Bracing for the storm: Tips on how to build against Mother Nature’s fury

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By Oliver Witte

Floods, ice, snow, sleet, downpours, wind, hurricanes, tornadoes, hail, mudslides, stifling heat, bitter cold … Arrrgh!

Builders have a fighting chance to defeat all but the worst storms if they pay attention to recent research in building techniques and materials. Rural builders who can address the weather-related concerns of owners clearly will have a competitive advantage over less informed competitors.

A great deal of money is at stake in the outcome of the fight against storm damage. State Farm Insurance reports that it pays out $3 billion a year for damage from just wind and hail – its two most common causes of home-related claims. An interactive map shows State Farm’s claims experience by state.

State Farm’s advice to builders is to follow the building codes. True, they are minimums, but they have been refined and localized over the years to the point that they provide a reasonably reliable survival guide for storms rated 3 or less – the most common varieties.

But rural builders frequently are called upon to work in areas not subject to a building code. Some unsuspecting owners might apply pressure to cut corners and gamble that the next big storm will strike somewhere else. Paul Boor, vice president of Lester Building Systems in Lester Prairie, Minn., sees this situation as an opportunity to educate the customer.

“We need to get better at risk assessment,” Boor said. Freak weather is possible anywhere in the United States, and the possibility can be calculated. The insurance companies understand this, he said, and should offer discounts that cover the cost of building to code, even where compliance is not required.

State Farm supports Boor’s argument, describing possible insurance savings as “huge” for complying with its standards.

Boor confesses that he has pressed the issue of risk assessment only recently as he has seen unexpected events cause preventable building failures.

Boor said insurance companies often content themselves with one question: “Will it comply with ASCE 7-05?” They are referring to a standard published by the American Society of Civil Engineers, which Boor called the bible of structural loads. Boor said he uses it for buildings outside jurisdictions covered by codes.

Numerous industry groups have begun to sponsor research to set standards for weather-related construction. One of the most active has been APA – The Engineered Wood Association, formerly American Plywood Association. Its website (www.apawood.org) is worth a visit. It is a common myth, APA says, that all tornadoes are so strong that structural failure is inevitable – no matter how well a building is constructed. APA research debunks that myth.

Look especially for these four APA publications:

• Building for High Wind Resistance in Light-Frame Wood Construction

• Introduction to Lateral Design

• Design for Combined Shear and Uplift From Wind. It was updated last year.

• Building for High Wind Resistance.

They are packed with tips aimed at reducing costs and improving performance. For example, Design for Combined Shear explains how additional wind uplift resistance can be achieved by providing additional nails to the shear nailing at the top and bottom of the structural panel, thus eliminating the need for most uplift straps.

Some of the most interesting research is being done on site by volunteers for the Roofing Industry Committee on Weather Issues. RICOWI is an association of associations interested in improving construction techniques and materials. Its research generally validates the effectiveness of building codes. Buildings that adhere to the code published for their area generally suffer minimal damage from most storms.

Both APA and RICOWI emphasize the importance of fasteners – correctly chosen and correctly applied. Consultant Ricardo Alverez, a member of the faculty at Florida Atlantic University, says his research has shown that ring shank roofing nails increase the performance of roofs by 100 percent at no significant increase in the cost of construction. Common nails are more likely to pull out, warned Tom Koch of Maze Nails.

In regions with moderate snow loads, Rusty Guinn, a project manager for Dynamic Fastener, recommends ColorGard S-5, an eight-foot aluminum bar that clamps to the standing seam of a metal roof and prevents snow from sliding off and damaging gutters, downspouts and vehicles and injuring people.

Avalanching isn’t necessarily a failure of the building, but products such as Snobar can retain the snow so it doesn’t land on the wrong places at the wrong time. Pricing averages from $8 to $10 per linear foot, according to Jason Nagaki, vice president of Snobar.

