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Historic Windows: Part Two

This is the second installment in a series of blog posts on historic wood windows. This post will focus on my process for evaluating windows and recording important data and features. Before I undertake any restoration or conservation project or reproduce an historic window, I do a systematic and thorough evaluation so I can determine what needs to be done, how critical some repairs might be, and how to do perform the repairs. The extent of this initial analysis depends on the several factors, including the historic character of the windows, the goals of the restoration and the budget of the property owners. For instance, my evaluation of original windows in a historic house museum that are slated for complete restoration or conservation would be more in-depth than it would for the repair of 1920s replacement windows from a garage. The Rockford Area Historical Society generously gave me access to the Ames-Florida-Stork House a few weeks ago and I will use a window from this house as an example to show this process.

The Stork House is one of my favorite buildings in the area. The vernacular Greek Revival house was built in Rockford, MN by George F. Ames, a Yankee miller who formed a partnership with Joel Florida and Guilford D. George and developed a milling business on the nearby Crow River. The house is remarkable because it was built before the railroad had reached Rockford, meaning all the doors, windows and other millwork were made by hand on the building site. The house presents a wonderful opportunity to examine mid-19th century construction techniques, tools and materials used to build double-hung windows, doors and millwork.

The 1856 Ames Florida Stork House in Rockford, MN. The original 1856 section is to the right. Shortly after the main house was built a summer kitchen and a barn/carriage house were added. In front is a mill stone from the gristmill originally owned by George F. Ames.
A window inventory form and few of my measuring tools, including a tape measure, vernier calipers, and a molding contour gauge.

One of the first tasks is to document the window. I start with general characteristics, such the type of window (double or single-hung, casement, etc.), its glazing (is it a one-over-one, six-over-six, etc.) and where it is located on the structure. Then I will measure the various window components, including the dimensions of the window opening and size of the rails, stiles, muntins and mull (if it is a double window). I have a window inventory form I use to record all the construction details and measurements. I use a contour gauge to record molding and sticking profiles. I also make note of other construction details, such as whether the window has plain or matched meeting rails, whether the joints are coped or scribed, whether the joints are pinned with wood or metal pins, the details of the mortise and tenon joints and so on. I will also record other information, such as the type of finish, hardware, pulleys and weights, and type of glass. As I showed in an earlier blog post, even something as basic as a window will have many, many details that are important to know before I can start and restoration or conservation project. These details are especially critical when I am either reproducing an entire window sash or replacing one or more of its components using period hand tools (for a look at some of the period hand tools used to make windows, see Historic Windows: Part One).

Lower sash from one of the widows.

Once I have documented the dimensions and construction details I move on to an analysis of the window’s condition. Here I am looking at the sorts of things you would expect, including condition of the original finish and putty. I also look at the condition of the wood elements and search for rot, splitting, checking and missing pieces. In particular I want to know whether the mortise and tenon joints retain any integrity and whether the sashes are still straight and plumb. I also look to see if there is any missing hardware, the condition of the pulleys and cords, if the glass is original or replacement, and the condition of the surrounding jambs, stop and trim. Photography is important as it allows me to document details both of a window’s construction as well as particular problems such as broken tenons, checks and broken glass.

Once I have a handle on the condition I can make some educated decisions about how I will go about treating the window. Will it be a full restoration where I will remove the sashes and make the entire window look and function as it did when it was new? Will it be a conservation where I will arrest decay and make repairs as needed so that the window will remain as it is and retain original finishes and components. Or will it be a complete reproduction where I will use hand tools to make new window sashes that will match the originals? Once I have made these decisions I can consider whether and where I will use epoxy, which components will need to be replaced, and what sort of finishes I will use. It can be an involved project, but if incorrect decisions are made early in the process irreparable damage or unnecessary repairs can be made which will affect the historical integrity of a window.

In following blog posts we will look at the actual construction of a hand-made window sash modeled on the Stork House windows using period hand tools. I will explain some of the terminology I’ve used, such as scribed joints and coped joints, and demonstrate period construction techniques. Eventually we will look at window restoration and how we paint, putty and repair historic window systems. There’s lots to learn, so be sure to check back!

I want to thank Executive Director Kris Strobel of the Rockford Area Historical Society for giving me off-season access to the Stork House and allowing me to photograph and measure one of the windows. The Stork House is well worth the visit and one of the few post-and-beam houses in Minnesota. Its collection includes many family pieces and its hand-made millwork is fascinating. They have many events during the year so be sure to check their website.

Detail of the joinery of the meeting rails and stiles. Of interest is the ogee molding profile, parting bead, the tenon on the stile, the coped joint and wood pin. These details are crucial when restoring, conserving or reproducing an historic window.
Detail of a muntin and stile on the lower sash showing the scribed joint and ogee molding profile.

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