NASCLA Accredited Examination for Commercial General Building Contractors — Questions and Answers

Question 1: For spans, couple roof is used.

less than 5 m, but 2.5 m
less than 3.5 m (Correct answer)
less than 8 m, but 6.5 m
6 to 6.5 m but not less than

Correct answer: less than 3.5 m

A couple roof is a basic roof structure consisting of two rafters leaning against each other at the ridge and supported by the walls at the eaves. Due to its simple design and the outward thrust it exerts on the walls, it is only suitable for relatively small spans. Typically, couple roofs are used for spans less than 3.5 meters (approximately 11.5 feet).

Question 2: What is the standard thickness of plywood or OSB sheathing used for residential wall sheathing?

1/4 inch
3/8 inch
5/8 inch
7/16 to 1/2 inch (Correct answer)

Correct answer: 7/16 to 1/2 inch

7/16-inch OSB or 1/2-inch plywood is the most common thickness for exterior wall sheathing in residential wood-frame construction.

Question 3: In construction estimating, what is a 'quantity takeoff'?

A list of change orders
A bid submitted to a general contractor
The process of measuring and listing all materials needed from drawings (Correct answer)
A schedule of subcontractor payments

Correct answer: The process of measuring and listing all materials needed from drawings

A quantity takeoff (QTO) is the process of measuring and listing all materials, labor, and equipment quantities from construction drawings to prepare a cost estimate.

Question 4: The ________ could cause an arch to collapse.

Abutments that have settled unevenly
Crushing of the material
All of the options are correct (Correct answer)
Moving voussoirs

Correct answer: All of the options are correct

An arch can collapse due to several factors, making 'All of the options are correct' the right answer. Crushing of the material occurs if the compressive stress exceeds the arch's material strength. Uneven settlement of the abutments (the supports at the ends of the arch) can introduce differential forces, leading to instability. Lastly, moving voussoirs (the wedge-shaped stones or bricks forming the arch) indicate a loss of interlock or excessive movement, compromising the arch's structural integrity.

Question 5: What is the purpose of a 'legend' on a construction drawing?

To explain symbols, abbreviations, and line types used on the drawings (Correct answer)
To list the project team members
To list material specifications
To show the project schedule

Correct answer: To explain symbols, abbreviations, and line types used on the drawings

A legend (or symbol key) on a construction drawing identifies and explains all symbols, line types, abbreviations, and conventions used throughout the set.

Question 6: _______ refers to the lower half of the arch between the crown and skew back.

Spandril
Haunch (Correct answer)
Soffit
Springing

Correct answer: Haunch

The haunch of an arch refers to the lower portion of the arch, specifically the section located between the springing line (where the arch begins to curve upwards from its supports) and the crown (the highest point of the arch). This area is crucial for the arch's structural integrity, as it transfers the load to the abutments. Springing is the starting point, soffit is the underside, and spandril is the triangular space above the haunch.

Question 7: What is the minimum curing time for standard Portland cement concrete to achieve adequate strength?

3 days
7 days (Correct answer)
28 days
1 day

Correct answer: 7 days

Concrete should be cured for a minimum of 7 days for adequate strength development; however, the standard 28-day strength is used for design purposes.

Question 8: Choose two of the following to represent the widely used geophysical approach in civil engineering:

The seismic method (Correct answer)
Electrical resistivity method (Correct answer)
Wave method
Gravitational method

Correct answer: The seismic method

The seismic method and electrical resistivity method are two prominent geophysical techniques widely employed in civil engineering. The seismic method utilizes the propagation of seismic waves to investigate subsurface layers and their properties, while the electrical resistivity method measures the electrical resistance of subsurface materials to identify different soil and rock types, groundwater levels, and geological structures. Both provide valuable insights into ground conditions without extensive excavation.

Question 9: Which wire color is used for the grounding conductor in standard US residential wiring?

Red
White
Black
Green or bare copper (Correct answer)

Correct answer: Green or bare copper

Green insulated wire or bare copper conductor is the NEC-standard color code for equipment grounding conductors.

