Chapter 24 Quiz: Roofing Systems
Multiple Choice
1. The primary purpose of underlayment in a roofing assembly is to:
a) Provide additional insulation b) Serve as a backup water barrier if the finished roofing is breached c) Reduce the weight load on the roof decking d) Reflect solar radiation and reduce cooling costs
Answer: b — Underlayment is the insurance layer. It's not insulation, it doesn't bear load, and reflectivity is a property of some finished materials but not underlayment's primary function.
2. A "30-year shingle" rating is best understood as:
a) A guarantee that the shingle will last 30 years under any installation conditions b) A marketing designation based on controlled testing that may significantly overstate real-world performance c) A manufacturer warranty that covers replacement at no cost for 30 years d) An industry-standard certification that requires independent testing of each batch
Answer: b — The rated lifespan depends heavily on installation quality, attic ventilation, climate, and pitch — factors the manufacturer has no control over after sale.
3. Which of the following has the greatest effect on how long asphalt shingles actually last?
a) The brand of shingle purchased b) The color chosen c) Attic ventilation and installation quality d) Whether the old shingles were removed before installation
Answer: c — Attic ventilation and installation quality are the two factors most strongly correlated with real-world shingle lifespan in field studies.
4. Standing seam metal roofing differs from exposed fastener metal roofing primarily because:
a) Standing seam uses thicker metal b) Standing seam panels attach via concealed clips, leaving no fastener penetrations on the weather surface c) Standing seam is only available in steel, while exposed fastener comes in multiple metals d) Standing seam is only appropriate for commercial buildings
Answer: b — The concealed fastener system is the defining feature; no holes in the weather surface means no potential leak points at fasteners.
5. Before installing clay or concrete tile roofing on an existing house, the most critical professional evaluation needed is:
a) An asbestos assessment b) A structural engineer's evaluation of the roof framing's load capacity c) A thermal performance calculation d) A permit for the color change
Answer: b — Tile is dramatically heavier than asphalt. Roof framing designed for asphalt loads may not safely support tile. This is a structural safety question.
6. TPO roofing has replaced EPDM as the dominant commercial flat roofing material primarily because:
a) TPO is less expensive than EPDM in all applications b) EPDM is no longer manufactured c) TPO's light color improves reflectivity/cooling performance and its seams are heat-welded rather than taped d) TPO performs better in cold climates
Answer: c — Reflectivity and welded seams (stronger than taped EPDM seams) are the primary advantages driving TPO adoption.
7. Most roof leaks occur:
a) In the middle of large shingle fields b) At transitions: chimneys, pipe boots, valleys, skylights, and wall junctions c) At the ridge d) At gutter attachment points
Answer: b — Estimates range from 60–90% of roof leaks originating at flashing transitions rather than the field of the roof.
8. Chimney counter flashing differs from step flashing in that counter flashing:
a) Covers only the downslope face of the chimney b) Is cut into the chimney masonry and bends down over the step flashing, allowing independent movement c) Is made of lead rather than aluminum d) Is only required on chimneys wider than 24 inches
Answer: b — Counter flashing is embedded in the masonry reglet and creates the two-piece system that allows thermal and settlement movement between roof and chimney.
9. When should you NOT attempt to walk on your own roof for inspection?
a) Only when it is actively raining b) Only during winter c) Whenever the roof is wet, has a pitch above 6:12, you're alone, it's tile, or you're not comfortable at height d) Only on roofs that are over 15 years old
Answer: c — All of the conditions in option c are legitimate individual reasons not to walk a roof. Wet alone is disqualifying.
10. The "water control sequence" principle means:
a) Water should be collected in a tank before being discharged b) Roofing and cladding layers must be lapped with upper courses over lower ones so water runs over seams rather than into them c) Water must be heated before it can damage wood framing d) Drainage must always flow to the right side of the house
Answer: b — The water control sequence is the shingling principle applied throughout exterior construction: every layer laps over the one below to maintain downhill water flow over seams.
Short Answer
11. Explain why a well-ventilated attic extends asphalt shingle life. What specifically does inadequate ventilation do to shingles?
A well-ventilated attic maintains temperatures closer to outdoor air temperature by flushing hot air through continuous soffit-to-ridge airflow. Without adequate ventilation, attic temperatures can reach 150–160°F in summer. This heat acts on the underside of the roof decking and, through it, on the asphalt shingles above. The heat accelerates the oxidation of the asphalt binder, causing it to become brittle, lose flexibility, and shed granules more rapidly. The same thermal stress causes the shingle to expand and contract more dramatically with daily temperature cycles, working loose the granule mineral coating. Shingles on a poorly ventilated roof may achieve only half the lifespan of the same shingles on a well-ventilated roof in the same climate.
12. Your neighbor tells you they need a new roof and the contractor said they should "just put the new shingles right over the old ones to save money." What are the key concerns with this approach?
Several concerns: First, building code limits the number of shingle layers (typically two maximum) because of weight loading on the roof framing. Second, new shingles installed over old ones conform to the waviness and irregularities of the old layer rather than lying flat — this affects appearance and can affect drainage. Third, installing over old shingles means the decking underneath is never inspected; damaged or soft decking that would be visible and repairable during a full tear-off remains hidden and can worsen. Fourth, most shingle manufacturers void their warranty if the product is installed over existing shingles. The labor savings on a "re-roof over" versus a tear-off is real, but it comes with meaningful trade-offs.
13. List three specific flashing locations on a typical house and describe the failure mode that is most common at each location.
Any three of: - Pipe boots: Neoprene rubber boots crack and split from UV exposure after 10–15 years, allowing water to run down the pipe into the ceiling below. - Chimney step flashing: Step flashing installed as a single piece rather than individual courses, or improperly lapped, allows water to work its way horizontally behind the flashing during wind-driven rain. - Chimney counter flashing: Sealant-only installation without metal cut into a masonry reglet; the sealant cracks and separates within a few years, leaving a gap between the masonry and step flashing. - Valleys: Woven valleys on low-slope roofs trap water at the multiple shingle layers; closed-cut valleys sealed with roofing cement fail when the cement dries and cracks. - Skylight corners: The geometric complexity of four-corner flashing means shortcuts at corners are common; improperly sealed corners allow water infiltration that often doesn't appear until well inside the house.