WW2 Era Mass-Produced Housing (Part 2)
Welcome to Construction Physics, a newsletter about the forces shaping the construction industry.
Below is part 2 of our look at WWII and post-WWII housing mass production. For Part I, see here.
The California Method
In 1940, California was the fifth largest state in the US, tied with Ohio at 6.9 million people. Over the next 30 years, thanks in part to enormous spending on military facilities and wartime factories , it’s population would nearly triple to just under 20 million. It would surpass New York as the most populous state in 1962.
This growth was fueled by the construction of enormous housing developments - 3,000 houses were built at the San Lorenzo development between 1944 and 1952. 6,000 houses were built at Westlake. 3,000 homes in Panorama City, another 3000 in North Highlands, and another 3,000 in Linda Vista. And between 1950 and 1953, over 17,000 homes in Lakewood. By 1949, large merchant builders (builders who built 100 houses a year or more) accounted for 80% of new houses, and 45% of housing was built by just the top 4% of builders.
To build houses at the speed required, many of the California builders adopted mass production techniques. Despite the achievements of Levitt with Levittown, the assembly-line method of constructing large housing tracts  became known as the California Method. A 1949 article in Fortune describes the typical process, as it was used at San Lorenzo:
Briefly, the California Method means setting up a complete mobile production line…(At the cutting yard) the raw lumber, usually in large sizes, was started along a series of roller tracks through the power saws and planers that transformed it into studs, joists, bridging, rafters - more than 9.5 billion board feet for the job. Since only two floor plans were used at San Lorenzo, there was little resetting of the saws and a minimum of time-consuming handling of lumber.
As a piece of lumber passed each saw, the next cut on it was indicated. When it reached the end of the line, ready to go into the house, the piece was keyed for it’s exact position. A roof rafter, for example, passed through four saws in its transformation from a length of two-by-four, and seven men turned out 700 of them an hour. As each structural element of a house was finished, it was placed in a pile with other elements that went to make up a single dwelling unit. The result was that, in full operation, the cutting yard resembled a vast lumber filing cabinet of houses to be built.
Doors, frames, windows, kitchen cabinets, anything else that required mitering, were cut and joined on jig tables two at a time and finished by shop painting. Even foundations were susceptible of production-line methods. A template was set down by a surveyors’ stake, walls and piers were marked on the ground, a ditching machine dug the trench, and portable wall and pier forms were put in place. Then the concrete was brought from a central mixer and poured. With fifty sets of portable forms, Bohannon got in twenty-five foundations a day.
A critical element of the California Method was a temporary sawmill for pre-cutting lumber. Lumber would be cut in the exact quantity and size necessary, bundled, and delivered to each housing lot. By decoupling the cutting step from the critical path, construction times could be dramatically shortened - at San Lorenzo, the first 633 units were completed at a rate of 1 every 45 minutes.
California Method housing developments (as well as Levittowns) went beyond just tracts of houses - entire communities sprung up in previously unoccupied land which had been made accessible by increasing automobile adoption . In addition to homes, large merchant builders would build roads, parks, schools, and shopping centers. The “Community Builders’ Handbook”, first published in 1947 and authored by some of the country’s large builders, advises the developer on everything from recommended distance to police and fire services, to optimal housing density, to street layout, to sizing shopping centers.
One of these communities was Lakewood, one of the largest and fastest housing developments of the postwar period - over 17,000 houses built in just 3 years. Built on 3450 acres of former sugar beet farm 10 miles south of Los Angeles, between 1950 and 1953 Lakewood grew from just a few houses to a community of over 70,000 . It contained 133 miles of streets, 266 miles of sidewalk, 21 shopping centers, 12 churches, 10 schools, and one of the largest shopping malls in the US.
Building Lakewood pushed construction division of labor to the absolute limit. Houses were built step by step using 30 separate crews, each with a separate job - one crew would be dedicated to installing subfloors, another rafters, another sheathing, another garage doors. Each task was allocated a particular number of hours to complete.
One of the largest time sinks in craft production - and one of the places factory production gets its efficiency - is the time it takes to set up for the next task. Consider a carpenter building a wall. If he’s working by himself, he might first measure a piece of sheathing, then cut it to length, then carry it to where it needs to be installed (after turning off and stowing the saw), then grab nails and a hammer, find someone to help him hold the board into position, and nail it into place. Each time he switches tasks, there’s a delay between stopping the previous one, and getting the next one arranged. Each setup takes time .
On the other hand, if the sheathing is precut and brought to the jobsite, and a steady supply of nails is provided and helping hands is provided, he can just keep nailing sheathing. He’ll never be interrupted by running out of sheathing, or waiting while someone else uses the saw, or for someone to hold it for him, or deciding what to do next. Assembly line type work minimizes setup time:
We found from experience that the fewer things a man has to do, the quicker he can do them. These men know what they have to do and they can do it blindfolded. They get it right. They never have to stop and scratch their heads. It’s all been worked out for them.
Minimizing setup time didn’t stop at division of labor. The entire 4000-man crew worked by a carefully orchestrated schedule. Allocation of equipment, materials, and labor was planned months in advance. Lakewood was built on a large, rectangular grid, and crews moved up one street and down the other to minimize travel time between tasks.
