More about Panelized Construction

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HUD’s new study, Panelized Wall Systems: Making the Connections, could move the building industry a bit further along the path toward better quality affordable housing. This thorough and well-presented report is perhaps the first comprehensive treatment of the connection systems used for the wall panels in panelized construction. The report is one of a series on different aspects of panelized wall construction from the Partnership for Advancing Technology in Housing (PATH).

Affordability and Quality

Panelized construction has the potential to make affordable housing more readily available, since factory-built panels perform well and are easily integrated into the building process. PATH envisions that, eventually, costs for labor, materials, and overhead will be lower for panels than for traditional stick-built construction. Although many materials presently used in panelized homes are more expensive than those in conventional homes, rising demand and the economies of scale should reduce costs over time. Currently, the price of this emerging technology is at least partly offset by labor cost savings because builders can employ fewer skilled laborers at the job site for shorter periods of time. A panelized house can be erected in a day, whereas a conventional frame house might take weeks or even months to build. Electrical wiring and plumbing pipes can even be built into the appropriate wall panel at the factory, reducing time spent by plumbers and electricians at the job site.

Panelized construction reduces the time required to erect a building and provides energy savings.

Panelized homes provide a superior barrier against moisture and temperature, an important aspect of housing quality. Because the components of these homes are designed and built at the factory and then shipped to a building site and erected immediately, waste and theft are reduced, raw materials are not exposed to the weather, and each component is precisely engineered for a tight fit. If panel connections are well handled at the building site, the result is a tight, durable envelope that translates into energy savings for the homeowner.

The Technology

To make the wall panels, core material is sandwiched between outer skins. The basic concept of a two-skinned builder’s panel is at least as old as the sheetrock traditionally used for interior walls. In recent years, however, manufacturers and builders have been applying this technology more broadly and imaginatively. No longer confined to load-bearing and partition walls, prefabricated panels are being used to design entire homes, including floors and roofs.

A PATH-commissioned survey of available panel systems in 2004 identified more than 110 systems that included skin materials of aluminum, concrete, expanded polystyrene, plastic, wood, brick and mortar, steel, and fiberglass. The core materials included agrifibers (from straw, wheat, or rice), autoclaved aerated concrete, polyurethane, Styrofoam, glass/wood, and various honeycombed materials.

Workers on the building site use connectors to attach the panels to each other and to anchor the walls to the floor and the roof. These connectors range from steel angles, screws, cam locks, metal plates, grout, and lumber and nails, to more sophisticated assemblies such as a metal track into which workers at the building site insert the bottom of a wall panel. Although manufacturing the panels under controlled factory conditions ensures that they will insulate effectively, the connections must also perform well to protect the structure’s interior from extreme temperatures, moisture, mold, and sound.

About the Report

The research concentrated on 12 of the most frequently used panel connection systems currently on the U.S. market for concrete panels (2 systems), metal panels (3 systems), wood structural insulated panels (4 systems), and wood open-wall panels (3 systems). Most of the report is devoted to matrices that, in straightforward, readable language, present general information, physical characteristics, performance characteristics, and performance criteria for each system. Color coding allows readers to scan a system’s features and make comparisons among systems.

This examination of connection systems will help builders identify appropriate options on the market today and integrate different panel structures. By documenting existing practice, this research sets a baseline against which the factory-built housing industry can continue improving panelized building systems.

Panelized Wall Systems: Making the Connections can be downloaded from HUD USER at no cost at www.huduser.org/publications/destech/path_panel.html or ordered for a small fee by calling 800.245.2691 and selecting option 1.