Washington National Cathedral


Location: Washington, DC
Age/Built: Construction began 1907
Seismic Retrofit, Services, Stabilization of Historic Structures, Testing and Analysis

Project Background:

  • The Washington National Cathedral is the sixth largest cathedral in the world and second largest in the US
  • A member of the National Register of Historic Places it was the site of funerals for Dwight Eisenhower, Ronald Reagan, and Gerald Ford
  • The cathedral is designated as the ‘National House of Prayer’ by Congress and houses the remains of historical figures such as Helen Keller and Woodrow Wilson
  • Ranked third on the List of America's Favorite Architecture by the American Institute of Architects

Challenges Presented:

  • The cathedral was badly damaged during the 2011 Virginia earthquake
  • Project designers determined a systematic reinforcement of the cathedral’s buttresses was critical. This would first require carefully dry coring into the historic limestone, a task many told the project team was impossible
  • Any potential repairs would need to be discreet and leave normal parish operations undisturbed during their execution
  • Additionally, the team needed to furnish a compatible material to bond with and mobilize anchors within the masonry substrate

Services and Solutions:

  • Masonry Solutions International began by evaluating the limestone structure and developing a custom approach that included specially calibrated diamond composite drill segments
  • Working with the project team, Masonry Solutions then determined the optimal layout for MSI’s advanced ROMEO I coring equipment, which allows for long-bore coring without the use of water
  • Several core locations required complex, precision angled drilling
  • Masonry Solutions’ drillers applied their extensive knowledge, providing dozens of lengthy, 3” diameter core holes with the utmost care for the continuing operations of this venerable institution
  • MSI and its laboratory engineers then coordinated with the cathedral’s design team to develop a custom Compatible Injected Fill (CIF) to mobilize the supplied anchors within the limestone, providing superior bond and enhanced structural performance
  • This CIF was uniquely developed using white cement to match the limestone masonry and air entraining agents to provide the masonry with a longer lasting repair
  • The National Cathedral’s appearance was maintained and no service interruptions were experienced throughout Masonry Solutions’ work
  • Thanks to the extensive (yet principally invisible) intervention, this landmark is able to continue along its historic path unimpeded