DECK FAILURE BLAMED ON BAD GIRDER
Laminated veneer lumber is stiff and strong, but it’s not approved for outdoor uses — or in fact, for any service in a moist environment. Last week brought a sad reminder of the reason for this prohibition: An outdoor deck supported by an LVL carrying beam collapsed in service, injuring 14 people. “Ottawa County Sheriff Steve Kempker said about 25 people were on the back deck when it gave way in the middle and collapsed,” Fox 17 News reported (see: “14 people injured when deck collapses in Ottawa County”). The injured people were attending a public event at Weaver House, a renovated building belonging to the local parks department and commonly used for large gatherings.
Followup reports pointed the finger at the LVL girder. “GMB Architecture and Engineering inspected the deck and determined that the laminated veneer lumber used in the structural beams ‘was the wrong material to use in the outdoor environment of the deck.'” reported the Grand Haven Tribune (see: “Officials: Wrong materials used in deck construction,” by Becky Vargo). “That is because the laminate product is not suitable for the absorption of chemicals used in the pressure treatment process, which would make the wood appropriate for outdoor use.”
Inspection finds deck that collapsed in Ottawa County was built with unsuitable wood. https://t.co/Ri513TZhmj
— WOOD TV8 (@WOODTV) June 28, 2017
“The architect noted that the design called for twin, laminated beams, 1¾ inches wide by 11¼ inches deep, attached to one another and for the beam to serve as the interior spine of the deck,” the Tribune reported. “The investigation revealed that the interior of the laminated beams at the point of break had significant rotting, whereas the non-laminated lumber, which absorbed the pressure treating chemicals, was not rotted and remained structurally sound.”
Weyerhaeuser, one supplier of LVL beams, makes clear on a company website that use of LVL is restricted to dry, protected situations, writing, “Microllam® LVL should only be used in dry (interior use) applications and should not be pressure treated. LVL is not suitable for the pressure treatment process due to material density and glue lines. Also some wood species used in Microllam® LVL production may not be appropriate to absorb the chemicals used in treatment” (see: “Can Microllam® LVL Be Pressure Treated?”). But if you want an engineered beam for an outdoor application, another Weyerhaueser material, Parallam Plus PSL parallel-strand lumber, is well suited: the material is “treated to the core, eliminating field treatment when cut or drilled,” Weyerhaeuser says (see: “PARALLAM® PLUS PSL”).
Architect, builder, and JLC author Andrew DiGiammo described his experience with treated Parallam in a Coastal Contractor feature article in 2005 (see: “Case Study:Ten Years After”): “This house was one of the first buildings in which I used treated engineered wood. The entire house is built on a framework of preservative-treated Parallam girders, supported by concrete piers resting on isolated pad footings. Posts for the second- and third-story decks are also treated Parallam (continuous 6x6s that run the full height). After more than 10 years in the weather, all the Parallam timbers are in prime condition — they look as good as new.”
ANCIENT ROME’S CONCRETE SEA WALLS: HOW DID THEY WORK?
University of Utah scientists have solved a mystery from ancient Rome: How did builders 2,000 and more years ago manage to build concrete structures that could endure centuries of exposure to seawater, when modern concrete would be damaged or destroyed in that environment? The university’s website announced, “University of Utah geologist Marie Jackson studies the minerals and microscale structures of Roman concrete as she would a volcanic rock. She and her colleagues have found that seawater filtering through the concrete leads to the growth of interlocking minerals that lend the concrete added cohesion.” (See: “How Seawater Strengthens Ancient Roman Concrete,” by Paul Gabrielsen). Jackson and her colleagues have published their scholarly report in the journal American Mineralogist (see: “Phillipsite and Al-tobermorite mineral cements produced through low-temperature water-rock reactions in Roman marine concrete,” by Marie D. Jackson, Sean R. Mulcahy, Heng Chen, Yao Li, Qinfei Li, Piergiulio Cappelletti, and Hans-Rudolf Wenk).
Though immersed in seawater, Roman concrete still stands more than 2,000 years later. Our researchers know why.https://t.co/4L06RDOMvw pic.twitter.com/BjYU8aoH21
— University of Utah (@UUtah) July 5, 2017
The BBC covered the story here (see: “Scientists explain ancient Rome’s long-lasting concrete,” by Matt McGrath). The Washington Post also had a report (see: “Ancient Romans made world’s ‘most durable’ concrete. We might use it to stop rising seas,” by Ben Guarino).
FIRE DESTROYS MIXED-USE PROJECT
Yet another catastrophic fire in a large wood-framed mixed-use project under construction — this time, in Oakland, California. “The fast-moving fire ripped through the seven-story building in the area of Valdez and 23rd streets and seared neighboring structures, Acting Fire Chief Darin White with the Oakland Fire Department told reporters,” reported the Los Angeles Times (see: “Massive fire rips through 7-story building under construction in Oakland,” by Veronica Rocha). “The four-alarm blaze, which started about 4:30 a.m., sent a tower of flames and smoke into the sky that could be seen for miles, according to local news reports.”
In fact, the fire’s heat was detected from space, according to the National Weather Service. ABC7News had a report (see: “Oakland fire hot enough to be detected from space”). “The 4-alarm fire was detected on the GOES16 satellite and had an estimated temperature of roughly 900 kelvins, which translates to roughly 1,160.33 degrees Fahrenheit,” the station reported.
