GAF Ventilation & Attic Systems 1 — Questions and Answers
Question 1: What is the minimum net free area (NFA) of ventilation required per 150 square feet of attic floor space when there is no vapor barrier?
- 1 square foot per 100 sq ft
- 1 square foot per 150 sq ft (Correct answer)
- 1 square foot per 300 sq ft
- 1 square foot per 50 sq ft
Correct answer: 1 square foot per 150 sq ft
Building codes typically require 1 square foot of NFA per 150 square feet of attic floor space when no vapor retarder is installed.
Question 2: Which type of attic ventilation system uses both soffit vents and a ridge vent to create airflow through natural convection?
- Power ventilation system
- Balanced ventilation system (Correct answer)
- Exhaust-only system
- Intake-only system
Correct answer: Balanced ventilation system
A balanced ventilation system pairs soffit (intake) vents with ridge (exhaust) vents so cool air enters low and hot air exits high via natural convection.
Question 3: GAF's Cobra® Ridge Vent products are designed primarily to function as which component of attic ventilation?
- Intake ventilation
- Exhaust ventilation (Correct answer)
- Vapor barrier
- Air barrier
Correct answer: Exhaust ventilation
GAF Cobra® Ridge Vents are exhaust ventilation products installed at the ridge to allow hot, moist air to escape from the attic.
Question 4: What problem can result from having more exhaust ventilation capacity than intake ventilation capacity in an attic?
- Excessive moisture buildup
- Short-circuiting where air is pulled in through exhaust vents (Correct answer)
- Overheating of roof shingles
- Premature ridge vent corrosion
Correct answer: Short-circuiting where air is pulled in through exhaust vents
When exhaust exceeds intake, the system can short-circuit by drawing outside air back in through the exhaust vents rather than pulling it from the soffits.
Question 5: According to proper ventilation principles, what percentage of the total NFA should be allocated to intake vents versus exhaust vents?
- 25% intake, 75% exhaust
- 50% intake, 50% exhaust (Correct answer)
- 75% intake, 25% exhaust
- 60% intake, 40% exhaust
Correct answer: 50% intake, 50% exhaust
Best practice is a 50/50 balanced split between intake and exhaust net free area to ensure proper airflow through the attic.
Question 6: Which condition in an attic is most commonly caused by inadequate ventilation during winter months?
- Dry rot of rafters
- Ice dam formation (Correct answer)
- Excessive dust accumulation
- UV degradation of insulation
Correct answer: Ice dam formation
Inadequate attic ventilation in winter allows heat to escape through the roof deck, melting snow that refreezes at the cold eaves and forms ice dams.
Question 7: When installing a GAF ridge vent over a shingle roof, what must be cut along the ridge to allow proper airflow?
- A slot through the roof deck on both sides of the ridge (Correct answer)
- Holes in every rafter bay
- Removal of the ridge board
- Slots through only the shingles, not the deck
Correct answer: A slot through the roof deck on both sides of the ridge
A slot must be cut through the roof deck on each side of the ridge to create the opening that allows hot attic air to escape through the ridge vent.
GAF Ventilation & Attic Systems 1
What is the minimum net free area (NFA) of ventilation required per 150 square feet of attic floor space when there is no vapor barrier?