Identify type, approximate thickness

  • Roof sheathing is typically either plywood or oriented strand board (OSB)
  • 3/8-inch plywood was acceptable in the past some jurisdictions. It's presence as roof sheathing may not be desirable, but its presence alone is typically not a defective condition. Check with your local building department before calling it a defect.

Discolored sheathing;

  1. Leakage:
    1. Bad penetration flashing;
    2. Damaged/failed roof-covering materials
    3. Ice dams
  2. Condensation (look for moisture source);
    1. Room exhaust fans (bathroom, laundry)
    2. Separated combustion exhaust vents
    3. Inadequate attic ventilation
  3. Decayed, damaged or otherwise deteriorated

H-Clips are NOT REQUIRED. They are an architect's or engineer's call. Their purpose is to support the sheathing at midspan of rafter bays. No expansion gap exists at the point of clip contact.

RADIANT BARRIER SHEATHING (Potential fire danger)


Radiant barrier sheathing consists of panels that have had thin foil bonded to the underside. A study by a forensic engineering firm, McDowell-Owens, suggests that this sheathing increases the potential for fire due to:

  1. Heat created at joints if the foil should become energized.
  2. Increased chance of lightning strikes.
  • Whether to include this information in a report is a decision that must be made by individual inspectors.
  • Radiant barrier sheathing will not void the warranty of most shingles.
  • Read the report here: