Inspection, Defect Identification, and Repair

Why Systematic Roof Inspection Matters

A shingle roof can fail long before it leaks visibly into the building. Blistering paint, rotted decking, and mold in the attic are often the first signs an owner notices — by then, repair costs have multiplied. A trained roofer who catches defects early saves the owner money and protects the structure. Systematic inspection also protects you: working on a roof with unknown weak spots is a fall and injury hazard. Always perform a visual scan of the deck and surrounding areas before you put your full weight on any section.

Personal Protective Equipment and Fall Protection

Before stepping onto any roof, confirm your PPE is in place. At a minimum you need:

• Hard-soled, slip-resistant footwear appropriate for roofing
• Hard hat when workers or tools may be overhead or below
• Safety glasses
• Fall protection system — on residential slopes at or above 4:12, OSHA requires a personal fall arrest system (PFAS), guardrails, or a safety net whenever you are working at six feet or more above a lower level. Anchor points must be rated for the load. Inspect your harness, lanyard, and anchor before each use. Never tie off to a vent pipe, TV antenna, or any unrated anchor.

Set up a tools tether or use a tool pouch so dropped tools do not become projectiles for people below. Post a warning barrier or spotter at ground level if there is any pedestrian traffic under or near the work area.

The Systematic Inspection Protocol

A good inspection moves in a defined sequence so nothing is skipped. Use a written checklist and mark the location of every defect. One reliable sequence for asphalt shingles:

1. Ground-level overview — step back and look at the whole slope. Uneven shadow lines suggest lifted tabs or improper exposure. Cupping, curling, or missing shingles are often visible from the ground.

2. Eave-to-ridge walk — start at one rake edge and walk up-slope, examining each course. Check exposure consistency, tab alignment, and joint offsets.

3. Ridge and hip inspection — check ridge cap shingles for cracking, lifting, and sealant condition.

4. Penetration and flashing check — inspect step flashing at walls, pipe boots, skylight curbs, and valley liners for gaps, open joints, and corrosion.

5. Probe suspect areas — use a flat bar gently to lift a suspect tab; soft or spongy decking beneath indicates rot.

Record each defect with: location (course number and horizontal position from rake edge), defect type, and recommended corrective action.

Seven Common Asphalt Shingle Defects

1. Fishmouthed shingles — The lower edge of a tab curls upward, leaving an opening that admits water and wind. Caused by improper nailing (nail driven too high or too low) or by a buckle in the underlayment. Repair: remove the affected shingle, correct the underlayment or re-nail the course below, and install a replacement shingle.

2. Exposed nail heads — Nails visible above the shingle surface indicate nails driven too high or missed the nailing zone. Each exposed nail is a leak point and a wind-uplift weak spot. Repair: apply approved roofing sealant over each head, or remove and re-nail at the correct location and seal.

3. Improper exposure — Courses laid with more or less exposure than the manufacturer specifies leave either double coverage gaps or excessive UV exposure on the underlayment. Confirm with a tape measure; correct exposure for standard three-tab shingles is typically 5 inches, but always verify the product's installation instructions.

4. Mis-offset (aligned) joints — Vertical joints in adjacent courses must be offset by at least a minimum distance specified by the manufacturer (commonly several inches) so water cannot channel straight through two layers. Aligned joints create a direct path to the deck. Repair requires removing and re-laying the affected courses with correct offset.

5. Unsealed valley edge — Open-cut or woven valleys require that shingle edges be sealed to the valley flashing. A missing or cracked sealant bead allows wind-driven rain to lift the edge and enter the valley. Repair: clean the edge, apply roofing sealant, and press the tab flat.

6. Lifted tabs — A tab that has separated from the sealant strip below it is vulnerable to wind uplift and allows water infiltration. Repair: apply a dab of roofing sealant under each lifted tab and press firmly; in cold weather, warm the sealant gently per manufacturer guidance.

7. Improper or missing starter strip — Without a proper starter course at the eave, joints in the first course have no shingle layer beneath them. Evidence: look at the eave edge from below or check whether the first visible course joints have backing. Repair requires adding a starter strip or removing and re-laying the first course.

Performing an Acceptable Repair

Removing a damaged shingle without disturbing sound courses is a fundamental skill:

1. Lift the tabs of the course above the damaged shingle to expose the nails holding it.

2. Use a flat bar to back out or cut the nails. Slide the damaged shingle free.

3. Inspect the deck surface beneath; replace or repair any soft decking before proceeding.

4. Slide the replacement shingle into position, aligning it with the exposure and offset of the surrounding courses.

5. Nail in the manufacturer's specified nailing zone — typically just above the sealant strip — using the correct number of nails per shingle (commonly four nails for standard three-tab; follow product instructions).

6. Press the overlying tabs back down over the new shingle's nail heads. Apply sealant under any tab that does not lie flat on its own.

A passing repair has no exposed nail heads, all tabs lying flat, no open joints at the edges, and the re-nailed area secure against uplift.

Documentation

Your written defect log and typed inspection summary are legal-quality records. Include: inspection date, roof address or identifier, your name, weather conditions, each defect's location and type, recommended action, and photos with captions. Clear records protect both you and the property owner if questions arise later.