Birdcage Leak

Client Internal
[2010] Create animated diagram to illustrate progress of water leaking through Concrete Masonry Unit (CMU) wall during a wind driven rain storm.The main stairwell of this building is nicknamed “The Birdcage” because the street facing facade is comprised of a mesh covered open steel structure. This design creates a light filled, airy space, but also gets rather wet during wind-driven rain storms. One exceptionally heavy storm in 2008 caused leaks in some odd places. This investigation focuses on how water is getting through the CMU walls, and will be a useful resource in planning future corrective action.
The slides below give a clue to what is happening.

  • 3d model of lobby stair next to a section of the building affected by leaks.
  • Diagram showing how water can soak a CMU wall in a covered space.
  • Cutaway diagram of interior wall, showing path of water into office.
  • Water leaks from underneath interior wall and pools in a low spot on the concrete floor.
  • Exterior of CMU wall that separates stairwell from office spaces.

Or have a look at the full-size animation for the complete picture.