The project, branded “Alta Waverly,” was a typical example of an increasingly common building type. The developer’s website says, “Located in Oakland’s Broadway Valdez Specific Plan area, the 6-story structure includes 5 levels of wood framing over a concrete podium and one level of underground parking. 31,500 SF of retail space is located on the ground floor.” Building codes allow this type of construction only with extensive fire-safety provisions, including fire separation assemblies between units, ample provision for egress, and heat-activated fire sprinklers. During construction, however, none of these systems are complete or operational, and buildings are vulnerable to destruction even very late in the construction process. In recent years, numerous high-profile projects have been destroyed by fires after framing was complete, but before fire safety measures were deployed.
Some of those fires were accidental, but others were of suspicious origin — for example, a 2014 fire in downtown Los Angeles that was deliberately set (see: “Arsonist Sentenced to Prison for One of LA’s Largest Structure Fires,” by City News Service and Jonathan Lloyd). More recently, “The blaze at the Alta Waverly mixed-use building at 23rd and Valdez streets happened less than two months after an arson fire destroyed a similar development of apartments and retail space just across the Oakland border in Emeryville for the second time in a year,” the San Francisco Chronicle reported (see: “Federal investigators join search for cause in massive Oakland fire,” by Sarah Ravani, Kimberly Veklerov, Hamed Aleaziz and Steve Rubenstein). “Oakland Mayor Libby Schaaf said the city would reach out to developers to make sure they have surveillance cameras and security guards keeping watch over their construction sites,” the Chronicle reported. “She also advised the public to be vigilant and immediately report suspicious activity around such building projects.”
Meanwhile, residents of neighboring structures are out of their homes, the Chronicle reported (see: “Hundreds remain displaced by Oakland blaze,” by Hamed Aleaziz). “Residents like Hernan Carrillo, a 50-year-old AT&T technician who lives in an apartment building next door to the charred construction site on Waverly Street with his wife and young son, are staying with friends as work at the fire site continue,” the paper reported. “Carrillo was able to return to his apartment for a few minutes Friday night to gather belongings and assess the damage. ‘The roof has a bunch of holes, there’s water damage in the bedrooms — our bed is ruined and carpets and furniture are damaged,’ he said.”
HURRICANE SEASON: INTENSITY GUESSES RATCHET UP
Researchers who try to forecast the upcoming hurricane season have nudged their guesstimates up a notch or two. Insurance industry research group Tropical Storm Risk (TSR) issued a forecast update on July 4 (see: “July Forecast Update for Atlantic Hurricane Activity in 2017”). TSR’s revision was based on predictions for trade winds and sea surface temperatures: “Weaker than normal trade wind speed favours increased vorticity and reduced vertical wind shear where Atlantic hurricanes form. Warmer than normal waters provide more heat and moisture to aid hurricane formation and intensification,” the report explained.
Colorado State University’s Tropical Meteorology Project also issued an updated forecast (see: “Forecast of Atlantic Seasonal Hurricane Activity and Landfall Strike Probability for 2017”). “The odds of a significant El Niño in 2017 have continued to diminish, and most of the tropical and subtropical Atlantic remains anomalously warm,” the researchers noted. “With the increase in our forecast, the probability for major hurricanes making landfall along the United States coastline and in the Caribbean has increased as well.”
Long-range weather forecasting is unreliable and extremely imprecise, as the researchers admit: “It should be stressed that sizeable uncertainties in these predictors and in the resultant hurricane forecast still remain,” TSR noted. But as the Colorado State team pointed out, keeping an eye on the sky is a wise practice for coastal dwellers: “As is the case with all hurricane seasons, coastal residents are reminded that it only takes one hurricane making landfall to make it an active season for them. They should prepare the same for every season, regardless of how much activity is predicted.”
STATE BY STATE
North Carolina: The flying-saucer-shaped “UFO House” in the Outer Banks town of Frisco may amuse sightseers, but it’s not cool with the local zoning authorities, reports the Charlotte Observer (see: “Outer Banks vs. outer space — must a UFO house meet NC’s earthly building codes?” by Mark Price). The owner wants to operate the structure as a tourist trap, but zoning officials say that like Area 51, the non-flying saucer has to be kept locked up for reasons of safety. See also: “Outer Banks Futuro House,” on Atlas Obscura.
Pennsyvania: In an embarrassment to the local homebuilders’ association, a remodeling contractor used his good reputation and status in the group to establish credibility, then ripped off dozens of customers by taking their money and failing to perform the work, reports Pittburgh’s Action News 4 (see: “Top contractor admits stealing thousands from customers,” by Paul Van Osdof. “We keep trying to figure out what was the motive, where was the money going. Was it gambling? Was it drugs? What was it? And none of those things seem to be in play here,” said District Attorney Patrick Dougherty.
South Carolina: A Bluffton home builder and his employees have stepped up to help a local tradesman with the costs of his child’s medical condition, reports Bluffton Today (see: “Lowcountry homebuilder helps family with medical expenses”). “Coastal Signature Homes employees wanted to lend a hand when they learned Luis Calderon, an employee of Stromer Plumbing, was facing such a challenge [a child born with spina bifida],” the paper reported “Luis always shows up, does his work with a smile on his face, helps us find solutions and is a positive force on our job sites,” the home builder’s Leah England said.
