ICC Structural Wood Special Inspector
Examination Questions And Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
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Question 1
What is the minimum design value for the modulus of elasticity (E) for visually
graded Southern Pine No. 2 dimension lumber used in dry-service conditions per
the NDS?
A. 1.2 million psi
B. 1.4 million psi
C. 1.6 million psi
D. 1.8 million psi
Answer: C. 1.6 million psi
*Rationale: Per the NDS Supplement, the reference design value for modulus of
elasticity (E) for Southern Pine No. 2 is 1.6 million psi for dry-service conditions.
This value is used in deflection calculations and stability checks. Values of 1.2, 1.4,
and 1.8 million psi correspond to other species or grades, such as Hem-Fir No. 2
(1.2 million psi) or Douglas Fir-Larch No. 1 (1.8 million psi). The inspector must
verify that the specified grade and species match the design values on the
approved plans.
Question 2
During a framing inspection, you observe that the specified 3-inch-diameter bolts
in a wood-to-wood connection are installed with standard washers on both sides.
,What is the minimum edge distance required for the bolts if the member is loaded
parallel to grain and the bolt diameter is 3 inches?
A. 2.25 inches
B. 3.0 inches
C. 4.5 inches
D. 6.0 inches
Answer: C. 4.5 inches
*Rationale: NDS Table 12.5.1A requires a minimum edge distance for bolts loaded
parallel to grain of 1.5 times the bolt diameter for the loaded edge. For a 3-inch
bolt, 1.5 × 3 = 4.5 inches. Option A (2.25 inches) is the unloaded edge distance
requirement (0.75d). Option B is the bolt diameter itself, and Option D is the end
distance for tension members. The inspector must measure edge distances on site
to ensure compliance, as inadequate edge distance can lead to splitting or shear
failure.
Question 3
What is the maximum allowable hole diameter for a utility penetrations through a
solid sawn wood joist in the middle third of the span, per the International
Building Code (IBC)?
A. One-third of the joist depth
B. One-quarter of the joist depth
C. One-half of the joist depth
D. Two inches maximum regardless of depth
Answer: A. One-third of the joist depth
*Rationale: IBC Section 2308.8.2 permits holes bored in solid sawn joists in the
middle third of the span, provided the hole diameter does not exceed one-third of
the joist depth. Holes must be located at least 2 inches from the top and bottom
edges. Option B (one-quarter) applies to notches, not holes. Option C is incorrect
as it exceeds the allowable limit. The inspector should also verify that holes are not
located in the outer thirds of the span where shear stresses are highest.
,Question 4
In a glued-laminated timber (glulam) beam, what is the maximum allowable slope
of grain for the outer tension laminations in an appearance grade?
A. 1 in 8
B. 1 in 10
C. 1 in 12
D. 1 in 15
Answer: D. 1 in 15
*Rationale: ANSI A190.1 requires that the slope of grain in outer tension
laminations of glulam beams not exceed 1 in 15 for appearance grades. This
stringent requirement minimizes the risk of tension failure perpendicular to grain.
Options A (1 in 8) and B (1 in 10) are permitted for inner laminations or
compression zones. Option C (1 in 12) is sometimes used for less critical members.
The inspector should check mill certification reports for slope-of-grain
measurements.
Question 5
What is the minimum nominal thickness for a wood structural panel used as roof
sheathing with a span rating of 32/16 per the APA?
A. 3/8 inch
B. 7/16 inch
C. 1/2 inch
D. 5/8 inch
Answer: B. 7/16 inch
*Rationale: APA span rating 32/16 indicates the panel is rated for roof spans up to
32 inches and floor spans up to 16 inches. The minimum nominal thickness for this
rating is 7/16 inch for oriented strand board (OSB) or plywood. A 3/8-inch panel
does not meet the rating. While 1/2-inch and 5/8-inch panels are available, they
, are thicker than the minimum required. The inspector must verify that the stamp
on the panel matches the specified span rating and thickness.
Question 6
When inspecting a nailed wood-to-wood connection, what is the minimum
penetration depth for a common nail into the main member, per the NDS?
A. 6 times the nail diameter
B. 8 times the nail diameter
C. 10 times the nail diameter
D. 12 times the nail diameter
Answer: B. 8 times the nail diameter
*Rationale: NDS Section 12.1.5 requires that for laterally loaded nails, the
penetration into the main member must be at least 8 times the nail diameter. This
ensures adequate withdrawal and lateral resistance. Option A (6d) is insufficient
and would reduce capacity. Option C (10d) and Option D (12d) are conservative
but not the minimum required. The inspector should measure actual penetration,
especially in toe-nailed connections where full penetration is often difficult to
achieve.
Question 7
What is the allowable stress adjustment factor (C_D) for a wood member
subjected to a 10-day load duration under the NDS?
A. 1.00
B. 1.15
C. 1.25
D. 1.60
Answer: C. 1.25
*Rationale: NDS Table 2.3.2 provides load duration factors (C_D). For a 10-day
load duration (e.g., construction loads), C_D = 1.25. For permanent loads (>10
years), C_D = 1.00. For 7-day loads (snow), C_D = 1.15, and for impact loads, C_D =
Examination Questions And Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
Download Pdf
Question 1
What is the minimum design value for the modulus of elasticity (E) for visually
graded Southern Pine No. 2 dimension lumber used in dry-service conditions per
the NDS?
