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Roofing Terminology

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The roof sheathing on your home ties together your roof trusses or rafters and provides a foundation for the underlayment and shingles that are installed over it. Problems with your roof sheathing are usually easy to spot and should be repaired as soon as possible.

Roof Sheathing and Your Roofing System

Roof sheathing is nailed to the roof rafters or trusses and the underlayment and shingles are installed on top of it. Sheathing is normally made of plywood or composite board and 1/2 inch or 5/8 inch are the most common thicknesses used.

Roof sheating is susceptible to exterior moisture penetration or interior condensation, so your sheathing should be inspected on a regular basis to catch any potential problems before they have a chance to escalate. Here are some things to keep an eye out for when inspecting your roof sheathing:

  • Interior moisture. Get in your attic to do a visual inspection of the underside of your sheathing; if you see any staining around the edges or moisture on the floor, you should call a roofing contractor.
  • Daylight. Any daylight that's visible through the underside of the sheathing is an indication of a problem that should be corrected before water intrusion occurs.
  • Exterior cosmetics. Roof trusses are normally 24 inches apart; if you can see any sagging of your roof between trusses, it's a pretty good indication that you have sheathing that's beginning to fail.

An annual inspection of your roofing system by you or a qualified roofing contractor is a good way to keep small roofing problems from becoming expensive restoration projects. If you're planning a new roof, your roofing contractor should do a thorough sheathing inspection prior to installing any new shingles.

Roofing Terms