Where the warm floor started.

By January 1950 Eichler had four modern developments behind him. Stanford Gardens was the fifth, about a dozen houses on Evergreen, Oakdell and Lemon Streets, east of Stanford Avenue. They sold for roughly $19,500 and had two and a half bathrooms, which was generous for a tract house of that year.

The plans came from a draftsman recorded in the histories only as Castor — no first name survives. This is before Anshen & Allen, before Jones & Emmons, before any of the architecture that made the name. What was already there was the intent: glass, an open plan, and an unbroken ceiling.

It is worth being plain about the significance. There are only four Eichler developments older than this one, and Menlo Park has this one.

The best surviving primary document for this tract is a sales advertisement. It ran in the San Francisco Chronicle on 16 April 1950, in the World of Leisure section, page 5, under the headline “Of course It’s an Eichler Home!”

The copy calls the houses “boldly imaginative in design, dramatic in its use of redwood, brick, glass, and color.” It lists radiant heat, three bedrooms, two and a half bathrooms, a two-car garage, and roughly 1,650 square feet. The furnishings in the model were by the interior designer Nancy Porter.

The price in that advertisement is $21,000. Eichler Network gives the tract’s price as $19,500. We have not been able to reconcile those two figures and we are not going to quietly pick the one we like — the likeliest explanation is that they are different models, or an opening price and a later one, but that is inference and we will label it as such.

The same ambiguity sits on the date. Eichler Network says the tract opened in 1949 in one article and completed in January 1950 in another. For a tract this early in the company’s life the distinction matters, because it changes where these houses sit in the sequence of Eichler’s work. Both readings are in print and we cite both.

Stanford Gardens was where Eichler first ran hot water through pipes buried in the concrete slab. Every Eichler after it inherited the idea.

It is not a comfort feature; it is what lets the architecture work. With no radiators and no floor registers there is nothing interrupting the glass wall, nothing breaking the ceiling plane, and no ductwork demanding a dropped soffit. The open, uninterrupted room that people buy these houses for exists because the heating went into the floor.

Seventy-five years on, that same decision is the largest single risk in an early Eichler. The original pipe was steel, and steel in concrete has a finite life. A failed loop is expensive and disruptive, and the difference in value between a house with a documented modern repipe and one still on original pipe is real and specific. It is the first thing we check here, and the first thing a well-advised buyer asks.

We sold 675 Evergreen Street, which is one of about a dozen houses in this tract. The photographs on this page are that house.

It shows the type well: a low roof over a wide plan, the street given a front door and very little else, and the whole budget of the elevation spent on the garden side. Inside, the beams run unbroken from the ridge out past the glass, the fireplace is the only solid mass in the room, and there is not a radiator or a floor register anywhere — which is the 1950 decision this tract is famous for, still doing its job.

The slab and the loop, first: whether the radiant has been repiped, when, with what, and whether there is paperwork. An owner with documentation is holding money.

Then how much of the original house survives. On a 1950 Eichler the details that matter are the ceiling line, the glazing, the position of the kitchen and whether the plan has been closed in. Early Eichlers are small by modern standards, which historically made them targets for the kind of remodel that removes exactly what a buyer now pays a premium for.

And the lot. Corner lots in this neighbourhood sit outside the protections that apply to the standard lots around them — which is how one of these came down in 2013.