Window savings

Preglazed systems save time, money for manufacturers, installers, owners
Katy Devlin
July 22, 2008

Photo by Stephanie Chan, New York

Glass and glazing companies are facing tough times, as economists issue grim forecasts for the next year. The shortage of skilled labor, in addition to the pressures of constantly rising fuel costs and material prices make doing business even tougher.

Companies are working to rein in costs and increase productivity to combat the difficult construction environment through many means. One way is the growing use of preglazed window and curtain wall systems, allowing installers to close up building faster and with fewer workers.

While unitized curtain wall systems are relatively new to the market, many manufacturers have been producing commercial factory-glazed windows for decades.

Photo by Stephanie Chan, New York

15 Central ParkWest

Window manufacturer: Moduline Window Systems, Wausau, Wis., part of The Vistawall Group, Terrell, Texas, an Oldcastle Glass company.
Glazing contractor: Benson Global, New York

The systems: 37E fixed and project-in structural glazed casement ventilators and 67E Terrace Doors both with multipoint locking hardware. Factory glazed by Oldcastle Glass Moduline.

“Wausau has been making aluminum windows for 52 years,” says Doug Holmberg, general manager, Advantage by Wausau, for Wausau Window and Wall Systems, Wausau, Wis. “We started out making operable factory-glazed glass block ventilators and have progressed into other products where we have seen an industry need.”

Manufacturers say demand for preglazed systems has increased in the last five to ten years in part due to labor shortage issues and to owner demands for faster completion of large projects. Holmberg says sales for Wausau’s pre-glazed systems have increased more than 30 percent during the past eight years.

Fred Schoenfeldt, estimating marketing manager for Moduline Window Systems, Wausau, part of The Vistawall Group, says factory-glazed systems make up 60 percent to 70 percent of Moduline’s sales, versus 40 percent to 50 percent of sales a decade ago. “We are seeing this as an industry trend. There is more factory glazing of products now than there was in the past, because larger jobs can be closed up at a faster rate,” Schoenfeldt says.

Michael Brown, engineering manager for United States Aluminum, Waxahachie, Texas, agrees. “Industry wide, we’ve seen an increase in use of these products in the last five to 10 years. United States Aluminum has seen an increase in this type of activity within own business in last year or two,” he says.

Photo by United States Aluminum, Waxahachie, Texas

St. Mark Presbyterian Church, Newport Beach, Calif.

Window manufacturer: United States Aluminum, Waxahachie, Texas.
Glazing contractor: Nationwide Glass, Los Angeles
The systems: 115 units of series 7200 fixed windows, 80 units of series 7200 casement windows, 15 units of series 7200 awning windows, five units of series 7400 fixed windows, 67 units of series 7400 casement windows, 11 units of the series 7400 awning over fixed windows and series 3250 curtain wall. Windows factory glazed by Nationwide.

Lower labor costs

Factory-glazed systems for windows and curtain walls reduce labor costs on several levels. Mainly, preglazed window systems allow glaziers to close jobs faster and reduce the skilled labor required to complete the job, Holmberg says. “Compressed construction timelines make it appealing to the owners to make the building envelope weathertight as soon as possible. Factory-glazed products allow the installer to more quickly complete an area, which allows other trades to proceed with the interior finishes,” he says.

Additionally, “In certain regions, the limited availability and high cost of skilled field workers makes preglazed units a better value,” Holmberg says. Wages for employees in a factory setting are less than wages for glaziers on site. “Hourly labor costs to field-glaze window systems on-site are at least twice as expensive as the average hourly rates for a manufacturer’s staff to fabricate pre-glazed systems. For urban areas with high demand and higher rates, it can be up to four times as expensive for field labor,” Holmberg says.

Systems prefabricated by the manufacturer also free up labor strains on glazing project managers, says Bill John, president of Interclad, Minneapolis. “Outside fabrication and engineering frees up our internal resources to do more work,” John says. “There’s no glass to order, or metal takeoffs or cultists. The materials go directly to the jobsite.”