A. 1.2 million psi
B. 1.4 million psi
C. 1.6 million psi
D. 1.8 million psi
Answer: C. 1.6 million psi
*Rationale: Per the NDS Supplement, the reference design value for modulus of
elasticity (E) for Southern Pine No. 2 is 1.6 million psi for dry-service conditions.
This value is used in deflection calculations and stability checks. Values of 1.2, 1.4,
and 1.8 million psi correspond to other species or grades, such as Hem-Fir No. 2
(1.2 million psi) or Douglas Fir-Larch No. 1 (1.8 million psi). The inspector must
verify that the specified grade and species match the design values on the
approved plans.
Question 2
During a framing inspection, you observe that the specified 3-inch-diameter bolts
in a wood-to-wood connection are installed with standard washers on both sides.
,What is the minimum edge distance required for the bolts if the member is loaded
parallel to grain and the bolt diameter is 3 inches?
A. 2.25 inches
B. 3.0 inches
C. 4.5 inches
D. 6.0 inches
Answer: C. 4.5 inches
*Rationale: NDS Table 12.5.1A requires a minimum edge distance for bolts loaded
parallel to grain of 1.5 times the bolt diameter for the loaded edge. For a 3-inch
bolt, 1.5 × 3 = 4.5 inches. Option A (2.25 inches) is the unloaded edge distance
requirement (0.75d). Option B is the bolt diameter itself, and Option D is the end
distance for tension members. The inspector must measure edge distances on site
to ensure compliance, as inadequate edge distance can lead to splitting or shear
failure.
Question 3
What is the maximum allowable hole diameter for a utility penetrations through a
solid sawn wood joist in the middle third of the span, per the International
Building Code (IBC)?
A. One-third of the joist depth
B. One-quarter of the joist depth
C. One-half of the joist depth
D. Two inches maximum regardless of depth
Answer: A. One-third of the joist depth
*Rationale: IBC Section 2308.8.2 permits holes bored in solid sawn joists in the
middle third of the span, provided the hole diameter does not exceed one-third of
the joist depth. Holes must be located at least 2 inches from the top and bottom
edges. Option B (one-quarter) applies to notches, not holes. Option C is incorrect
as it exceeds the allowable limit. The inspector should also verify that holes are not
located in the outer thirds of the span where shear stresses are highest.
,Question 4
In a glued-laminated timber (glulam) beam, what is the maximum allowable slope
of grain for the outer tension laminations in an appearance grade?
A. 1 in 8
B. 1 in 10
C. 1 in 12
D. 1 in 15
Answer: D. 1 in 15
*Rationale: ANSI A190.1 requires that the slope of grain in outer tension
laminations of glulam beams not exceed 1 in 15 for appearance grades. This
stringent requirement minimizes the risk of tension failure perpendicular to grain.
Options A (1 in 8) and B (1 in 10) are permitted for inner laminations or
compression zones. Option C (1 in 12) is sometimes used for less critical members.
The inspector should check mill certification reports for slope-of-grain
measurements.
Question 5
What is the minimum nominal thickness for a wood structural panel used as roof
sheathing with a span rating of 32/16 per the APA?
A. 3/8 inch
B. 7/16 inch
C. 1/2 inch
D. 5/8 inch
Answer: B. 7/16 inch
*Rationale: APA span rating 32/16 indicates the panel is rated for roof spans up to
32 inches and floor spans up to 16 inches. The minimum nominal thickness for this
rating is 7/16 inch for oriented strand board (OSB) or plywood. A 3/8-inch panel
does not meet the rating. While 1/2-inch and 5/8-inch panels are available, they
, are thicker than the minimum required. The inspector must verify that the stamp
on the panel matches the specified span rating and thickness.
Question 6
When inspecting a nailed wood-to-wood connection, what is the minimum
penetration depth for a common nail into the main member, per the NDS?
A. 6 times the nail diameter
B. 8 times the nail diameter
C. 10 times the nail diameter
D. 12 times the nail diameter
Answer: B. 8 times the nail diameter
*Rationale: NDS Section 12.1.5 requires that for laterally loaded nails, the
penetration into the main member must be at least 8 times the nail diameter. This
ensures adequate withdrawal and lateral resistance. Option A (6d) is insufficient
and would reduce capacity. Option C (10d) and Option D (12d) are conservative
but not the minimum required. The inspector should measure actual penetration,
especially in toe-nailed connections where full penetration is often difficult to
achieve.
Question 7
What is the allowable stress adjustment factor (C_D) for a wood member
subjected to a 10-day load duration under the NDS?
A. 1.00
B. 1.15
C. 1.25
D. 1.60
Answer: C. 1.25
*Rationale: NDS Table 2.3.2 provides load duration factors (C_D). For a 10-day
load duration (e.g., construction loads), C_D = 1.25. For permanent loads (>10
years), C_D = 1.00. For 7-day loads (snow), C_D = 1.15, and for impact loads, C_D =
