Static structures (e.g. – buildings) – Preassembled subenclosure or substructure section of unit or... – Collapsible for ease of transport
Reexamination Certificate
2001-09-04
2003-11-25
Friedman, Carl D. (Department: 3635)
Static structures (e.g., buildings)
Preassembled subenclosure or substructure section of unit or...
Collapsible for ease of transport
C052S079100, C052S079200, C052S079120, C052S079700, C052S079900, C052S124200, C052S270000, C052S262000, C052S266000, C052S236300, C052S234000
Reexamination Certificate
active
06651393
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to the modular construction industry, and relates more specifically to a construction system for manufactured housing units, which units can form multi-story structures at a building site.
2. Description of Related Art
The conventional building construction art for years has recognized the cost and efficiency advantages of having construction in most part completed at the manufacturing plant, as opposed to significant construction on-site. “Manufactured housing” as used herein means a virtually complete and finished housing unit, wherein a significant portion of the construction of the unit is completed at the manufacturing plant. In current construction techniques, manufactured housing includes, for example, mobile homes that are built in most part at the factory. The interior partitions, doors, fixtures, equipment, windows, among others, are installed in the mobile home before it leaves the plant. Manufactured housing thus is not meant to include simply modular core constructions with little to no finishing that are shipped to a construction site for finishing and integration into a building structure.
Manufactured housing fills a tremendous need for affordable, single-family housing in rural areas of the country. In fact, manufactured housing accounts for approximately one-third of the total housing starts over the last several years.
Specific advantages and limitations of prior art building construction techniques follows. A first set of points outlines many advantages of manufactured housing, vis-à-vis on-site construction. Conversely, a second set of points illustrates construction applications where onsite construction is preferred over manufactured housing techniques. Typically, a building structure comprises only one of these two types of construction techniques; they are often mutually exclusive. For example, multi-story structures comprises almost exclusively of on-site construction elements. While it is undisputed that costs would be lower and construction efficiencies increased if multi-story structures could comprise in significant portions manufactured housing, the current state of the manufactured housing art does not enable such construction.
Thus, a third set of points are discussed that particularly identify the current limitations and roadblocks of utilizing manufactured housing units in a multi-story structure, as opposed to simply cornering manufactured housing techniques for only single-story modular structures. It is the specific prior art deficiencies of this third set that the present invention primarily addresses and overcomes, such that multi-story structures can indeed comprise in significant portions manufactured housing.
A. Benefits of Manufactured Housing
Manufactured housing as embodied in, for example, the present manufacture of mobile homes offers several advantages over site-built housing construction. In the factory environment:
Construction can occur year round, regardless of the weather.
Production in the factory with the use of jigs and assembly line techniques leads to a more uniform product under quality control supervision.
Assembly line efficiencies enable one man to do more than one task.
Completion time for construction is reduced.
Typical factory wages are substantially less than field wages.
Units are almost fully pre-finished in the factory, so that interior partitions, doors, fixtures, equipment and windows, among others, are installed in the units at the factory.
Site setup requirements are reduced since the modules are shipped with most of siding, roofing and interior finishes complete.
It is clear from the above non-inclusive list of advantages that generally the more construction carried out at the manufacturing floor, the better. Yet, present manufactured housing has its limitations.
B. Benefits of On-Site Construction
Site-built construction conventionally is preferred over manufactured housing for multistory structures. Several reasons for this include:
Flexibility in design without being restricted to the use of “rectangular” rooms or sections.
Compliance with current building and life-safety codes that typically require the use of materials such as concrete and steel that are stronger and less flammable than wood, and thus more expensive and time consuming to ship to the site as complete.
The perception that manufactured housing as it relates to multi-story structures is simply “stack-a-shack” construction.
C. Limitations of Manufactured Housing with Multi-Story Structures
It is known only in some very specific and limited applications to use manufactured housing elements in a multi-story structure. Yet only a very few of the advantages attributable to manufactured housing reside in these limited applications:
Each manufactured housing unit is typically built with a separate floor and ceiling. Thus, when stacking units one atop another at the site, the floor on an upper unit is set upon the ceiling of a lower unit. This results in a redundant doubling of the number of structural joist members. This is unlike conventional on-site construction that uses the same joist members for both the upper floor and the lower ceiling between two modules.
According to most building and life-safety codes, it is prohibited from building wood structures over three stories in height. For a building to have more than three stories, steel or concrete structural members typically must be used. This additional building height requires supporting structural members in a diversity of sizes. For example, the lower floors typically require wider vertical members with varying spacing. Concerns about the weight, shear, and wind loads as more floors are added put even greater emphasis on the positioning of the exterior load bearing walls, thus reducing the flexibility in floor plan design.
The use of concrete for a manufactured housing unit's walls and floors necessitates time-consuming form preparation with more complicated handling considerations. Typically, the units are smaller, thus requiring several units per floor in a building. This increases transportation costs along with the need for more material per floor.
Steel is easier than concrete to use in a manufacturing plant. The art is well developed in the use of steel for building multi-story structures. However, the typical assembly techniques utilizing steel have limited the amount of the manufactured housing unit's interior and exterior finish that can be completed in the factory. For example, the art has heretofore relied heavily on welding to connect most of the structural steel elements that are required in a multi-story building. Welding units together on-site is very cumbersome and can generate heat and sparks that can easily damage any factory-constructed interior or exterior finish that is near the joint to be welded. Thus, truly finished manufactured housing units cannot be used in such building techniques.
A major portion of the construction of a modular-built, multi-level structure still is completed at the site. Most of the exterior finish is not completed until the manufactured housing units are set because of the access required by men and machine to attach the units together, both horizontally and vertically, which access would destroy a factory-constructed exterior finish.
Multi-story modular buildings are typically erected by first setting the manufactured housing units in place both horizontally and vertically, and then building and attaching connecting breezeways, corridors and stairs. This progression of setting the units first prior to breezeways, corridors and stairs) creates its own four distinct problems.
(1) The more units that are used (especially the higher the units are stacked), the more difficult it is to keep each subsequently higher unit level and plumb.
(2) For buildings exceeding two floors, it is very difficult to maneuver each unit into place at the site. Although a crane can come close to setting a module fairly accurately on top of another module,
Don Lawrence C.
Lissiak Victor
Friedman Carl D.
Lorwood Properties, Inc.
Schneider, Esq. Ryan A.
Troutman Sanders LLP
Varner Steve
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