MCIU (Metal Cladding Investigative Unit) – Forensics Related to Metal Siding

February 1, 2019

Forensics related to metal wall installations is used to explain what determines visual acceptance.

Panel Fabrication Tolerance

  • Length
  • Squareness
    • Viewed from front
    • Measured across sheet
    • View from panel side
    • Measured across sheet

Panel Installation Tolerance

  • Panels to be installed:
    • True to line and level/plumb
    • Exposed fasteners shall be installed in a straight line
  • Field Measurements
    • Panel shall be measure with panels positioned without restraint and with enough support to prevent significant distortion or deflection
    • Substrate must be straight and true
    • Panels should be progressively installed so that overall misalignment or tolerance issues are not focused in a single panel on a wall

Panel Finish

  • Surface imperfection
    • Dents, dimples, and defects from manufacturing (coil breaks, fluting, camber)
  • Paint finish and color tolerances and performance values

Panel Deflection

  • Can be caused by environmental factors (wind)
    • Sub-structure tolerances and movement
  • Allowable deflection by code L/60
    • (IBC Table 1604.3)

Panel Face Distortion – Perceived Oil Canning

  • Can be caused by all previous identified factors
  • Percieved oil canning is not considered a cause for rejection (see MCA document)
  • Effects of thermal movement
    • Clips, slotted holes, panel breaks
  • Types of material (steel, aluminum, natural metals
    • All have differrent expantion and contraction values
      • Steel 1/16″ in 10′-0″/100° of temperature change
      • Aluminum 1/8″ in 10′-0″/100° of temperature change