CLC Weatherproofing & Energy Efficiency 3 — Questions and Answers
Question 1: A homeowner reports ice dams forming every winter on a low-slope roof section. What is the most effective long-term solution?
- Install electric heat cables along the eaves
- Add attic ventilation and increase attic insulation to keep the roof deck cold (Correct answer)
- Apply a thick layer of roofing tar at the eave
- Replace shingles with metal roofing
Correct answer: Add attic ventilation and increase attic insulation to keep the roof deck cold
Ice dams form when a warm roof deck melts snow that refreezes at the cold eave; proper attic insulation and ventilation keeps the entire deck cold, preventing the cycle.
Question 2: What is the correct installation sequence for flashing at a window rough opening to ensure a weather-tight assembly?
- Sill pan first, then jamb flashing, then head flashing (Correct answer)
- Head flashing first, then jamb flashing, then sill pan
- Jamb flashing first, then sill pan, then head flashing
- Install all flashing simultaneously and seal corners with caulk
Correct answer: Sill pan first, then jamb flashing, then head flashing
Flashing is installed from the bottom up — sill pan first, then jamb, then head — so each upper layer laps over the one below and sheds water properly.
Question 3: Which metric is used to measure the overall energy efficiency of a whole building envelope per the Energy Star program?
- EER (Energy Efficiency Ratio)
- ACH50 (Air Changes per Hour at 50 Pascals)
- HERS Index (Home Energy Rating System) (Correct answer)
- COP (Coefficient of Performance)
Correct answer: HERS Index (Home Energy Rating System)
The HERS Index rates a home's overall energy efficiency; a score of 100 is code minimum and lower scores indicate a more efficient home.
Question 4: When caulking an exterior joint between dissimilar materials (wood siding and brick), which caulk type is most appropriate?
- Latex painter's caulk
- Polyurethane sealant (Correct answer)
- Silicone bathroom caulk
- Butyl rubber caulk
Correct answer: Polyurethane sealant
Polyurethane sealant adheres well to both porous and non-porous dissimilar materials and remains flexible through thermal expansion cycles.
Question 5: What is the function of a vapor retarder placed on the warm-in-winter side of a wall assembly?
- Prevent air infiltration from outdoors
- Slow moisture diffusion so warm moist air cannot reach the cold dew point zone within the wall (Correct answer)
- Improve the wall's fire resistance rating
- Provide a drainage plane for bulk water
Correct answer: Slow moisture diffusion so warm moist air cannot reach the cold dew point zone within the wall
A vapor retarder on the warm side slows water vapor migration into the wall cavity, preventing condensation at the cold sheathing.
Question 6: A lead carpenter is installing rigid foam insulation on the exterior of a wood-framed wall. What fastener detail is critical for long-term performance?
- Use standard roofing nails driven flush
- Use long screws with large-diameter washers to prevent pull-through and compress the foam firmly (Correct answer)
- Staple every 6 inches along the edges only
- Rely on construction adhesive alone without mechanical fasteners
Correct answer: Use long screws with large-diameter washers to prevent pull-through and compress the foam firmly
Rigid foam requires long screws with large washers to distribute the load and prevent the screw head from pulling through the foam over time.
Question 7: Which of the following best describes the 'stack effect' and its impact on a building's air infiltration?
- Horizontal wind pressure forcing air through wall cracks at mid-height
- Warm buoyant air rising and escaping at the top while cold air is drawn in at the bottom, driving infiltration (Correct answer)
- Mechanical exhaust fans creating negative pressure in the attic only
- Solar radiation heating the south wall and pushing air through gaps
Correct answer: Warm buoyant air rising and escaping at the top while cold air is drawn in at the bottom, driving infiltration
The stack effect occurs as warm air rises and exits through upper openings, creating negative pressure that draws cold outside air in through lower openings.
CLC Weatherproofing & Energy Efficiency 3
A homeowner reports ice dams forming every winter on a low-slope roof section.
What is the most effective long-term solution?