Hybrid Design Rescues Roof at Virginia Hazmat Storage Building

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

Many people enjoy the splendor of the Shenandoah Valley in Virginia. The views, spectacular fall colors, activities, history, and the generally temperate climate make the region a tourist destination and a 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 a postcard-perfect setting also ensure treacherous driving conditions in any snow or ice weather, from dust to blizzards. Interstate 81, a major north-south thoroughfare, runs through the heart of the region and connects West Virginia, Maryland and Pennsylvania to the north and Southern Virginia and Tennessee to the south.

Road safety responsibility rests with the Virginia Department of Transportation. The agency was grappling with an intricate roof issue at its hazardous chemicals warehouse in Cross Junction, where salt and de-icing products are stored to keep nearby roads safe for the ride.

The building is in a rural, hilly location and salt is distributed in the structure through skylights. However, the existing hatches began to fail. Age, weather and salt corrosion made it necessary for 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 roof solution that is expected to provide decades of service. The subsequent design is efficient, cost-saving and durable and activates three of the most important criteria for VDOT’s project requirements.

Narrow project scope

The scope of the project was not wide. The priority was to replace the skylights and roof, which were 1,960 square feet. However, the hatches had to be custom built, corrosion resistant, and structurally strong enough to support the weight of the salt while it was being loaded.

“In early autumn, salt is loaded into the building through three skylights that are accessible from the upper part of the site,” said Stephanie Stein, lead architect on the project for Gauther Alvarado. “In winter, the salt stored in the three bays of the building is called up in the lower part of the site as a reaction to snow events.”

The crews installed three BILCO skylights that were lined to protect against corrosion from salt stored in the facility.

The top priority was installing skylights that could withstand the corrosive effects of salt. The architects selected three aluminum roof hatches made by BILCO. The hatches are 3 feet, 11 inches wide, and 11 feet long. They are made with stainless steel fittings of type 316L, the most corrosion-resistant type of stainless steel. The curbs were coated with an asphalt-based liquid coating to provide an additional protective layer for the concrete inside the building.

“BILCO offers roof hatches made of stainless steel. However, since this is a project that was designed and built on the basis of a state budget, we provided a more economical solution, ”Stein said.

To protect the inside of the skylight that comes in contact with the salt, a team from Rhino Linings in Winchester, Virginia installed a liner. Similar to the lining on truck loading areas, the spray-on material protects against corrosion and at the same time offers excellent resistance to abrasion, impact and chemicals.

“With this solution, we have combined the durability of the prefabricated aluminum roof hatches from BILCO with the corrosion-resistant properties of the loading area,” said Stein.

Dinks staff installed the skylights while the roof team installed EPDM on the rest of the roof. The durability of the roof hatches with the unique lining and the EPDM roofing material is intended to extend the durability of the roof up to 35 years.

Withstand salt

The team of architects also designed another unique solution to protect hatch durability.

“One of our main concerns during the design phase was the extra force that is exerted on the skylights during the salt load,” said Stein.

The time-saving design allows the driver to drain a lot of salt through structurally reinforced hatches. The roof hatches with the lining and a roof with an EPDM roof membrane are intended to extend the life of the roof to up to 35 years.

They designed a structural steel bumper to add extra support to the skylight. If the hatches are open before the building is loaded with salt, the skylight covers rest on the bumpers. “The extra force applied to the skylight covers during the salt load is then transferred directly to the steel bumpers to protect the structural integrity of the skylights,” Stein said.

The unique design of the building and the roof allows a faster and more efficient solution for the storage of the chemicals. In dangerous storage buildings with no roof access, salt must be carried by front loaders or some other type of transport. As the storage of chemicals is subject to stricter regulations, the drop-and-go solution is much cheaper for the environment. Street crews access the salt from the lower part of the building.

Worrying corrosion

The corrosive nature of salt can affect almost any building material. When Dinks Construction started the project, workers were experiencing problems with the decay of some concrete walls caused by salt corrosion. The teams tore off part of the wall and rebuilt it before putting the roof back on.

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

“The building contains chemicals against icing, de-icing and snowmelt,” said Stein. “All of these chemicals contain salt. Since this is a government project, longevity was an issue. As a result, any surface that comes in direct contact with the salt had to be resistant to corrosion in order to extend the life of the building in this extremely corrosive environment. “

Another problem was the increased weight of the roof hatch with the protective lining. BILCO provided a lifting mechanism to manipulate the roof hatch and protective panel.

Underrated project

The tiny town of Cross Junction sits on the edge of a small stretch of West Virginia. Located several miles from the freeway, the building 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 left unnoticed by visitors to the region.

However, the building plays an important role in the safety of drivers on the region’s roads. It might not be noticeable, but drivers would certainly know if snow-covered roads are untreated when trying to navigate them. “It’s one of those buildings that 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. Each project has its own different and difficult equations, but the Cross Junction project raised questions that architects rarely see.

“That was a fun project because it was very different,” said Stein. “This was our second roof and skylight system that we developed for VDOT. We had the opportunity to learn some lessons from the initial roof system replacement. We hope that we will be able to adapt this prototype of the roof system for other VDOT locations in the future as well. “

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

TEAM

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

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

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

MATERIALS

Skylights: Custom made roof hatches made of aluminum, BILCO, bilco.com

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