Chicago DOB – Mason Contractor License
Examination Questions and Correct Answers
(Verified Answers) Plus Rationale 2027 Q&A|
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1. What is the primary purpose of mortar in a masonry wall?
A. To increase the weight of the wall
B. To provide insulation only
C. To bond masonry units, seal joints, and distribute loads
D. To replace reinforcement
Answer: C. To bond masonry units, seal joints, and distribute loads
Rationale: Mortar performs several important functions in masonry
construction. It bonds masonry units together, accommodates minor
dimensional variations, seals joints against air and water penetration,
and helps distribute compressive stresses between units.
2. Which masonry unit is most commonly manufactured from
Portland cement, aggregates, and water?
A. Clay brick
B. Concrete masonry unit
,C. Terra-cotta tile
D. Stone veneer
Answer: B. Concrete masonry unit
Rationale: A concrete masonry unit (CMU), commonly called a
concrete block, is manufactured primarily from cementitious
materials, aggregates, and water. CMUs are widely used for structural
and nonstructural walls.
3. What is the primary purpose of a mortar joint in a brick wall?
A. To make the brick waterproof
B. To provide a uniform bearing surface between units
C. To eliminate the need for flashing
D. To prevent all thermal movement
Answer: B. To provide a uniform bearing surface between units
Rationale: Mortar joints compensate for irregularities in masonry
units and provide a relatively uniform bearing surface. They also bond
the units and help control moisture and air movement through the
wall.
4. Which mortar type generally has the highest compressive
strength?
,A. Type K
B. Type O
C. Type N
D. Type M
Answer: D. Type M
Rationale: Type M mortar has the highest compressive strength
among the commonly specified ASTM mortar types. It is typically used
where high compressive strength is required, such as certain below-
grade or heavily loaded masonry applications.
5. Which mortar type is commonly selected for general-purpose
above-grade masonry?
A. Type N
B. Type K
C. Type M only
D. Type S only
Answer: A. Type N
Rationale: Type N is a commonly used general-purpose mortar for
above-grade masonry. It provides a balance of strength, workability,
and durability appropriate for many conventional masonry
applications.
, 6. What does the term “running bond” describe?
A. Bricks laid with every vertical joint aligned
B. Bricks laid with each course offset from the course below
C. Bricks placed only at corners
D. Bricks installed without mortar
Answer: B. Bricks laid with each course offset from the course below
Rationale: Running bond is one of the most common brick patterns.
Each masonry unit typically overlaps the units in the course below,
which improves the continuity and structural integrity of the wall.
7. What is a “header” in traditional brick masonry?
A. A brick laid with its short end or head exposed on the wall face
B. A horizontal steel beam
C. A mortar joint at the bottom of a wall
D. A vertical control joint
Answer: A. A brick laid with its short end or head exposed on the wall
face
Rationale: A header is traditionally a brick positioned so that its short
dimension is visible on the face of the wall. Headers can be used to
create bonding between wythes in certain masonry wall systems.
8. What is the purpose of a masonry “wythe”?
Examination Questions and Correct Answers
(Verified Answers) Plus Rationale 2027 Q&A|
Instant Download Pdf
1. What is the primary purpose of mortar in a masonry wall?
A. To increase the weight of the wall
B. To provide insulation only
C. To bond masonry units, seal joints, and distribute loads
D. To replace reinforcement
Answer: C. To bond masonry units, seal joints, and distribute loads
Rationale: Mortar performs several important functions in masonry
construction. It bonds masonry units together, accommodates minor
dimensional variations, seals joints against air and water penetration,
and helps distribute compressive stresses between units.
2. Which masonry unit is most commonly manufactured from
Portland cement, aggregates, and water?
A. Clay brick
B. Concrete masonry unit
,C. Terra-cotta tile
D. Stone veneer
Answer: B. Concrete masonry unit
Rationale: A concrete masonry unit (CMU), commonly called a
concrete block, is manufactured primarily from cementitious
materials, aggregates, and water. CMUs are widely used for structural
and nonstructural walls.
3. What is the primary purpose of a mortar joint in a brick wall?
A. To make the brick waterproof
B. To provide a uniform bearing surface between units
C. To eliminate the need for flashing
D. To prevent all thermal movement
Answer: B. To provide a uniform bearing surface between units
Rationale: Mortar joints compensate for irregularities in masonry
units and provide a relatively uniform bearing surface. They also bond
the units and help control moisture and air movement through the
wall.
4. Which mortar type generally has the highest compressive
strength?
,A. Type K
B. Type O
C. Type N
D. Type M
Answer: D. Type M
Rationale: Type M mortar has the highest compressive strength
among the commonly specified ASTM mortar types. It is typically used
where high compressive strength is required, such as certain below-
grade or heavily loaded masonry applications.
5. Which mortar type is commonly selected for general-purpose
above-grade masonry?
A. Type N
B. Type K
C. Type M only
D. Type S only
Answer: A. Type N
Rationale: Type N is a commonly used general-purpose mortar for
above-grade masonry. It provides a balance of strength, workability,
and durability appropriate for many conventional masonry
applications.
, 6. What does the term “running bond” describe?
A. Bricks laid with every vertical joint aligned
B. Bricks laid with each course offset from the course below
C. Bricks placed only at corners
D. Bricks installed without mortar
Answer: B. Bricks laid with each course offset from the course below
Rationale: Running bond is one of the most common brick patterns.
Each masonry unit typically overlaps the units in the course below,
which improves the continuity and structural integrity of the wall.
7. What is a “header” in traditional brick masonry?
A. A brick laid with its short end or head exposed on the wall face
B. A horizontal steel beam
C. A mortar joint at the bottom of a wall
D. A vertical control joint
Answer: A. A brick laid with its short end or head exposed on the wall
face
Rationale: A header is traditionally a brick positioned so that its short
dimension is visible on the face of the wall. Headers can be used to
create bonding between wythes in certain masonry wall systems.
8. What is the purpose of a masonry “wythe”?