Some solutions to extreme weather events involve a twist on a conventional solution, such as a safe room below ground for shelter from tornadoes. The traditional safe room consists of a concrete bunker that looks like a miniature basement. It protects anyone who can reach it in time, although it is less than satisfactory. Getting to it might involve going outdoors in the rain and wind. The stairs typically were too steep and who knows what might be found at the bottom – especially if it had not been inspected and cleaned recently.

Nevertheless, Morton Buildings report an increase in owner requests for safe rooms and even full basements. Installing them is easy; anyone who can make a concrete septic tank can build one, said Dennis Jahnssen, a sales consultant for Morton in Marion, Ill.

Safe Shed after tornado

The staff of a local commercial business took shelter in this 8 x 10 foot Safe Sheds shelter as a line of tornadoes blew through the Tuscaloosa, Ala., area in 2011. Every building on the property sustained heavy damage, as did many homes and businesses nearby, yet the staff stayed safely protected.

But Morton discovered a better solution: prefabricated concrete safe rooms by Safe Sheds in Salem, Ill. They are intended to be installed above ground. Morton likes to build around them, using the space as an extra closet, a gunsafe or toolshed. Each unit is monolithic concrete, built to federal standards, without joints or seams. Even the roof is integral to the structure. The roof and sidewalls are formed with one continuous pour, leaving a decorative, two-inch lip that looks like it projects from a conventional roof. A steel access door with a reinforced latch completes the structure.

Safe Sheds makes two sizes: 8×10 and 6×6 feet. They can be used in combination for commercial buildings that must provide shelter for more than a family. Base prices start at $3,220 plus delivery.

Andersen Windows diagram

This diagram shows the difference between regular insulated glass and impact resistant insulated glass.

Windows and doors are critical components of a storm-resistant structure. If they fail, the building is left exposed to the wind and rain, ruining the contents. Andersen Corp. offers a package of components called Coastal Storm Watch that works with its regular products. The key components are impact resistant glass and stronger hardware to hold the glass in place. The laminated glass will break but it won’t shatter.

Doors, as well as walls, must be able to withstand the blows from a fierce storm, plus the door must remain operable. Engineer Jerry Hatch said he likes the roll-up doors from DBCI. Its hurricane doors work like a shutter and can be lowered before the storm hits, making it a popular choice for self-storage buildings. Bray Allen, director of research for DBCI, advises designing doors as integral parts of the wall. The difference in survivability, he said, is the wind lock – a hook that holds the door in place against the storm.

Allen praised the research being done by the Door and Access Systems Manufacturers Association.

Plyco Corp. has a formidable reputation in doors for post-frame buildings, but it has broadened its product line to include windows, fasteners and ventilation – all of which it has come to regard as components of a unified building system. It also has expanded its line to include high-performance products that meet the specifications of modern codes and standards.

“There is a need for stronger, higher-quality products,” said Fred Mancusi, Plyco’s national sales manager. They are especially valuable for alert post-frame builders as they expand their marketing efforts beyond agricultural buildings. Mancusi cited the post-frame market initiative, sponsored by the National Frame Building Association.

MFM Peel & Seal

By aggressively adhering directly to the roof deck and adjoining paraet wall, MFM Peel & Seal prevents moisture damage in the harshest environments.

No component of a weather-safe building is more important than the roof. Pictures of storm damage often show the structure in place but the roof blown off and the contents of the building drenched from the rain and wind. David Delcoma, marketing manager for MFM Building Products, stressed the importance of a water-tight underlayment. MFM produces a family of self-adhering underlayments that are applied directly to the roof deck and create a waterproof seal. The rubberized asphalt adhesive bonds to the substrate and self-seals around nails and other roofing fasteners. In effect, the underlayments provide backup protection in case of leaks in the primary system (shakes, shingles, metal, tiles).

