US 3,714,747 · Granted 1973-02-06

The Hidden Clip That Made Seamless Wall Panels Possible

Imagine a wall panel made of foam sandwiched between two tough skins, but with zero visible bolts or screws on the outside. This 1973 patent invented a hidden clip system that locks the panel edges together from the inside, so the wall looks perfectly clean and finished from the street side.

Curated and verified by the IsItPatented Editorial team

The plain-English version

What it protects

The claim covers a fastening system for double-layer foam core building panels where a metal clip and fastener mechanism attaches the inner edge segment of the panel to the structural framework without creating any visible holes or fasteners on the exterior surface. What's protected is the specific way these components interlock and remain hidden within the panel's design.

Why it matters

This patent solved a real construction problem: how to assemble prefabricated foam panels quickly and cleanly without leaving ugly bolt holes or requiring complex on-site fastening. By hiding the mechanics, builders could create seamless exterior walls that looked polished right off the assembly line, making foam core panels more attractive to homeowners and developers.

Real-world use

When you see a modern mobile home or prefab building with smooth exterior walls and no visible seams or fasteners, you're likely looking at construction that evolved from this hidden-clip concept.

Original USPTO abstract

A DOUBLE-SKIN FOAM CORE BUILDING PANEL PRESENTING AN INBOARD SIDE SEGMENT ALONG ONE SIDE AND AN OUTBOARD SLIDE SEGMENT ALONG ITS OPPOSITE SIDE-THE SIDE SEGMENTS BEING ADAPTED TO BE ASSEMBLED IN LAPPED INTERFITTED RELATION WITHOUT EXTERNALLY VISIBLE FASTENERS. HIDDEN FASTENING MEANS IN THE FORM OF A CLIP AND FASTENER IS PROVIDED FOR SECURING THE INBOARD SIDE SEGMENT OF THE PANEL TO THE SUBGIRT OF A STRUCTURAL FRAMEWORK. D R A W I N G

Patent details

Publication number: US 3,714,747
Filing date: 1971-08-23
Grant date: 1973-02-06
Assignee: Robertson Co H H
Inventor(s): CURRAN B,US
CPC class: E04F13/0837

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