National Home Inspector Exam (NHIE) · Home Inspection (All Domains)
National Home Inspector Exam (NHIE): Roof Systems Concepts
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Overview
This chapter is about the roof covering, the flashing that seals its edges and openings, and the gutters that carry water away. The inspector's job is to describe the covering, look for wear and damage, and point out places where water is likely to get in.
Asphalt shingles are the most common covering. As they age they lose their granules, curl or cup at the edges, crack, and blister. Under common model codes they are typically not used on slopes below 2 in 12, and slopes from 2 in 12 up to 4 in 12 need extra underlayment. Missing or lifted shingles after wind should always be noted.
Most leaks start at flashing, not in the middle of the roof. Look closely where the roof meets a wall, at chimneys, in valleys, and around vent pipes. Gutters should be clean and sloped to downspouts, and downspouts should drop water well away from the foundation.
Key concepts
Shingle wear signs
Common signs of aging asphalt shingles are granule loss, curling or cupping edges, cracks, and blisters. Granules piled in gutters or at downspout outlets are a clue that the surface is wearing away.
Memory tipBare dark spots and curled tabs mean the roof is near the end of its life.
Minimum slope for shingles
Under common model codes, asphalt shingles are typically installed only on slopes of 2 in 12 or more. Between 2 in 12 and 4 in 12, a double layer of underlayment is required.
Memory tipBelow 2 in 12, shingles are the wrong material for the job.
Source: International Residential Code (ICC) · as of 2021
Step flashing
Small L-shaped metal pieces woven in with each course of shingles where a sloped roof meets a sidewall. Each piece laps over the one below, and the wall covering laps over the flashing.
Memory tipOne piece per shingle course. Shingle makers call for step flashing, so a single long strip is worth noting.
Chimney flashing and cricket
A chimney needs base flashing plus counterflashing set into the masonry. Under common model codes, a cricket (small peaked diverter) is typically required on the uphill side when the chimney is wider than 30 inches.
Memory tipWide chimney, uphill side: look for the cricket.
Source: International Residential Code (ICC) · as of 2021
Drip edge
Metal edging at the eaves and rakes that lets water drip clear of the fascia. Under common model codes it is typically required for asphalt shingle roofs.
Memory tipLook along the roof edge for a metal lip under the first course.
Source: International Residential Code (ICC) · as of 2021
Gutters and downspouts
Gutters collect roof water and should slope toward downspouts. Downspouts should discharge onto splash blocks or extensions that carry water away from the foundation.
Memory tipA downspout dumping at the wall undoes good grading.
Often tested
- Leaks most often start at flashing: walls, chimneys, valleys, and pipe boots.
- Note the roof covering type and any areas you could not see or walk.
- Exposed nail heads and lifted tabs invite water and wind damage.
- Granules in the gutters point to worn shingles.
3 sample questions
Verified practice questions from this unit.
Question 1. On an asphalt shingle roof, heavy loss of granules usually means what?
- ① The shingles are wearing out and losing protection from the sun
- ② The roof was installed very recently
- ③ The attic is too cold
- ④ The flashing was installed too tightly
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Answer: ① The shingles are wearing out and losing protection from the sun
Key point: Heavy granule loss = aging shingles
The granules on asphalt shingles protect the asphalt from the sun's UV rays. As a roof ages, granules wash off and collect in gutters and at downspouts. Bare or smooth patches mean the shingles are wearing out and may need replacing soon.
Wrong choices
- The roof was installed very recently: A new roof may shed a few loose granules, but heavy loss means wear.
- The attic is too cold: Attic temperature does not knock granules off shingles.
- The flashing was installed too tightly: Flashing has nothing to do with granule loss.
Question 2. What type of flashing is typically used where a sloped shingle roof meets a sidewall?
- ① Drip edge
- ② Ridge cap
- ③ Gutter apron
- ④ Step flashing
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Answer: ④ Step flashing
Key point: Roof-to-sidewall joints use step flashing
Where a sloped roof runs up against a wall, short L-shaped pieces of metal are woven in with each course of shingles. This is step flashing. The siding or counterflashing laps over it. Missing or poorly installed step flashing is a common source of leaks.
Wrong choices
- Drip edge: Drip edge goes along the eaves and rakes, not along a sidewall.
- Ridge cap: Ridge cap shingles cover the peak of the roof.
- Gutter apron: A gutter apron directs water into the gutter at the eave.
Question 3. Under typical standards of practice, if walking on a roof is unsafe, the inspector may:
- ① Inspect it from the ground, a ladder at the edge, or another safe method and report how it was inspected
- ② Walk the roof anyway, because walking is always required
- ③ Skip the roof and leave it out of the report
- ④ Remove shingles to look at the roof deck
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Answer: ① Inspect it from the ground, a ladder at the edge, or another safe method and report how it was inspected
Key point: Unsafe roof: inspect another way and state the method
Standards of practice let inspectors decide not to walk a roof that is steep, wet, fragile, or otherwise unsafe. The roof can be viewed from the ground (often with binoculars), from a ladder, or by other safe means. The report should state how the roof was inspected and any limits.
Wrong choices
- Walk the roof anyway, because walking is always required: Standards do not require unsafe actions.
- Skip the roof and leave it out of the report: The report should say how the roof was inspected or why it was not.
- Remove shingles to look at the roof deck: Inspections are non-invasive; removing shingles is not required.