Hybrid Design Rescues Roof at Virginia Hazmat Storage Building

Architects from Gauther Alvarado Associates designed a unique hybrid roofing solution for hazardous chemical storage building for the Virginia Department of Transportation in Cross Junction, Virginia. Photos: Dylan Francis Photography

Many people enjoy the splendor of Virginia’s Shenandoah Valley. The vistas, spectacular autumn colors, activities, history and generally temperate climate make the region a tourist destination and wonderful place to call home.

Except when it snows. While the region only receives an average of 19 inches of snow per year — well below the national average of 28 — driving can be risky. The peaks and valleys that make the region such a pretty-as-a-postcard setting also make for treacherous driving conditions in any snow or ice weather pattern, from a dusting to a full-bore blizzard. Interstate 81, a major north-south thoroughfare, travels through the heart of the region and links to West Virginia, Maryland and Pennsylvania in the north, and southern Virginia and Tennessee in the south.

The responsibility for making the road safe for travel falls on the Virginia Department of Transportation. The agency faced a complicated roofing issue at its hazardous chemical storage building in Cross Junction, where it keeps salt and de-icing products to help keep nearby roads safe for travel.

The building sits in a rural, hilly location and salt is distributed through roof hatches in the structure. The existing hatches, however, started to fail. Age, weather and corrosion from salt required VDOT to replace the entire roof, especially the hatches.

Working with architect and project engineer Gauther Alvarado Associates, general contractor Dinks Construction and Don Largent Roofing, VDOT approved a hybrid roofing solution that is expected to provide decades of service. The eventual design is efficient, cost-saving and durable, checking off three of the most important boxes on VDOT’s project requirements.

Narrow Project Scope

The scope of the project was not wide. The priority was to replace the roof hatches and the roof, which measured 1,960 square feet. The hatches, however, needed to be custom-built, corrosion-resistant, and structurally strong enough to support the weight of the salt during loading operations.

“In the early fall, salt is loaded into the building through three roof hatches accessible from the upper part of the site,” said Stephanie Stein, lead architect on the project for Gauther Alvarado. “During the winter, the salt stored in the building’s three bays is accessed on the lower part of the site as needed, in response to snow events.”

Crews installed three roof hatches from BILCO that were equipped with a liner to protect against corrosion caused by salt that is stored in the facility.

The top priority was to install roof hatches that could withstand the corrosive effects of salt. Architects selected three aluminum roof hatches manufactured by BILCO. The hatches are 3-feet, 11-inches wide and 11 feet long. They are manufactured with Type 316L stainless steel hardware, which is the most corrosion-resistant type of stainless steel. The roof hatch curbs were coated in an asphalt-based liquid coating to provide an additional layer of protection for the concrete inside the building.

“BILCO offers stainless steel roof hatches, but since this is a project that is designed and built on a government budget, we provided a more economical solution,” Stein said.

To protect the interior of the roof hatch that comes into contact with the salt, a team from Rhino Linings in Winchester, Va. installed a liner. Similar to the lining on truck beds, the spray-on material protects against corrosion while also providing excellent abrasion, impact and chemical resistance.

“With this solution, we combined the durability associated with the BILCO pre-manufactured aluminum roof hatches with the corrosion-resistant properties of the truck bed liner,” Stein said.

Dinks’ workers installed the roof hatches while the roofing team installed EPDM on the remainder of the roof. The durability of the roof hatches with the unique liner applied and the EPDM roofing material is expected to extend the roof’s durability up to 35 years.

Standing Up to Salt

The architectural team also designed another unique solution to protect the durability of the hatches.

“One of our prime concerns during the design phase was the additional force exerted on to the roof hatches during salt loading operations,” Stein said.

The time-saving design allows drivers to drop off loads of salt through hatches that are structurally reinforced. The roof hatches with the liner and a roof with an EPDM roofing membrane is expected to extend the roof’s durability up to 35 years.

They designed a structural steel bumper to provide additional support to the roof hatch. When the hatches are open prior to loading the building with salt, the roof hatch covers rest upon the bumpers. “The additional force applied to the roof hatch covers during the salt loading is then directly transferred to the steel bumpers to protect the structural integrity of the roof hatches,” Stein said.

The unique design of the building and the roof allows for a quicker, more efficient solution for storing the chemicals. For hazardous storage buildings without roof access, salt has to be moved by front-end loaders or some other type of conveyance. With the chemical storage facing more stringent regulations, the drop-and-go solution is much more favorable for the environment. Road crews access the salt from the lower part of the building.

Worrisome Corrosion

The corrosive nature of salt can impact almost any building material. When Dinks Construction started the project, workers found issues with decay in some concrete walls caused by salt corrosion. Teams tore out a portion of the wall and rebuilt it before replacing the roof.

Road salt can also cause paint corrosion on vehicles, and can even impact brakes, electrical systems and wiring. The American Trucking Association Foundation reported a direct correlation between increased magnesium chloride use and a significant escalation in truck corrosion and electrical system damage. Some states are even decreasing the use of sodium chloride in favor of magnesium chloride with added corrosion inhibitors.

“The building holds anti-icing, de-icing and snowmelt chemicals,” Stein said. “All of these chemical agents contain salt. Since this is a government project, longevity was a concern. As a result, any surface that comes into direct contact with the salt needed to be corrosion resistant to increase the lifespan of the building in this extremely corrosive environment. “

One additional concern was the increased weight of the roof hatch with the protective liner. BILCO provided a lift mechanism to handle the roof hatch and the protective lining.

Underappreciated Project

The tiny town of Cross Junction sits on the border of a small piece of West Virginia. The building is located several miles from the interstate, and is hardly the Lincoln Memorial in terms of an architectural masterpiece. Functionality in this project was more important than visual appeal. The structure is largely unnoticed by visitors to the region.

Yet, the building plays a key part in keeping drivers safe as they travel the region’s roadways. It might not be flashy, but drivers would certainly know if snow-covered roads were untreated as they attempt to navigate them. “It’s one of those buildings you don’t pay attention to until you actually need it,” Stein said.

The design and construction required ingenuity, attention to detail and creativity in solving some unique challenges. Every project has its own distinct and difficult equations, but the Cross Junction project posed questions that architects rarely see.

“This was a fun project because it was quite different,” Stein said. “This was our second roof and roof hatch system that we designed for VDOT. We had the opportunity to incorporate a few lessons learned from the first roof system replacement. It is our hope that we will continue to adapt this roof system prototype for additional VDOT sites in the future.”

About the author: Thomas Renner writes on building, construction, engineering and other trade industry topics for publications throughout the United States.

TEAM

Architect: Gauther Alvarado Associates, Fairfax, Virginia, gaa-ae.com

General Contractor: Dinks Construction, Linville, Virginia, dinksconstruction.com

Roofing Contractor: Don Largent Roofing Inc., Harrisonburg, Virginia, donlargentroofing.com

MATERIALS

Roof Hatches: Custom-made aluminum roof hatches, BILCO, bilco.com

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