Superlite Energizes Block Wall Market
By: Bill Blaha
Oldcastle's Arizona concrete masonry unit enjoys growing success with its energy-efficient Integra System.
Concrete block, once the dominant building material for new housing in Phoenix, Arizona, but now a second choice behind wood frame construction, is making a strong bid to win back buyer preference through an energy efficient post-tensioned masonry wall system developed by Superlite Block.
So far more than 8,000 homes have been built in the Phoenix and Tucson areas using the company's patented Integra Wall System. What's more, the system recently won building code approval for loadbearing applications and is also being aggressively marketed for commercial and industrial structures.
Integra is an engineered wall system in which the cavities of specially designed H-shaped block are filled with polyurethane foam insulation to provide a tight seal against heat and cold. Inside the wall system, vertical steel reinforcing rods connected to the foundation and running to full wall height are post-tensioned. Tensioning the wall in this manner reportedly allows for a more efficient use of the insulation.
The result is a monolithic wall system that, in addition to providing all the benefits of conventional block construction, has an energy-saving R-value of 16 to 27, depending on the type of unit used, and is stronger than most residential wall requirements.
The Integra system is being promoted as a cost-competitive alternative to wood framing, said Edward Freyermuth, technical services manager for Superlite and one who played an important role in bringing Integra to the marketplace.
At one time, block was the favorite choice among Phoenix homebuilders, he pointed out. However, starting in the late 70's wood frame became more popular as builders from other parts of the country moved to the rapidly growing Southwestern city and brought their old building habits along with them. But that is changing. The increasing cost and growing shortage of lumber is pushing up the price of new homes. Last year, rising lumber prices added $3,000 to $4,000 per house in the Phoenix and Tucson area. This is forcing the builders to look at other materials and construction methods, like the innovative Integra system, to try and keep housing affordable.
According to Freyermuth, the price per square foot of a typical home built in Phoenix or Tucson using the Integra system is roughly the same as one built of two-by-six wood frame. Moreover, besides providing the standard advantages of block construction - durability, resistance to sound, fire and termites - Integra offers much greater energy savings.
Research sponsored by Superlite indicates that a typical wood frame house uses 11.9 percent more heating and cooling than an Integra-built home. For Integra system homeowners, this adds up to a month and a half (43 days) of free heating and cooling each year.
To make people more aware of Integra, Superlite is conducting a vigorous marketing program. This effort, backed up with television, radio, magazine and billboard advertising, as well as personal calls on architects and builders, is proving to be increasingly successful for the Phoenix-based company, which ranks as the largest block manufacturer in the state and with an annual production of 25-30 million units is among the five top suppliers in the nation.
Thus far some 50 builders in Phoenix and Tucson have made use of the system, some of whom are continuing to do so on an exclusive basis. They range in size from small outfits to among the biggest developers in the state. Similarly, their Integra-built homes vary from modest entry-level dwellings to 15,000 sq. ft. luxury homes selling for more than $500,000. Superlite's role in the construction of an Integra wall goes way beyond furnishing of block. To maintain a necessary level of quality control over the system, company personnel are responsible for placing the polyurethane insulation and doing the post-tensioning. Also, the company supplies the reinforcement rods and all internal steel components needed to complete the post-tensioning work. In effect, Superlite acts as an on-site subcontractor for the project.
Block required for the Integra Wall System are made at three company plants in Phoenix and another in Tucson. The type of block most often used for this purpose is a 6x8x16-in. H-shaped unit that is open at both ends and has a reduced center web to minimize thermal bridging. Other block, however, are available for Integra walls in a variety of designs and textures.
The blocks are delivered to the job together with the post-tensioning rods. Made of high tensile steel, the 7/16th inch diameter rods are roll threaded at each end. They are attacted to special anchor bolts and fitted with a 1 3/4th inch long coupler that is placed in the structure's poured concrete or masonry foundation.
The rods are nominally spaced every 4 ft., except where there are door and window openings. In most cases a single rod will extend the full height of the wall. However, for taller walls such as those built for commercial and industrial structures, multiple sections are installed.
Integra system walls are laid up in a running bond pattern with Type S mortar applied to the block's head and bed joints. A plate bearing block is then placed on the final course at each tension rod location.
Superlite monitors the progress of each job so that a post-tensioning crew can be scheduled to go to the site once the mason contractor has finished laying up the walls. To make sure things run smoothly, the company keeps three two-man crews out in the field. Working under the direction of Dave Endres, each crew has a van body truck containing all the equipment needed to carry out its work. Among a truck's contents, for example, are tool boxes for steel and assorted components, a generator and two tanks with enough liquid polyurethane to insulate the walls of four average-size homes.
As soon as a crew arrives, normally the day after the block work is finished, the walls are tensioned atop each plate bearing utilizing a kit of components that includes a Direct Tension Indicator washer, hardened washers and a half-inch steel plate. The rods are tightened until the DTI washer is compressed to an initial load of 7,400 lb. of tension.
Next, polyurethane insulation is pumped from the top of the wall into the block cavities. The specially formulated insulation quickly expands and hardens to more than 30 times its original volume, effectively sealing all pores and voids in the block. After the walls are completely filled with insulation, the excess material is removed leaving the top of the wall flush.
"It takes from two to two-and-a-half hours for a crew to do one home", said Endres. He added that each crew ususally works on four typical size (2,000 sq. ft.) homes per day.
Superlite is not alone in marketing the Integra system. As a member of the Oldcastle Architectural Products Group, whose network of plants stretch across the US, the company's system is also available through its sister firms. One of them, Amcor in Salt Lake City, has been marketing the system for the past year with good results.
Freyermuth expects the Integra Wall System to enjoy even wider appeal now that it has received code approval for loadbearing construction from the International Council of Building Officials (ICBO). "We've already completed over a dozen commercial buildings, some as large as 100,000 square feet," he said.
"The beauty of the Integra Wall System," Freyermuth said, "is that it incorporates many of the benefits found in other types of construction. And it does so with just one product at a very economical cost."
August, 1994 Concrete Product