Question 10: Only after ____ days may the formwork on the underside of the slabs be removed.

14
12
5
7 (Correct answer)

Correct answer: 7

The removal time for formwork is critical and depends on the concrete's strength gain, which is influenced by factors like mix design, temperature, and curing. For the underside of concrete slabs, a minimum period of 7 days is generally recommended before formwork removal. This allows the concrete to achieve sufficient strength to safely support its own weight and any subsequent construction loads without excessive deflection or damage.

Question 11: When pulling wire through conduit, what material is commonly used to reduce friction?

Silicone spray
WD-40
Motor oil
Wire pulling lubricant (wire pulling gel) (Correct answer)

Correct answer: Wire pulling lubricant (wire pulling gel)

Wire pulling lubricant (pulling gel) is specifically designed to reduce friction without damaging wire insulation and is the industry-standard choice.

Question 12: _______ refers to the opening in a sloping roof whose top is parallel to the roof surface.

Dormer window
Lantern window
Sky light window (Correct answer)
Louvered window

Correct answer: Sky light window

A skylight window is an opening in a sloping roof designed to admit natural light and sometimes provide ventilation. Its top surface is typically installed parallel to the slope of the roof, allowing it to integrate seamlessly with the roofline. This design distinguishes it from other window types like dormers, which project vertically from a sloping roof.

Question 13: The Auger boring technique is inappropriate for _______.

Concrete soil
All of the options are correct (Correct answer)
Really tough soil
Vary soft soil

Correct answer: All of the options are correct

Auger boring is a soil exploration technique that uses a rotating helical screw to bring soil samples to the surface. While effective in many soil types, it is inappropriate for very soft soils where the borehole might collapse, extremely tough soils where the auger cannot penetrate effectively, or concrete soil as it is designed for natural soil, not hardened materials. In such conditions, other drilling methods are required.

Question 14: What is the minimum concrete cover required for rebar in a slab exposed to weather in the US?

1-1/2 inches (Correct answer)
3 inches
2 inches
3/4 inch

Correct answer: 1-1/2 inches

ACI 318 requires a minimum of 1-1/2 inches of concrete cover over reinforcing steel in slabs exposed to weather to protect against corrosion.

Question 15: For beams and slabs, concrete slump should range from ________.

30 to 125 mm (Correct answer)
40 to 100 mm
35 to 125 mm
45 to 100 mm

Correct answer: 30 to 125 mm

Concrete slump is a measure of its workability, indicating the consistency of the fresh concrete mix. For structural elements like beams and slabs, a slump range of 30 to 125 mm (approximately 1 to 5 inches) is generally recommended. This range ensures the concrete is workable enough to be placed and compacted effectively without excessive segregation, while still maintaining adequate strength and durability after hardening.

Question 16: What is 'engineered lumber' in construction framing?

Lumber graded by a licensed engineer
Pressure-treated lumber for ground contact
Manufactured wood products like LVL, PSL, and I-joists engineered for specific structural applications (Correct answer)
Reclaimed lumber repurposed for framing

Correct answer: Manufactured wood products like LVL, PSL, and I-joists engineered for specific structural applications

Engineered lumber (LVL, PSL, LSL, I-joists, glulam) is manufactured from wood components bonded together to achieve superior and predictable structural properties.

Question 17: What is 'cold joint' in concrete construction?

Cracking caused by temperature changes
A construction joint with no reinforcement
A joint between two separate concrete pours where the first set before the second was placed (Correct answer)
Concrete placed during cold weather

Correct answer: A joint between two separate concrete pours where the first set before the second was placed

A cold joint forms when fresh concrete is placed against previously hardened concrete, creating a plane of weakness due to poor bond at the interface.

Question 18: What is 'value engineering' in a construction project?

