ICC 93 Tall Mass Timber Buildings Exam
with Practice Questions And Correct
Answers (Verif
1. Under ICC 93, a 12-story mass timber building uses exposed CLT floor panels. If
the required fire-resistance rating is 2 hours and the char rate for the CLT is 1.5
inches per hour, what minimum initial thickness must be provided to ensure a residual
cross-section after 2 hours of fire exposure? Assume no char contribution from the
adhesive and a 20% reduction for rounding.
A. 3.0 inches
B. 3.6 inches
C. 4.2 inches
D. 5.0 inches
Answer: B. 3.6 inches
Rationale: Char depth = 1.5 in/hr × 2 hr = 3.0 in. With 20% reduction for rounding,
required initial thickness = 3..8 = 3.75 in, rounded to 3.6 in per code. Options A, C,
and D misapply the reduction or ignore it entirely.
2. In a tall mass timber building with a CLT shear wall system, which seismic
force-resisting system is permitted under ICC 93 for structures over 6 stories?
A. Ordinary plain concrete shear walls
B. Special reinforced concrete shear walls
C. CLT shear walls with special detailing
D. Steel buckling-restrained braced frames
Answer: C. CLT shear walls with special detailing
Rationale: ICC 93 explicitly permits CLT shear walls with special detailing for tall mass
timber buildings, provided they meet ductility and overstrength requirements. Options A, B,
and D are either non-timber systems or not addressed in ICC 93 for this application.
Page 1 of 86
,3. A 10-story mass timber building uses glulam columns. To achieve a 1-hour
fire-resistance rating, which of the following is the most effective method according to
ICC 93?
A. Applying intumescent paint
B. Encapsulating with gypsum board
C. Using a sacrificial wood layer
D. Increasing column cross-section
Answer: B. Encapsulating with gypsum board
Rationale: ICC 93 recognizes encapsulation with gypsum board as a prescriptive method
for achieving fire-resistance ratings in mass timber. Intumescent paint is not a recognized
method, sacrificial wood is less common, and increasing cross-section alone does not
guarantee a rating.
4. For a CLT floor panel in a tall mass timber building, what is the primary purpose of
a concrete topping according to ICC 93?
A. To increase fire resistance
B. To improve acoustic performance
C. To provide composite action
D. To reduce deflection
Answer: B. To improve acoustic performance
Rationale: ICC 93 emphasizes acoustic separation in mass timber buildings, and a
concrete topping is often used to improve acoustic performance. While it can add mass and
reduce deflection, the primary code-driven purpose is acoustics.
Page 2 of 86
,5. In a performance-based design for a tall mass timber building, which parameter is
most critical for demonstrating equivalent fire safety to a prescriptive design?
A. Char rate of the timber
B. Time to flashover
C. Smoke development rate
D. Structural redundancy
Answer: A. Char rate of the timber
Rationale: The char rate directly determines the remaining structural capacity during a fire
and is fundamental to performance-based fire design. Other factors are important but
secondary to the char rate in structural fire engineering.
6. Which of the following connection details is most susceptible to moisture-induced
degradation in a tall mass timber building?
A. Steel plates with stainless steel bolts
B. Concealed steel angles in exterior walls
C. Galvanized steel brackets in interior dry areas
D. Aluminum connectors in conditioned spaces
Answer: B. Concealed steel angles in exterior walls
Rationale: Concealed steel angles in exterior walls are exposed to moisture and
temperature variations, leading to corrosion and potential degradation. Stainless steel and
galvanized options are more corrosion-resistant, and interior dry areas pose less risk.
Page 3 of 86
, 7. When designing a tall mass timber building for wind loads, which factor most
significantly affects the dynamic response?
A. Building mass
B. Damping ratio
C. Foundation type
D. Cladding type
Answer: B. Damping ratio
Rationale: The damping ratio critically influences the dynamic amplification of
wind-induced vibrations. Mass and stiffness affect frequency, but damping directly controls
response magnitude. Foundation and cladding have secondary effects.
8. In ICC 93, what is the maximum allowable height for a mass timber building with
an automatic sprinkler system and 2-hour fire-resistance-rated construction?
A. 120 feet
B. 180 feet
C. 270 feet
D. No limit
Answer: C. 270 feet
Rationale: ICC 93 permits heights up to 270 feet for mass timber buildings with sprinklers
and 2-hour ratings. Options A and B are lower limits for other construction types, and D is
incorrect as there are limits.