Windbar panels

Marc Boulay, a consulting engineer, tells the story of United Parcel Service, which got tired of frequent high winds blowing the roofs off its south Florida sorting facilities. Boulay solved the problem by augmenting the standing seam metal roof with Windbar, which prevents negative wind pressure from lifting the metal roof panels. Stainless steel clamps avoid penetrating the roof. Windbar increases the strength of the roof so it can withstand greater uplift pressure. It has a stopper midway between the standing seam that prevents the roof panel from lifting up. Clamps hold the Windbar assembly in place. Six years and some hurricanes later, the roofs are still in place.

Morton’s Jahnssen said he was not surprised that State Farm Insurance would have so many claims from hail damage. Sometimes, he said, the hailstones do more than just dent the roof, creating cosmetic problems. Large hailstones can cause cracks through which leaks develop.

DECRA addressed the hail problem by engineering its stone-coated steel roof to earn a Class 4 hail rating – the highest hail rating given by Underwriters Laboratories, DECRA said. DECRA’s warranty covers hail penetration, regardless of the size of hailstones, and wind up to 120 mph.

Metro Roof Products

Metro Roof Products is part of a project in Des Moines that measures energy savings, but when fire broke out, other benefits to the roof system were realized.

The goal of weather integrity coincided with the goal of energy efficiency in an unusual retrofit of Sun Prairie apartments in Des Moines, Iowa. The roof, by Metro Roof Products, Oceanside, Calif., provides an air gap. Because the project was completed in 2010 with the help of $250,000 in federal financial stimulus funds, the terms of the grant required a demonstration that the improvements would, in fact, save energy. Continuous measurements taken at several points in the project show a savings of 25 percent to 30 percent in air-conditioning, which was expected. What was not expected was an additional savings of 29 percent on insurance. Nor was the publicity generated by the experiment expected. The project owner, Keith Denner, converted one double garage space into a showroom for the energy savings ideas incorporated in the project. Local news media picked up on the story and gave the project valuable publicity.

“But wait!” as the television commercials say.” There’s more!” Shortly after the renovation was completed, fire broke out in one of the top-floor apartments. Pete Croft, vice president of Metro Roof Products, quoted the local fire chief: “If it wasn’t for this roof system, the fire would have been catastrophic.” The metal roof from Metro confined the fire to the apartment where it started.

WEATHER FACTS
This past year has presented a veritable Murderers’ Row of extreme weather events to challenge the ingenuity of rural builders to design structures that will protect their occupants’ lives and property. And if the scientists who study global warming are correct, weather events going to keep getting even more extreme.

Even fire became a weather event last summer for swaths of the country suffering drought. Forests were so dry they could be set ablaze with a lightning strike or a carelessly discarded cigarette.

The National Weather Service last year reported nearly 30,000 incidents involving just hail, wind and tornadoes. This represents a 36 percent increase from the previous year and a 30 percent increase in 2009 from the year before.

The Institute for Business and Home Safety, a research and educational organization, declared 2012 as the “Year of the Roof.” Earlier this year the institute published Disaster Safety Review, focusing on tornadoes. It is available online at ofb.ibhs.org.

Tornadoes – nature’s most violent storm – are becoming ever more of a threat. The United States currently averages 1,200 tornadoes a year – a number that the National Oceanic and Atmospheric Administration describes as a “dramatic” increase from the 1990s

The severity of tornadoes is judged on the basis of the Enhanced Fujita Scale, from EF-0 (starting at 65 mph) to EF-5 (greater than 200 mph). EF-2, for example, is defined as sustained wind between 111 and 135 miles per hour. The National Weather Service has found that 95 percent of all tornadoes are rated EF-2 or less.

Hurricanes are rated in a Saffir-Simpson scale, starting with Category 1 at 74 mph. A Category 3 hurricane, packing sustained wind of 111 to 129 mph, is said to cause “devastating” damage. Even “well-built framed homes may incur major damage or removal of roof decking and gable ends,” according to the National Weather Service. Few buildings will survive Category 5 wind of more than 157 mph, which is as high as the scale goes. Fortunately, EF-5 and Category 5 storms are rare.

 

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