Historic Roofs: The Pentagon
The U.S. Department of Defense is headquartered in the building named solely for its shape, the Pentagon. Although the name refers to the building, it now is also used to refer to the agency itself. The Pentagon is the largest office building by floor area in the world yet it is designed so that a person can walk from any one point to another in less than seven minutes. The design was made to be both functional and elaborate, with a roofing system to match.
Creating The Pentagon
The creation of the Pentagon was in response to a growing War Department after World War I and then the anticipation of being pulled into another World War. In 1941, the U.S. War Department, now known as the Department of Defense, was spread throughout several buildings. It was proposed that one building be created to house the War Department instead of more separate buildings. In July 1941 the proposal was passed and the design and building of the Pentagon began. The project was finished and dedicated in January 1943.
The original site for the new building was set to be the Arlington Farms site, which was the shape of an irregular pentagon. This land shape began the design of the building. However, President Roosevelt in the end decided to choose a different site and though the pentagon shape was no longer needed, it was retained instead of starting over with a costly redesign.
The main part of the complex is the Pentagon building, which is a 5-acre central plaza. It has five sides, five floors above ground, two floors below ground and has five-rings of corridors per floor. The total corridor length adds up to 17.5 miles, with 6,500,000 square feet of floor space. It houses approximately 28,000 military and civilian employees and another 3,000 non-defense workers.
The Pentagon Roof
The original Pentagon roof had two different elements. The inner three rings of the 5-ring pentagon were tar-pitch built-up roof systems and the inner and outer rings along with five corridors that extend from the center to the outer ring had slate roof systems. The slate roof was nailed to a wood sheathing that covered concrete at a 23-degree slope. However, a much of this was destroyed on the fateful day of 9/11.
When Flight 77 hit the Pentagon on September 11, 2001, it dumped jet fuel on the roof that then ignited. The slate roof, which did its job protecting the building from water, actually hindered firefighters efforts. The wood sheathing below the slate had begun to burn and the slate prevented water from extinguishing the fire. It was not until the slate was broken through that the fire could be stopped. 40,000 square feet of the roof was damaged and needed to be replaced
The National Roofing Contractors Association organized the replacement of the Pentagon roof with the roofing industry contributing labor, materials and generous donations. The new roof has improved fire stops but still has the slate roof that had worked so well for many years.
Roofing systems play a big part in fire prevention. Old Pro Roofing, your local Fort Worth roofing contractor, offers a free inspection and consultation to discuss your roof system and what roof systems work best for fire prevention. Call today to schedule your free roof inspection.