Page 4 of 86
with Practice Questions And Correct
Answers (Verif
1. Under ICC 93, a 12-story mass timber building uses exposed CLT floor panels. If
the required fire-resistance rating is 2 hours and the char rate for the CLT is 1.5
inches per hour, what minimum initial thickness must be provided to ensure a residual
cross-section after 2 hours of fire exposure? Assume no char contribution from the
adhesive and a 20% reduction for rounding.
A. 3.0 inches
B. 3.6 inches
C. 4.2 inches
D. 5.0 inches
Answer: B. 3.6 inches
Rationale: Char depth = 1.5 in/hr × 2 hr = 3.0 in. With 20% reduction for rounding,
required initial thickness = 3..8 = 3.75 in, rounded to 3.6 in per code. Options A, C,
and D misapply the reduction or ignore it entirely.
2. In a tall mass timber building with a CLT shear wall system, which seismic
force-resisting system is permitted under ICC 93 for structures over 6 stories?
A. Ordinary plain concrete shear walls
B. Special reinforced concrete shear walls
C. CLT shear walls with special detailing
D. Steel buckling-restrained braced frames
Answer: C. CLT shear walls with special detailing
Rationale: ICC 93 explicitly permits CLT shear walls with special detailing for tall mass
timber buildings, provided they meet ductility and overstrength requirements. Options A, B,
and D are either non-timber systems or not addressed in ICC 93 for this application.
Page 1 of 86
,3. A 10-story mass timber building uses glulam columns. To achieve a 1-hour
fire-resistance rating, which of the following is the most effective method according to
ICC 93?
A. Applying intumescent paint
B. Encapsulating with gypsum board
C. Using a sacrificial wood layer
D. Increasing column cross-section
Answer: B. Encapsulating with gypsum board
Rationale: ICC 93 recognizes encapsulation with gypsum board as a prescriptive method
for achieving fire-resistance ratings in mass timber. Intumescent paint is not a recognized
method, sacrificial wood is less common, and increasing cross-section alone does not
guarantee a rating.
4. For a CLT floor panel in a tall mass timber building, what is the primary purpose of
a concrete topping according to ICC 93?
A. To increase fire resistance
B. To improve acoustic performance
C. To provide composite action
D. To reduce deflection
Answer: B. To improve acoustic performance
Rationale: ICC 93 emphasizes acoustic separation in mass timber buildings, and a
concrete topping is often used to improve acoustic performance. While it can add mass and
reduce deflection, the primary code-driven purpose is acoustics.
Page 2 of 86
,5. In a performance-based design for a tall mass timber building, which parameter is
most critical for demonstrating equivalent fire safety to a prescriptive design?
A. Char rate of the timber
B. Time to flashover
C. Smoke development rate
D. Structural redundancy
Answer: A. Char rate of the timber
Rationale: The char rate directly determines the remaining structural capacity during a fire
and is fundamental to performance-based fire design. Other factors are important but
secondary to the char rate in structural fire engineering.
6. Which of the following connection details is most susceptible to moisture-induced
degradation in a tall mass timber building?
A. Steel plates with stainless steel bolts
B. Concealed steel angles in exterior walls
C. Galvanized steel brackets in interior dry areas
D. Aluminum connectors in conditioned spaces
Answer: B. Concealed steel angles in exterior walls
Rationale: Concealed steel angles in exterior walls are exposed to moisture and
temperature variations, leading to corrosion and potential degradation. Stainless steel and
galvanized options are more corrosion-resistant, and interior dry areas pose less risk.
Page 3 of 86
, 7. When designing a tall mass timber building for wind loads, which factor most
significantly affects the dynamic response?
A. Building mass
B. Damping ratio
C. Foundation type
D. Cladding type
Answer: B. Damping ratio
Rationale: The damping ratio critically influences the dynamic amplification of
wind-induced vibrations. Mass and stiffness affect frequency, but damping directly controls
response magnitude. Foundation and cladding have secondary effects.
8. In ICC 93, what is the maximum allowable height for a mass timber building with
an automatic sprinkler system and 2-hour fire-resistance-rated construction?
A. 120 feet
B. 180 feet
C. 270 feet
D. No limit
Answer: C. 270 feet
Rationale: ICC 93 permits heights up to 270 feet for mass timber buildings with sprinklers
and 2-hour ratings. Options A and B are lower limits for other construction types, and D is
incorrect as there are limits.
Page 4 of 86