Completion of a house at Lakewood took 45 days. At its peak, 100 houses a day were being finished, one of the fastest rates of construction ever in the US .
Lakewood had no architect involved in the design, merely a team of drafters whose work was occasionally adjusted based on “market feedback”. And though it included 15 different houseplans, it didn’t escape the criticisms of being full of repetitive, mass-produced houses (much like Levittown).
Comparing to Modern Construction
How do the rates and scale of housing construction in the late 40s/early 50s compare to today?
We can see the average rates of production are impressive, ranging just over 5 to over 50 houses built per day. Peak production rates were even higher.
By comparison, in 2017 Clayton Homes, the largest manufactured home builder in the US (and the closest thing we have to industrialized construction) built an average of just over 3 homes per day at each of their 40 factory locations. Traditional construction is even less impressive - the average construction time for a home built for sale is 6.1 months. If we assume a 121 house subdivision (the average in the US for new SFH development projects in 2016), we get just over 0.6 houses per day - 5x slower than a manufactured home factory, and around 100x slower than peak postwar production rates.
So why did we stop building like this?
Despite its speed, and it’s popularity in markets like California, this type of rapid, large scale housing production never truly became the norm. In 1969 (right before housing production peaked), only 8.1% of new housing units were built by builders of 500 or more units per year.
Housing mass production was about building homes as fast as possible, to satisfy a large, pent up demand caused by years of underbuilding. Once that demand was satisfied - once the people stopped lining up for a chance to buy a new house, and started to want more variety in their homes - the impetus for rapid, large scale housing construction was no longer there. Levitt and Sons remained in business up through 2007, but didn’t build any more Levittowns.
Construction at mass production scale is extremely capital intensive. Builders like Levitt and Bohanon made huge investments in equipment and facilities (sometimes going so far as to buy whole forests). Without mass-production levels of production, this type of expenditure is impossible to justify (as many prefab construction startups find out).
Even at the time, the capital requirements had a major effect on profitability. Bohanon allegedly saved 30% on construction costs by using a reverse assembly line, but much of that was consumed by additional equipment costs and overhead costs. Levitt boasted that he could “under price the competition by 1500 dollars and still make 1000 dollar per house”, which would be a cost savings against traditional methods on the order of 20-30%. Impressive, to be sure, nothing in the realm of the savings from true mass production.
And outside of reverse assembly lines, many of the labor-saving innovations of the mass builders did make their way into traditional construction. Much of the time savings came from things like standard sized sheets of plywood, using drywall instead of lathe and plaster, pre-assembled roof trusses, and power tools - all things which are now standard in residential construction.
 - California was first in the nation in contracts for shipbuilding, aircraft production, and expansion of military facilities during the war. San Francisco and Los Angeles were the largest shipbuilding and aircraft manufacturing areas in the US, respectively. By 1945, Los Angeles was second only to Detroit in industrial production.
 - Builders like Henry Doelger had been experimenting with mass production methods for years for years:
During his busiest years in the Sunset, Doelger used practices that would become common in mass home building in the next decade. Because he built largely standardized houses for speculative sale, Doelger took advantage of economies of scale by purchasing materials in bulk. His scale of production made it cost efficient to operate his own lumber processing mill near his building sites where crews precut materials and selectively preassembled elements of each house. A dedicated millwork operation also completed all interior and exterior architectural trim, ranging from door moldings to flower boxes. Doelger’s workers then bundled the materials into “kits,” which they delivered to each building site. Doelger organized his labor force based on assembly line principles as well, separating his workmen into crews who specialized in one specific part of the home building process such as foundations, framing, sheet rocking, and finishing. In addition to efficient planning and work patterns, Doelger began experimenting with ways to use and pay for labor more efficiently or cheaply. He kept a skeleton crew of workers building almost constantly, which prevented him from having to hire workers less familiar with his units from union halls. The firm selectively subcontracted out plumbing, electrical, tiling, and stucco, sometimes employing two competing bidders at the same time and promising incentives to the fastest crews. Doelger also hired lesser skilled labor to do single, repeated jobs on each house as a way of saving on labor. With these practices in place, Doelger Homes was building as many as two houses a day in the Sunset by 1939.
 - Previously development had largely been limited to areas accessible by train or streetcar, resulting in “starfish” patterns of development around major metros. As automobile adoption increased, previously empty areas between the starfish arms would fill in.
 - 70,000 is larger than the current-day populations of Cheyenne Wyoming, Portland Maine, or Burlington, Vermont.
 - Reducing setup times is a key aspect of the Toyota Production System: When Toyota engineers examined the change-over, they discovered that the established procedure was to stop the line, let down the dies by an overhead crane, position the dies in the machine by human eyesight, and then adjust their position with crowbars while making individual test stampings. The existing process took from twelve hours to almost three days to complete...Over time they reduced these changeover times from hours to fifteen minutes by the 1960s, three minutes by the 1970s and then just 180 seconds by 1990s.
 - This was the theoretical capacity of the Lustron factory as well, another massive initiative unlikely to be duplicated.