships and offer shipping, of course. Thank you!

    • Michael, there are a lot of window restorers in the Northeastern US that I know. What city in Canada are you in? Or what’s the closest US city?

      • Michael on said:

        Hi Scott, Thank you for your reply! I live outside of Montreal. The closest US regions are the Adirondacks and Vermont.

  15. Carol Mariani on said:

    I love this website and the idea of keeping the 1922 windows in the Craftsman i own is exciting. However, i have neither the time, inclination, or talent to do it “myself”. Do you know of anyone in the San Diego area who does this kind of thing? It’s impossible to call a window company…all they want to do is replace. I guess it just as to be someone who specifically works on old homes. Help! Carol

    • Carol, try Window Restoration & Repair Co. In Los Alamitos, CA (562) 493-1590

  16. What made you decide to fully replace your windows, Robert? If the wood rot is significant and would require lots of repair labor, I can understand your choice. For only 6 windows, you can do the work yourself of restoring the windows. Scott’s other blogs and videos are fantastic in showing you how to do it. The cost is likely about the same to restore as replace. Consider it a challenge and go for it!

  17. Robert Bullock on said:

    We are restoring a ca.1850 house. I would like to buy 3 sets of sashes (for 3 window openings). Each sash is 9 over 9, 28″ wide and 34 !/2 inches high. How would I locate such sashes? If they were made, how much would each cost (I would install and supply antique glass). Robert Bullock, Oak Hill,AL

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