The man hours required to glaze a system are also less in a factory compared to a job site. Holmberg estimates on average a pre-glazed window system can be installed in half the time it takes to assemble and field-glaze a system on site. Schoenfeldt estimates the close up time is improved by 25 percent to 35 percent.

Brown attributes the time savings in large part to environmental controls. “The environmental control is probably the most important reason to do it in a shop. You don’t have to worry about delays due to rain, wind or dust. There aren’t delays like you run into in the field, so you don’t have to pull people off and on a project,” he says.


Photo by Wausau Window & Wall Systems, Wausau, Wis.
University of Notre Dame (Ind.), Farley Hall

Window manufacturer: Wausau Window & Wall Systems, Wausau, Wis.
Glazing contractor: Harmon Inc., Eden Prairie, Minn.
The systems: Historically styled Epic Series windows, part of the Advantage by Wausau line, with a beveled exterior face to replicate the glazing used on classic steel and wood windows. Factory glazed by Wausau.

Quality control

Along with environmental control comes quality control. Quality control becomes a major issue with factory glazed units, particularly when the manufacturer handles the preglazing, as the manufacturer has single-source responsibility. Quality control becomes easier with preglazed systems because the glazing is done in a clean and controlled setting and companies can test products before shipping them to the field.

“We can test the completed product for static air infiltration and water resistance to further confirm the quality and consistency of the materials and manufacturing methods,” Holmberg says. “This also reduces the owner’s risk if a problem develops later on, as there isn’t the question about who did what part of the work.”

In the factory

Manufacturers can preglaze in-house or ship the systems to contract glaziers to glaze prior to installation. United States Aluminum does not preglaze systems in its facility, Brown says.

Factory glazing does create challenges for manufacturers, Holmberg says, because companies need dependable glass suppliers, a factory setting with all necessary equipment, quality control measures, and a staff trained for handling glass and the glazing process.

“You need proper equipment and quality control to deal with … numerous configurations, differing sizes and the weight of the finished product,” Holmberg says. “It also requires that the window supplier have a variety of trailer types to allow the field staff to safely and efficiently get the delivered product to the openings.”

Wausau and Moduline both offer preglazing in their facilities.

“We have a department that does the glazing with individuals who specialize in running the silicone beads for dry glaze and wet glaze,” Schoenfeldt says. “Depending on the size of the system, they have access to silicone pumps to apply the cap bead—any structural glazing requires the silicone pump. And they have use of overhead cranes and power cups.”

Addressing size and strength

Manufacturers are increasingly faced with demands for larger systems. “The architectural community is calling for larger and larger windows and ventilators that typically require use of structural silicones. We have to make sure that the hardware and the product itself can handle the larger glass size or ventilator size,” Schoenfeldt says.

Building codes requiring protective glazing in more areas also has forced manufacturers to make stronger systems. Both size and strength demands heavier systems.

“We are seeing a market need for more robust hardware and glazing systems,” Holmberg says. “This requires a high level of engineering, product development and testing to meet these requirements.”

Window companies and glaziers need proper handling equipment to cope with the heavier loads. Systems prefabricated by the manufacturer, in particular, can create problems in loading and unloading. Because the preglazed windows are heavy and awkward to maneuver, unloading can be complicated if the windows are not packed in the correct order for installation, John says.

“On one job, six workers needed a full day to unload a truck, because they had to unload and restock the truck with the windows in order,” John says. “Another manufacturer worked with us to come up with a crating system. … Two workers unloaded that truck in two hours.”

Thinking green

A final benefit to preglazed windows is their green attributes, Holmberg says. “You eliminate the need to package and ship unglazed windows and glass,” he says. “Aside from the fuel to make separate shipments, you don’t have all the redundant glass packaging material. … Reduced packaging further contributes to savings for us as manufacturer and is reflected in our customers’ pricing.”

In addition, operable preglazed windows allow for natural ventilation and thus savings in a building’s heating, ventilation and air conditioning costs. The U.S. Green Building Council’s Leadership in Energy and Environmental Design program recognizes operable windows as an energy savings in a building.

Katy Devlin is editor for Glass Magazine. E-mail Katy at

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