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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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90 thoughts on “All About Historic Windows

  1. I recently bought an old house (1900-1920) still with all its original windows. I have noticed that some of the windows have small, thin, triangle-shaped metal pieces set into the corners between the pane and the frame. What are these called and why were they needed?

  2. What type of glazing do I use on a leaded window against wonderful old growth sash wood. The windows are from one of the two mansions P.T. Barnum built in Bridgeport CT. We had the lead glazing nicely restored 30 yrs ago before the windows went into their current fixed frames. Consider the house is in FL facing south yet gets several hours of blazing sun 11a – 3pm.

  3. I have a craftsman style brick home built in 1924 in Muncie IN. 8 of the historic window panes are cracked. I’m concerned that if I have the panes replaced, the windows will be ruined as they have the original ropes, pulleys and weights and are in great shape. Is it better to just epoxy the cracks or replace the panes? Any suggestions on people who know what they are doing in Indiana?

  4. I’m doing a scale model of an old one room schoolhouse for the Heritage Club of the modern day school and all I have is an old photo to go by (there are no scale drawings). From what I can tell of the photo the windows seem to be 9 over 6’s and the windows seem to be about the same width as the door, would it be safe to say the windows could possibly be about 3 foot wide by maybe 6 foot tall?

  5. I have a 1927 log cabin with steel windows. A quote from a restorer said this:
    Living room 74×51 14 fixed /12 double cmt w 6 cmt 1g- 1 opening
    These windows are all steel with brass push levers, hinges on outside. I don’t see ant info on old steel windows. Where can I get info on how to restore these?

  6. I have an 1896 miner’s home that has been remuddled many times over the years. I am working to restore back to what it may have looked like in 1896 and am looking for reference material that would give me some idea of style of double hung windows and interior trim and mill work. Any suggestions for reference materials/books?
    Thanks,

  7. We recently cleaned out the old barn on the property and we found some very large 4 pane glass, wooden frame windows. They all have 3 roughly 2″ circles in the wooden frame and a piece of wood that slides up and down to cover and uncover them…. has anyone seen this before or does anyone know what it was for?

  8. Is the weather stripping the vertical metal pieces the sash travels on? I’m needing to do some work on my c. 1930 windows and I cannot figure out how to get the sash off without destroying that metal piece. Tips or tricks?

    1. Its a little bit of a tricky process I spell out the steps in my book Old Windows In-Depth available in my store. If it was simple I’d be happy to share but it takes lots of pages and lots of pictures, but the long and short is that you have to remove the weatherstripping with the sash and reinstall it with the sash when the restoration is complete.

    2. Megan… What you describe are likely storm windows typically installed over the permanent windows (generally double hungs) during the cold weather months. The 3 holes were there to allow for ventilation on warm days (simply pivot the closure piece up to ventilate and then down to close it off).

  9. I have always been convinced of the value of older windows. My present home, circa 1915, has many 28×72 double hung (with weights) windows. I have restored all of them, BUT the previous owner replaced 12 of them with cheap aluminum products. Does anyone have an idea where I can find used windows (6 panes per window) of the above dimensions?

    Condition is not important; I am equipped to replace damaged wooden parts.
    I live in Central Texas and will travel to your location.

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