ASBH Window Study Reveals a Cost-for-Quality Decision made by Wright and Richards

Frank Lloyd Wright’s American System-Built Homes were aptly named. Wright and his team had indeed created a “System” of architecture and construction designed to enable the “Building” of beautiful, high quality and still affordable homes. Nowhere is this more evident than in the geometries of the parts that would be used to construct one of the key features of the homes: their ample windows. Our window renovation project is revealing details of the design and making of these parts, including some kinks and quirks.

One of the main ingredients of Wright’s innovative System was a lumber yard that would pre-mill parts for construction in exact dimensions to allow for fast, high quality assembly on the job site. Evidence in the Elizabeth Murphy House (markings on trim, framing and cupboards) suggests that the yard milled the shapes, but shipped in bulk lengths for job-site carpenters to cut and fit while assembling the homes.

Like the homes themselves, which fell neatly into a part numbering scheme, pre-milled parts were numbered systematically, as shown on the section below. Note that milled pieces of cypress for the outside of a home were numbered starting with the letter A, whereas parts cut from a hardwood like birch for the inside trim were numbered starting with a letter B. Window sashes were not numbered, suggesting that they were preassembled and delivered for rapid installation.

Section Through Wall from Foundation to Top of Window. American System-Built (Ready-Cut) houses for The Richards Company, Floor Plan, Frank Lloyd Wright Foundation Archives: architectural drawings, ca. 1885–1959. The Frank Lloyd Wright Foundation Archives (The Museum of Modern Art | Avery Architectural & Fine Arts Library, Columbia University, New York) 1506.656

As we assembled the proper tools and processes to make Wright’s window sashes as Arthur Richard’s factory might have made them, we uncovered evidence of a decision to slow production in order to ensure quality, made a century ago.

Detective work sometimes requires the pursuit of a dead end until a better path emerges. Our first prototype was based on one of Wright’s drawings and was informed by the assumption of automation. By process of elimination, we were able to reduce the number of cuts necessary to create the tenons, mortices and slots to nine, all completed on machines (a planer, table saw and a mortiser*) and we were able to use the experience to estimate that we could prepare all the parts for one sash in about 2 hours. At first we were excited to find this efficient sequence – it seemed logical that a mill would want to make stiles and rails in batches on machines and avoid costly hand work. However, our prototype turned out to be an inexact replica based on conflicts between construction drawings and original windows.

As you can see from the image below, the tenon on the mock-up on the left (our first prototype) is in the position commonly used in sash construction, but is different than the tenon on the right. Wright’s drawings suggest both styles, but most homes seem to be built with windows that match our sample on the right. We suspect that tenon placement evolved as the System evolved, and the final tenon position was selected to allow for the greatest gluing surface (and therefore the highest strength.) However, this design requires a time-consuming tenth step; the reaming out of a blind waste piece using a hammer and chisel to allow the joint to mate (this is the space visible on the upper section of the sample on the right). Importantly, chiseling adds up to 20 minutes (20%) to the time to produce a basic sash (four cuts per sash), and introduces the real risk of human error. A laborer with a hammer and dulling chisel may slip or get tired, and parts might be scrapped. It seems that this was a cost that Wright and Richards were willing to bear to ensure long lasting casement sashes.

Not to scale. Testing samples only.

Incidentally, we are collaborating with our friends the stewards of the Oscar A. Johnson House – and with other stewards of ASBHs – on this window renovation project. We plan to invest almost 500 hours in the project for the Elizabeth Murphy House alone. We are documenting the similarities and differences in original parts and pieces between the homes to share with the Frank Lloyd Wright Building Conservancy and others, for posterity.

Here is the first of about 40 cypress sashes we plan to build together. (The sash behind Stuart and the table saw is a practice frame made from cedar. Building it helped confirm the steps, below.)

Stuart, steward of the Oscar A. Johnson House, holding a first ASBH replica window

This is our current build plan, accounting for handwork and installation and windows for two homes.

