Steep-slope Roof System Mockup Characteristics

Steep-slope mockups must provide characteristics similar to those typically found on most steep-slope roofs. These characteristics are essential to ensure standard testing conditions are achieved and fair performance exams are administered. All steep-slope mockup designs should include the following characteristics:

  1. Deck material must be one of the following:
    • A minimum of four-ply, nominal thickness of 1/2 -inch-thick (actual thickness of 15/32-inch thick) plywood installed over supports spaced no more than 16 inches on-center
    • A minimum four-ply, nominal thickness of 5/8 -inch-thick (actual thickness of 19/32-inch-thick) plywood installed over supports spaced no more than 24 inches on-center
  2. A slope of no less than 4:12 and no greater than 8:12
  3. A total field area of no less than 120 square feet
  4. A minimum of 10 lineal feet of hip and ridge in any combination that must include a minimum of 4 lineal feet of hip and 4 lineal feet of ridge. The decking at the ridge must include a 1-inch opening on each side of center to accommodate the installation of continuous ridge vent materials.
  5. The mockup must remain stationary and secure always for the duration of any performance exam
  6. One rake edge
  7. One hip roof area
  8. One valley no less than 4 lineal feet in length
  9. A minimum 4-inch (nominal) fascia board on all lower drip edges
  10. Lower drip edge must be less than 36 inches above ground

NRCA also recommends a separation sheet, such as rosin building paper, be affixed on steep-slope mockup wood decks for performance assignments requiring use of self-adhering ice and water protection membrane for easier material removal after exam completion.

New mock-up pictures coming soon


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