A Brief History
The design of the roof panels was somewhat controversial. Contemporary modernist architects faulted the pattern of the roof panels for imitating traditional clay tiles. One of the most critical was Carl Koch, an expert on prefabricatation, who Lustron hired in 1948 to improve the design and manufacturing process of the house. A decade later, Koch reported on his experience in his book At Home with Tomorrow:
Filled with confidence, we went after the roof design. . . . Roof panels had to fit tightly without gaskets, and the problem of making them weatherproof was even more serious. (During all the time we were in service, there was one engineer who sat quietly in a corner with this problem, trying out different shapes and sizes, drawing pictures, and muttering to himself.) We were mainly disturbed, however, that the roof panels were embossed to simulate Spanish tile. We thought it looked awful. But when we arrived with our packet of roof suggestions, we were told that, in the first place, the shape of the panels had been carefully calculated as the most economical use of steel plate in spanning the necessary distance. And that, in the second place, Lustron had several millions of dollars tied up in the machines that produced them, so the roof wasn’t going to be changed, and that was that.
In the company’s defense, the tile pattern was, indeed, functional: it stiffened the panels, which spanned a distance of four feet between roof trusses. To cross the same distance and be capable of sustaining snow and wind loads, a plain panel would have to be made of thicker steel. This would be more expensive and could have had structural ramifications-heavier roof trusses and beefier vertical supports. An alternative would have been to use more roof trusses, which also had economic and structural impacts.
The innovative gutter design met with more enthusiasm. It was applauded in a 1946 article in Better Enameling: “In the rain gutter design, beauty has been combined with utility. All gutters are extremely generous in size and fully porcelain enameled which, naturally eliminates rusting common to ordinary gutters. Here again is a typical example of how Lustron design assures extremely low maintenance.”
Roofs and Gutters: The Specs
Colors: Roofs and gutters of production models were only available in green
Panel Dimensions: 2 feet wide by 4 feet long
Number of Panels: 242
Gutter Dimensions: 4 inches by 4 inches
Materials: Light (20-gauge), structural-quality, flat rolled carbon steel
Connections and Fasteners: Overlapping edges of roof panels provide a watertight joint. Roof panels and gutters are fastened directly to the roof trusses with self-tapping, rust-resistant sheet-metal screws. Other components were bolted in place.
The Roof, Gutters and the Lustron System
The number of roof trusses varied by model. Each truss was made up of two half trusses which were bolted together with a center connector as seen below in EM-02-c-10.11.
According to a Lustron Corporation engineer the roof trusses were fairly beefy, “made up of one thousand of the basic structural section, three hundred twenty No. 02-502-12 gusset plates, two hundred seventy feet of 3/8″ round rod, standard bearing plate, and connectors,” all welded together. The trusses were spaced four feet apart. They were attached to the structure” by two bolts on each end and lateral bracing is made by two bolts per truss.” The Erection Manual has a number of drawings that explain connections between the trusses and walls, the installation of truss spacers, the location of wind bracing and wall tie-ins, and other roof details (see EM-02-C series).
After the trusses were in place, the gable ends were paneled The gutters were then attached to the roof trusses, with one 8-15″ x 5/8″ truss head slotted, tapping screw connecting near the end of each truss. Gutter sections had male and female ends, with a seal between. Most gutter sections were identical, but those on the ends were “right-handed” and “left-handed” illustrated below.
The side of the gutter facing the house had a high lip that interlocked with the bottom of the first row of roof panel. Installers started with the lowest roof panel on the left end of each slope and worked across horizontally, then returned to the left end and across horizontally for each of the next rows until they reached the ridge. Four “tiles” were on the standard roof panel. Above the gable ends, panels had a single “tile.” Depending on the dimensions of the house, the second tile from the left might have fewer than four tiles, as illustrated in EM-02-E-20.1 below.
The bottom, top, and sides of the roof panels had molded edges designed to fit the corresponding edge of the adjacent panel, forming a watertight seal. The roof was capped with ridge roll panels held in place by bolts with a cup washer and retainer. The number of panels used depended on the model number. Again, most of the panels were a standard size, but the ends had special “right” and “left” panels.
Once the roof was in place, the crew could begin work on the plenum and interior ceiling installation.