US 3,760,548 · Granted 1973-09-25
The 1973 Interlocking Panel Patent That Made Building Modular
Imagine building walls like you're snapping together LEGO bricks. This patent describes a smart way to lock building panels together side-by-side using grooves and tongue-and-groove joints that slide together. It lets builders assemble insulated wall sections quickly without traditional nails or welds.
The plain-English version
What it protects
The claim covers a modular building panel system where each panel has a rigid insulating core sandwiched between front and rear sheets. What's protected here is the specific interlocking joint mechanism: one edge of each panel has recessed grooves with a protruding male tongue, while the opposite edge has a channel-shaped female receiver. When panels are placed side-by-side, these tongues slot into the channels of neighboring panels and lock into the grooves, creating a continuous interlocked wall assembly. The adjustable telescoping nature allows some vertical or lateral adjustment during installation.
Why it matters
Armco Steel's patent arrived during a surge in modular and prefabricated building technology in the early 1970s. By patenting this interlocking joint system, the company protected a manufacturing advantage that simplified panel assembly on job sites, reduced labor costs, and improved construction speed compared to traditional bolted or welded connections. The design also maintained structural rigidity while the panels were being connected, making it practical for large-scale commercial and industrial building projects where time and precision mattered.
Real-world use
You see this type of interlocking panel design in prefabricated metal wall systems, modular office buildings, and industrial storage structures where panels need to connect quickly and securely without visible fasteners.
Original USPTO abstract
A building panel construction made up of a plurality of interlocked side-by-side panels. Each panel comprises spaced, parallel front and rear sheets having therebetween an insulating, rigid core element bonded under pressure to the inside surface of the sheets. One edge of each panel is provided with a pair of spaced grooves having a recessed male member therebetween. The other edge of each panel is provided with an edge portion of reduced thickness and an end formed by a channel to form a female member into which a recessed male member of an adjoining panel may project, the outwardly projecting flanges of the channel being received by the spaced grooves on either side of the recessed male member of the adjoining panel.
Patent details
- Publication number
- US 3,760,548
- Filing date
- 1971-10-14
- Grant date
- 1973-09-25
- Assignee
- Armco Steel Corp
- Inventor(s)
- SAUER G,US, HELGESEN P,US
- CPC class
- E04C2/292
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