Roof

General

  • A valid permit and plans must be on-site R106.3.1
  • Spark arrestor: installed on the chimney with re-roof R1003.9.2
  • Occupancy R or U: class-A fire rating
  • Structural sheathing with strength axis (long direction of the panel unless otherwise marked) of sheathing perpendicular to rafters
  • Roof Sheathing: ≥ 3/8” OSB, 8d at 6”/6” TABLE 602.3.1
    Or 16 ga staples by 1 3/4″ at 3″/6″ TABLE 602.3.2
  • Flashing: installed in a manner that prevents moisture from entering the wall and roof through joints in copings, through moisture-permeable materials at intersections with parapet walls, and other penetrations through the roof plane. ≥ 26ga galvi if metal R903.2 & R903.2.1

Re-Roof (overlay) R908

  • 2 inspections min – Pre-roof and final
  • All previous layers of roofing shall be removed where any of the following conditions occur:
    • Existing roof structure or roofing is water soaked or deteriorated so as not to be a sufficient base for additional roofing
    • Where existing roof covering is wood shake, slate, clay cement, asbestos, or tile
    • Where the existing roof has ≥ 2  applications of any type of roofing
  • Verify missing, rusted, or damaged flashing and counter flashing, vent, caps, and metal edging are installed or replaced with new materials

Composition CRC R905.2

  • Slopes ≥ 2:12
  • 1 overlay allowed with solid sheathing 
  • Slopes 2:12 – 4:12 as above except 2 layers of 15 lb underlayment required and shingles self-sealing
  • Exposed edges of sheathing covered with L-metal or equivalent

Wood Shake CRC R905.7

4:12. Solid sheathing

Tile CRC R905.3

  • Slope 2.5:12 to 4:12 with dbl 30 lb felt, ≥ 4:12 with 30 lb felt) Solid sheathing 
  • Re-roofs to be lightweight tile unless the supporting structure is approved for heavyweight tile
  • If heavyweight tile (≥ 9 psf), see table R905.3.7 CBC 1507.3.7

Modified Bitumen R905.11

Single Ply Sprayed Foam Roofings CRC R905.14

Liquid Applied Coatings CRC R905.15

Min slope 1/4” per ft – See MI

Mineral Surface Roll Roofing CRC R905.5

Slope 1:12 – solid sheathing

Metal Roof CRC R905.10

Slope 3:12 or >. See MI.  Solid sheathing

Venting CRC R806

Per shingle manufacturer. The current code applies to the replacement of roof framing

1/150 area of the attic or 1/300 with 40%-50% vents within 3’ of the ridge

UNDERLAYMENT CRC R905.1.1

ASTM D226, ASTM D4869, ASTM D6857, ASTM D1970