Historic Building Window Types
Your historic house or building might have any of a variety of different original window styles. If your original windows are damaged or not as energy-efficient as you would like them to be, you might be tempted to replace them with modern window styles. However, your original windows are an important character-defining feature of your building — and there are many great reasons why you should keep and repair your original windows. Before you start making repair decisions for your original windows, you should understand what type of windows you have and how they are constructed.
Window Construction Materials
The most common material used to construct original windows in historic houses and buildings throughout Wisconsin was wood. Pine was the primary wood used, but fir was used occasionally. All wooden sashes were made with one or the other, but never with hardwoods. Hardwoods have too much tannic acid and do not hold paint properly. Sometimes a hardwood veneer was applied to the interior side of window sashes.
The second most common window construction material was steel. Historic steel casement windows used steel made from iron ore, which made them more rust-resistant and structurally stable than today’s steel windows. Today’s steel is primarily made from scrap steel instead of iron ore. Some commercial double-hung windows were made from sheet metal formed into a channel that mimicked the size and shape of wood window parts.
In the mid-20th century, builders began to use aluminum double-hung, casement, and awning windows in residential and commercial buildings.
Double-Hung Windows
Restored 1859 true divided light, double-hung window. Source: Bob Yapp
There is a good chance your historic house or building has double-hung windows. The double-hung window is the most common type of historic window in Wisconsin. A double-hung window has one window sash on top and one on the bottom. Each of the two window sashes move up and down using a counter balance system. Up until about 1950, this counter balance was a cast-iron sash weight, a sash pulley, and sash cord to connect the weights to the sides of the window sashes. After 1950, double-hung windows were constructed with a spring balance. A large spring attached to the sides of the window sashes was used to lift and lower the sash. Most double-hung windows have an exterior storm window and a separate screen window. The screen covers the entire window opening so the top sash can operate the way it was intended.
Your double-hung windows were designed as an early air conditioning system. If you lower the top window sash three inches and raise the bottom sash three inches, two things will happen: the heat and humidity will leave your house through the top gap, and cooler breezes will enter your house through the lower gap. If you use your double-hung windows this way, you can save substantially on air-conditioning costs. This is one great reason why you should save your historic double-hung windows.
Most double-hung windows in residential and commercial structures were made with wood. Occasionally the double-hung windows used in commercial buildings were constructed with hollow steel channels. Often, double-hung windows had true divided lights (multiple panes divided by a wood or steel muntin). Some had leaded stained or colored glass, or even etched or beveled glass.
Casement Windows
Classic steel casement window in a Tudor Revival style house. Source: Bob Yapp
Casement windows were used in both houses and commercial buildings. A casement window has hinges on the side of its sash or sashes, much like a door. It might be made of wood or steel. Casement windows were used in residential houses from many different eras and in many different house styles. The casement windows used in historic commercial buildings were generally made of steel.
A casement window can be configured to open into the building or open outward. If it swings inward, it is sometimes referred to as a French window. Casement windows often have a storm window fitted on either the outside or inside depending on the direction of the swing. Most casement windows have brass or bronze hardware that tightly latches the window shut. Many casement windows have true divided lights (multiple panes divided by wood or steel muntins). Some have leaded stained or colored glass, or even etched or beveled glass.
Awning Windows
Wood basement awning window that is hinged on the top to open inward. Source: Bob Yapp
Awning windows have sashes that are hinged on the top to allow the window to open upwards and inwards. Older historic houses and smaller commercial buildings usually have awning windows in the basement or in stairwells that have limited space. Commercial buildings such as warehouses and industrial buildings often had steel versions of awning windows. Because awning windows were hinged on the top, they allowed massive amounts of air to flow through them when they were open. This characteristic made them ideal for letting heat out in the summer. They were also designed for storm and screen windows.
Hopper Windows
Hopper windows have sashes that are hinged on the bottom and open downward. Hopper windows are not common, but they were used in some mid-20th-century commercial buildings and houses. They were made of wood, steel and even aluminum.