StepDescriptionTool(s)Time Estimate
(minutes per window)
1Plane raw stockPower planer10
2Layout pattern on raw stock (use templates to exclude knots) and cut stiles and rails to overall lengths leaving ¼” over length for tenons on railsMitre Saw5
3Cut rails and stiles to widths.Table Saw5
4Cut to rail lengths based on house. Key measure is ID which will determine overall width.Mitre Saw3
5Cut stiles to height of window being builtMitre Saw3
6Layout (using fixture) and make mortises, outside in.Mortiser (1/2″ bit)15
7Layout and cut tenon sides.Table saw with dado10
8Finish tenon widthPull saw5
9Mill slots (bead out) on both rails and stilesTable saw with dado10
10Chisel corner box on stiles to accept rail geometry below/aboveHammer/sharp chisel20
11Dry fit and plane tenon extra.Cross cut hand planer and sanding block10
12Dry fit into selected frame, mark, disassemble and cut mating sill angelsCircular saw on guides20
13Mark and chisel hinge boxesHammer/sharp chisel20
14Glue upClamps8
15Set glassClamps10
16Mitre and install beadsMitre saw20
18Mount Latches and Hooks20
Minutes per Window to Construct174.0
Minutes per Window to Install80.0
Total Minutes per Window254.0
Hours per Window21.2
Total hours (40 windows)846.7

You’re welcome to follow this blog to stay up to date on our forensic and preservation projects:

And experts in cabinetry, window-making, ASB Homes or Frank Lloyd Wright are welcome to weigh in with comments and advice below.

About this blog: The Elizabeth Murphy House is a 103 year-old American System-Built Home and the protagonist in the book “Frank Lloyd Wright’s Forgotten House.”

Note: *The mortising bit was invented in 1874 by the Greenlee Company in Rockford, IL, well in time for Arthur Richards’ mill to use it on ASBH windows.

7 thoughts on “ASBH Window Study Reveals a Cost-for-Quality Decision made by Wright and Richards

  1. Nice work ! As a cabinetmaker I am always interested to see how others perform their work; there seems always to be more than one method for many required operations. I am not aware of another Wright restoration woodworking project where there is a list of procedures, described and timed as you have done.

    I could offer one suggestion which should reduce the time necessary to mortise for hinges: make a simple router jig, and use a small router with a top-bearing end mill cutter, to easily make the bulk of the mortise in one step, requiring only a brief bit of chisel-work to square the two corners of the mortise. The time required to acquire the tooling and prepare the template ought to be paid for by the reduction of milling time from 20 minutes per window to five ?

    Keep up the good work ! Stephen

    1. Stephen, Thanks so much! Coincidently, I was just in my bits box inventorying router bits and found a mill cutter (from some project on another house years ago.) We’ll give it a shot and post pix!

  2. My pleasure, Nick.

    I’ve studied many Wright-studio and Taliesin construction drawings, as they have become available to laymen over a period of years, and I have been amazed and amused by the endless variety of solutions to what are usually routine detailing problems and millwork solutions. It is no exaggeration to suggest that with every new commission Mr Wright looked for fresh solutions to these repeated problems. The unique profiles which he devised and drew must number in the thousands. The architect apparently assumed that general or millwork contractors would be perfectly happy to have the necessary knives cut and set-ups accomplished to manufacture these parts and pieces—for a single unique house.

    The ASBH window and wall sections represent typical examples of this phenomenon. Here, where large-scale manufacturing was contemplated, such complexity is more understandable. I count four simple rectangles and seven unique profiles of varying complexity, in the drawing on this page. Someone disassembling an original ASBH house would be able to tell us how these parts were actually made—whether any of them were made on the table saw as opposed to the shaper or the multi-head milling machine. Surfaces produced by the saw are usually distinguishable from those made by one of the rotary milling devices.

    1. Stephen,

      Depending on the house, some of our ASBH co-stewards have parts and pieces stashed away from renovations and from other mistakes. For example, we removed a couple of window air conditioners and had to replace sections of frame and trim that had been ruined by drilling or chiseling. Many pieces have milling marks and a few have the notes (measurements and part numbers) from the yard workers. It’s amazing to find the same handwriting or machine scars on pieces of wood in houses hundreds of miles apart. So Wright’s idea to standardize the ASBHs is obvious, and I’m glad to have your perspective to explain why.

      I’ll make a note to photograph some of the parts and pieces and their markings and post here.

      Thanks again,


      PS: This is the profile labelled part number B9 in this image in the post.

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