Mid-century tract homes and custom moderns can share the same flat roofs, beams and walls of glass, but they came from different processes. A tract house was one of many built from a set of plans by a merchant builder. A custom house was designed for one owner and one lot. Knowing which you're looking at changes how you research the house, how you judge its originality and which rules may apply when you want to change it.
Here is how Caltrans' statewide study of postwar tract housing, the National Register nominations for Eichler tracts and Palo Alto's Eichler guidelines describe the difference, and what it means for a buyer.
Three kinds of postwar builders
The Caltrans study sorts postwar builders into three groups by scale:
Custom house builders built only a few houses a year. They were the largest group by count but built a small share of postwar houses. Some worked at the high end, including unique, architect-designed modern residences.
Merchant builders, also called operative builders, bought large tracts of land, put in streets and utilities, built the houses and sold them as part of a new tract. This much smaller group built the great majority of California's postwar houses.
Community builders, a subset of merchant builders, added shopping centers, civic buildings and churches to their developments.
Joseph Eichler was a merchant builder. The study says he built tracts of houses only, a few with small parks and community centers. The Greenmeadow National Register nomination adds that by 1974 he had built nearly 11,000 tract houses and hundreds of custom homes, so even Eichler worked both sides. See our Joseph Eichler page.
How a modern tract was designed
Modern merchant builders hired architects, but the architect designed a set of plans, not one house.
Fees per design. Caltrans says Anshen & Allen charged builders a flat fee for each house design plus a royalty on each house built. Los Angeles architect Edward Fickett worked the same way and gave a builder up to six floor plans per tract, each with several design variations and paint colors.
Variety by arrangement. Fickett coordinated the variations and colors in each tract so identical houses weren't placed near each other. At Greenmeadow, the nomination says Eichler's designers used paper cutouts of the models to place each house where it fit the lot, oriented it as well as they could to the sun and protected neighbors' privacy. "In this way the architects made Eichler's houses feel like custom homes."
Choice at purchase. Greenmeadow buyers chose from several Jones & Emmons models and, for an extra cost, could request custom variations, usually to the interior. In San Jose's Fairglen Additions, one model, SJ-773, is described as a Palo Alto floor plan specifically requested by the original owner.
Scale set the limits. Caltrans notes that the Streng Brothers in Sacramento built 100 to 200 houses a year and could make minor plan adjustments for individual buyers, while builders producing hundreds or thousands a year sold a standardized product. Our Eichler floor plans page collects Eichler model plans.
Custom moderns, and the architects who did both
A custom modern started with one client. The Caltrans study's examples include William Wurster's one-story houses of the 1930s and Frank Lloyd Wright's Hanna House at Stanford, built in 1937. Many architects moved between custom and tract work:
Jones & Emmons. Caltrans says Eichler built about 5,000 houses from the firm's plans, and the firm also had commissions for custom houses, commercial buildings and high-rise apartments. See our Jones & Emmons page.
Cliff May designed numerous custom houses and, with architect Chris Choate, tract plans for merchant builders. Caltrans estimates that 18,000 tract Ranch houses were built from May's plans, not counting unauthorized copies.
Anshen & Allen designed tracts for Eichler and other Bay Area builders while running a broad practice that included service stations and commercial, government and religious buildings. See our Anshen & Allen page.
The label to watch is "custom home tract." Caltrans says some developers of more upscale tracts subdivided and sold lots instead of building every house, and marketed them as custom home tracts. In practice, the houses were typically chosen from the builders' stock plans rather than individually designed by architects. For Wurster's custom work, see our William Wurster page.
What the difference means for a buyer
Research. A tract house has relatives. Original sales brochures, model numbers and the recorded tract map tell you what the house started as, and similar houses nearby can show what yours looked like before changes. A custom house has one set of drawings, so the architect's name and archive matter more. UC Berkeley's Environmental Design Archives, for example, holds Eichler project records in its Claude Oakland and Kinji Imada collection, and the draft San Jose National Register documentation cites a 1960 drawing set for Fairglen model SJ-4 there signed by Oakland.
Historic value. Caltrans' guidance says the fundamental unit for postwar housing is the tract, not the individual house, and that tracts should normally be evaluated as possible historic districts. Only in rare cases will a merchant builder's tract house qualify individually under the National Register's design criterion. A custom house is judged on its own: Caltrans says an individual house must be an important example of its type, style or period, or the work of a master, and it must keep its integrity. Good condition alone isn't enough, and even for a tract, simply being the work of a master architect doesn't settle the question.
Rules. Tracts can carry rules as a group. Palo Alto's 2018 Eichler guidelines are voluntary, but the guidelines also describe the city's Single Story Overlay zoning over some Eichler tracts, which limits houses to one habitable floor. The two Palo Alto Eichler tracts listed on the National Register, Green Gables and Greenmeadow, both have that overlay, according to the 2018 guidelines. Zoning can change, so ask the city's planning department what applies to a specific parcel today, and check with an attorney if a deed restriction is involved.
Renovation. In a tract, a remodel is read against a street of related houses, which is why Palo Alto's guidelines talk about neighborhood cohesion. With a custom house, the question is how a change fits one designer's intent. Our Eichler renovation guide and mid-century modern design guidelines cover both situations.
How to tell which one you're looking at
Look at the neighbors. Caltrans notes that the houses in a postwar tract were usually built by one builder in a short period, and even in custom home tracts they tend to be similar in size, quality and level of detail. Repeated rooflines, siding and garage placements point to a tract.
Check the recorded tract. A tract number on the parcel and a builder's name in the original permits point to a merchant-built subdivision. A lone modern house on an older lot may be a custom design or an infill project by a small builder.
Match the plan. If the layout matches a published model, it's very likely a tract house, even if it was customized at purchase.
Ask for drawings. Owners of custom houses sometimes keep the architect's drawings, and the city may hold permit sets. For known architects, university archives are worth a search.
For more on how Eichlers relate to the broader modern style, see the difference between an Eichler and mid-century modern.
Frequently asked questions
Are Eichlers tract homes or custom homes?
Eichler's houses were primarily tract homes built from architect-designed models, though the Greenmeadow nomination says he also built hundreds of custom homes. Careful siting and buyer options made the tract houses feel custom, in the nomination's words.
Is a custom mid-century house automatically historic?
No. Caltrans' guidance says an individual house must be an important example of its type, style or period, or the work of a master, and keep its integrity. A well-preserved house isn't significant for that reason alone.
What is a "custom home tract"?
It is a subdivision where lots were sold for individual houses instead of the developer building every house. Caltrans says the houses in these tracts were typically chosen from builders' stock plans rather than individually designed by architects.
Can I find the original plans for a tract house?
Sometimes. Start with the model number, then look at sales brochures, the city's permit files and, for Eichlers, university archives. Our floor plan collections are another place to start.
Related reading
Eichler Architects: Who Designed Which Homes, Tract by Tract
Mackay Homes: What the Records Say About a Mid-Century Builder
Pricing an Architectural Home When the Comparables Don't Match
Weighing a tract modern against a one-of-a-kind custom house? Call or text the Boyenga Team at Compass at (408) 373-1660 or (650) 383-8606, or contact the Boyenga Team and we'll help you research both.
