Patented Snap Fit Green Housing Technology

On March 19, 2013, the U.S. Patent and Trademark Office awarded a Patent for snap fit green housing technology, a flexible system of shelter construction using composite materials and natural fibers which includes five claims.

On December 10, 2013, the U.S. Patent and Trademark Office issued a Certificate of Correction identifying the inventors of the March 19, 2013, patent as Dr. Raymond Browning and W. Brandt Goldsworthy (deceased) and Lois Goldsworthy, legal representative.

These shelters are assembled on site from sections of snap-lock panels - flooring, wall and roofing - to form a complete housing, office, or storage unit. Shelters formed using the technology are strong, fast to assemble and are very protective from environmental extremes. The construction is frameless and needs only a footing or simple grading. The shelter system can be made completely livable with built-in utilities and pre-decorated surfaces.

Snap fit green housing technology is a refined method of housing construction that incorporates the advantages of composite materials with the pultrusion process for manufacturing the panels and the innovative snap-lock (fastenerless) joint system. Composite materials provide structural superiority, better thermal dynamics, no rotting and protection from pest problems. Snap-lock joints allow for easy assembly and structural integrity not found in conventional building methods and materials. Once construction is complete, structures are suitable for emergency dwellings, factory tilt-ups and high quality custom housing.

The world of fiber composites makes snap fit green housing technology an attractice alternative to composite applications by glass fiber-reinforced plastics and by carbon fiber composites. The natural fibers include wood fiber, flax, hemp, abaca and many others. Current natural fiber composite products are either extruded or pressed and it is therefore possible to adapt them to pultrusion.

The recent shift upward in petroleum costs favors natural fiber composites as they are only 50% thermoplastic and therefore less sensitive to price increases. There is ample evidence that natural fibers could be used as a direct replacement for glass fiber in the snap fit green housing technology by straightforward modifications of the current pultrusion techniques. This opens the possibility of significant cost reductions in raw materials and the transfer of production operations to areas of the world where manufacturing labor costs would be lower.

We envision opportunities in hybrids of glass and natural fibers, or the use of natural fiber, as the core of a structural sandwich surrounded by glass fiber composite in snap fit green housing fabrication technology.


The present application is a continuation of U.S. Utility patent application Ser. No. 11/547,882, filed Oct. 4, 2006 which application was submitted under 35 U.S.C. 371 based on PCT/US2005/11859, filed Apr. 8, 2005 which, in turn, claims the benefit of U.S. Provisional Patent Application Ser. No. 60/561,001, filed Apr. 8, 2004 and further claims the benefit of U.S. Provisional Patent Application Ser. No. 60/577,435 filed Jun. 4, 2004 each of which application is incorporated in its entirety by reference herein.

The March 19, 2013, United States Patent 8,397,461 resulted from utility patent application No. 11/547,882, filed October 4, 2006, for an invention that relates generally to structural materials, and more particularly to prefabricated structural members, and still more particularly to snap fit pultrusion housing elements for joining structurally insulated panels suitable for housing and shelter construction. A December 10, 2013, Certificate of Correction lists the inventorship in Dr. Raymond Browning and W. Brandt Goldsworthy (deceased) and Lois Goldsworthy, legal representative.

The Basic Pultrusion Process

The pultrusion process invented by W. Brandt Goldsworthy in the 1950s is an efficient means of pulling fiber reinforcements through a bath of polyester resin to create lineals, in this case housing panels. Pre-measured, indexed and identified parts are made of commodity materials and are ready for assembly on site.

The Pultrusion Process


Snap fit housing technology can be packaged in a shipping container, making it suitable for delivery by flat bed truck or air-drop to remote sites. The housing technology needs only minor training to assemble and immediately forms strong structural elements that are safe and protective to work within. The housing technology can include a variety of materials - insulating, lightweight, impact proof - that are enrobed in the composite pultrusion fittings that make up the core of the innovative technology.

Two Functional Parts

Housing parts are limited only by the size of the pultrusion machine and can be used to make multiple layers with cores made of urethanes, phenolythics, balsa, or Kevlar. Truck and train refrigeration cars using this design have been in use a number of years and the results have been exceptional. There are favorable comparisons in cost, corrosion elimination, thermal integrity, major weight reduction, durability and design flexibility.

Snap fit housing technology has two functional parts, the snap lock fitting and the panel body or housing section. Both these parts are formed together in the pultrusion process. There are a variety of different fittings and panels for different uses. To form a larger panel for a floor or wall, a filler such as a flat 10'x20'x4" section of polyurethane foam, balsa, or material is pultruded through a machine which lays down a glass fiber skin, top and bottom, on the filler while at the same time pultrusing the snap-lock fitting on the edges of the panel - the fitting would attach a wall to a floor section, for example, the wall panel having a tongue that slips into a groove in the floor fitting. The wall then rotates around the pivot point and snaps into place in an upright position. The radius of the fitting is such that the inner decorated surfaces of the wall and floor do not mar as they mate and also form a watertight seal with the addition of a small mastic bead along the guide surfaces.

The two outer skins are formed of a glass phenol matrix and a foam center made of polyurethane. The snap fit locks in place and is a very strong joint giving a free standing wall. The same joint can be modified to work in the opposite direction of locking for two floor to floor panels or roof to roof. Variations on the snap-lock design give a full range of fittings to enable the construction of a complete shelter. The hollow sections of the snap fit extrusions can be used as conduits for electricity, gas, and water utilities thoughout the complete snap fit composite housing structure. Each housing section can be provided at the time of manufacture with an integrated utility supply appropriate to its housing function. For example power outlets can be integrated into the interior sides of the walls and the snap fit extrusions used as conduits for cables with plugs to mate with other sections.

The range of potential applications includes emergency housing and storage spaces in extreme climates. The weight and costs for these applications is very competitive.