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Earthquakes and Fires
Products That Can Make A Difference

More and more these days builders are searching for ways to improve the safety features in the homes they build. In the past twelve months alone mother nature has been more than generous to Californians who have experienced devastating wildfires and the Northridge earthquake, which resulted in millions of dollars in damage to homes and other property.

In the quest to improve the safety aspects of their projects in today's tightly budgeted home building industry, builders and architects are often discouraged by the perception that safer products are more costly and might be fine for a custom home, but perhaps prohibitively expensive in entry level or move-up housing. This is not always the case. In fact, builders who think along these lines are really missing the point, namely that home buyers would undoubtedly pay a little more for reassurance and peace of mind when it comes to an added measure of safety in their home.

Another terrific benefit of safety conscious home building is the improved marketability of such products over the competition. So, with safety in mind we would like to introduce you to just a few different product types that definitely fit the bill. In the next issue we will examine several other products.

Glass Blocks

One of the earliest and best known manufacturers of glass blocks is Pittsburgh Corning Corporation, a private corporation owned by PPG Industries, Inc. and Corning, Inc. The company manufactures and distributes Pittsburgh Corning Glass Block Products. The firm was established in 1937 and markets its products worldwide. Their Southern Californian distributor of Glass Block Products is Angelus Block.

Following the Northridge quake, Pittsburgh Corning's Robert M. McMarlin, Manager, Product/Systems Evaluation and Testing, commissioned an independent study by noted structural engineer Gary Hart, Ph.D. Dr. Hart surveyed numerous buildings with external and internal glass block walls, windows, partitions and freestanding design treatments. The buildings are located in Northridge, close to the epicenter of the quake, where the g-forces were the strongest, and in Santa Monica, where glass block is used extensively.

Dr. Hart reported that, without exception, glass block was able to withstand the intense ground shaking that occurred during the earthquake that registered 6.8 on the Richter Scale, the most severe earthquake with an epicenter in an urban area. In fact, he noted that the magnitude of the g-forces in the two cities was at least two times greater than the g-force used for the design of the glass block panel systems. The engineer concluded his report by noting that an architectural design using the Pittsburgh Corning Glass Block panel system provides more than aesthetic value to a structure. Compliance with recommended detailing and the UBC requirements undeniably provide a safety feature enhancement.

The following are some of glass block's other benefits: through product and pattern selection you can control light transmission; define interiors; enhance safety through design because of inherent vandalism resistance; provide a rated, fire resistive window assembly; add insulation value due to partial vacuum within each block acting like a double-pane glass window; and Pittsburgh Corning Glass Block panels require minimal maintenance.

Post-Tensioned Masonry Fence

The only one of its kind in the United States, the Proto-II Wall Post-Tensioned Masonry Fence System has won the enthusiastic support of Southern California builders and masonry contractors involved in residential projects near the epicenter of the January 17th Northridge earthquake. Projects in the Northridge, Simi Valley, Valencia, Newhall Canyon, and Saugus areas, have had first hand experience with Proto-II fencing under catastrophic conditions and are sold on this revolutionary, cost-effective, post-tensioned masonry fencing.

Tom Reed, Sales Manager of the Angelus Block Company, the Southern California distributor for Proto-II fencing reports that approximately 12,000 linear feet of this fencing was sold to builders in those areas prior to the earthquake. "Although there was major destruction in many of the areas," he said, "it looks as though less than two percent of the Proto-II fencing was damaged by the quake." Even the walls that were damaged were easily repaired. They were also less expensive to repair than conventional masonry walls because the system is designed to be ductile and not based on the rigidity of rebar and grout in conventional systems. If, for example, there is damage, the caps can be taken off in the damaged area, rod tension released, and the masonry blocks removed and cleaned. The wall can then be rebuilt quickly, reusing the original blocks with fresh mortar and the system retensioned. Because the vertical rods are flexible and can be bent at the footings, the same procedure can be used if a swimming pool or other structure is being built and there is no available access to that area. Reed also pointed out that their fencing, unlike other types of masonry walls, tends to flex instead of collapsing during an earthquake.

Residential developers and masonry contracting firms such as the Roberts Group, AMCAL Homes, S&S Development, Design Masonry and Bob Palacios Masonry that had projects in the quake area and used the Proto-II system, found that their walls were quake resistant.

Post-tensioning of masonry combined with the new Proto-II footing approach has contributed to the enormous advances in structural integrity which the entire system has been able to make over currently used methods. The overall structural integrity of this fencing system is also improved because of the effect post-tensioning has on strengthening materials. In addition, this fencing system can withstand wind velocities of more than 100 miles per hour.

Current major California distributors are the Angelus Block Company in Southern California and the Basalite Block Company in Northern California.

Steel Studs

Residential developers originally began to use steel studs in the homes they built as a result of increasing lumber prices and the availability of lumber. This scarcity has been prompted by environmental considerations over harvesting forests in the pacific northwest, the traditional source of our wood. As continuing conservation efforts place more forests off limits to cutting, and as fewer board feet of good quality lumber are taken from reforested trees, lumber prices will rise even higher. Suddenly, steel has become an acceptable solution.

Lumber comprises approximately seven percent of the price of a new home, per a recent NAHB report. Cost may well be the prime motivator for most builders to move to steel, whereas safety is becoming just as big a factor. California Building Systems is supplying the steel for a 144-home project by Russell/Packard Development in Fontana, CA. The builder, Larry Russell, explained that he made the switch to steel because the steel framing and lower labor costs were running ten percent less than wood, and because of the added measure of safety.

The studs, track and joists used for residential steel framing are lightweight and easy to unload, move and assemble. Most often, steel is precut at the factory and comes prepunched for electrical and plumbing conduits, which saves time and money on installation and labor.

Steel structure homes offer more durability than wood and are visually impossible to distinguish from timber built homes. Unlike wood, steel framing will not warp, split, crack or twist; steel does not need to be treated for termites and is vermin proof and nonflammable. Properly built homes which utilize steel framing can be engineered to receive a seismic four rating, the highest rating available for residential dwellings. The structural strength of steel is clearly superior over wood, with increased flexibility and design, greater interior spans, increasing square footage and usable living space.

Steel components are ready to install on delivery. Labor costs for building are lower and there is no waste factor. Steel is environmentally sound, saving trees and lumber mill costs with recycled steel. The overall recycling rate of steel in the U.S. is 66%, the highest rate of any material. One of the most important reasons for building with steel is when its strength is called upon to withstand the unusual dynamic forces created by catastrophic events, when its properties and advantages become self-evident. For more information on building with steel you can contact Roberto Najera at Hometech Steel in Stanton, CA or Alan McQuoid at California Building Systems in Los Angeles.

A good example of steel stud framing used specifically for added safety is the Curtiss development project. The client's home was burned down during the 1993 Laguna Beach fire storm. The new home was designed by John W. Godfrey of San Clemente, an architect for forty-four years. Mr. Godfrey specified fire and wind resistant materials into the project wherever possible, including all steel framing throughout.