Engineering the exact market value of a building
Calculating ROI for construction investments
A systematic method to improve the value of a project by analyzing function vs. cost (Correct answer)
Adding premium finishes to increase property value

Correct answer: A systematic method to improve the value of a project by analyzing function vs. cost

Value engineering is a systematic approach to improving project value by identifying and eliminating unnecessary costs while maintaining required functions and quality.

Question 19: _______ refers to the outside angle between a wall's outer faces.

Junction
Quion (Correct answer)
All of the options are correct
Turn

Correct answer: Quion

A quoin (pronounced 'coin') refers to the external angle or corner of a wall or building. In masonry construction, quoins are often distinguished by being built of larger, dressed stones or bricks, or by being laid in a different pattern, to provide both structural strength and aesthetic emphasis to the corner.

Question 20: The minimal depth of foundations, according to Rankine's formula, is ______.

(P/w) × [(1 - sin φ)/(1 + sin φ)]² (Correct answer)
(P/w) × [(1 + sin φ)/(1 - sin φ)]²
(P/2w) × [(1 - sin φ)/(1 + sin φ)]²
(P/w) × [(1 + sin φ)/(1 - sin φ)]²

Correct answer: (P/w) × [(1 - sin φ)/(1 + sin φ)]²

Rankine's formula provides a theoretical minimum depth for foundations to ensure stability against lateral soil movement. The formula is Df = (P/w) × [(1 - sin φ)/(1 + sin φ)]², where Df is the minimum depth, P is the safe bearing capacity of the soil, w is the unit weight of the soil, and φ is the angle of repose or internal friction of the soil. This calculation helps prevent the soil from yielding laterally under the foundation's load.

Question 21: What type of electrical drawing shows the physical layout of equipment and wiring in a building?

Schematic diagram
Wiring plan (floor plan electrical drawing) (Correct answer)
One-line diagram
Riser diagram

Correct answer: Wiring plan (floor plan electrical drawing)

A wiring plan or floor plan electrical drawing shows the physical locations of outlets, switches, panels, and wiring paths as viewed from above.

Question 22: _______ is the main component in granite that gives stone its strength.

Granite
Mica
Quartz (Correct answer)
Felspar

Correct answer: Quartz

Quartz is the main component in granite that imparts significant strength and durability to the stone. As a very hard and crystalline mineral, quartz contributes to granite's high compressive strength, resistance to abrasion, and overall robustness, making it a highly valued material in construction.

Question 23: ________ refers to exposed vertical surfaces that are perpendicular to door or window frames.

Jambs
Soffits
Reveals (Correct answer)
Lintels

Correct answer: Reveals

Reveals refer to the exposed vertical surfaces of a wall opening, such as for a door or window, that are perpendicular to the frame. They are the visible parts of the jamb that lie between the outer face of the wall and the actual window or door frame. Reveals contribute to the architectural detailing and finish of an opening.

Question 24: _______ is a style of pointing in which the bottom of the mortar joints is flush with the face of the wall and the upper side is kept about 12 mm inside the face of the masonry.

Grooved pointing
Recessed pointing
Truck pointing
Struck pointing (Correct answer)

Correct answer: Struck pointing

Struck pointing is a specific type of mortar joint finish designed for both aesthetics and weather resistance. In this style, the bottom edge of the mortar joint is flush with the wall's face, while the upper edge is recessed inwards, typically by about 12 mm. This creates a sloped surface that effectively sheds rainwater away from the joint, preventing water penetration and enhancing durability.

Question 25: An existing structure's stability could be compromised by _______.

Increasing water table
The tremors brought generated by traffic movements
Mining nearby.
All of the options are correct (Correct answer)

Correct answer: All of the options are correct

The stability of an existing structure can be severely compromised by various external factors. Nearby mining operations can cause ground settlement or subsidence, while tremors from traffic movements can induce vibrations and fatigue in the structure. Additionally, an increasing water table can reduce soil bearing capacity, cause uplift pressures, or lead to soil liquefaction, all of which threaten foundation and structural integrity.

Question 26: The term "_________" typically refers to the inside portion of a cavity wall.

Pillar
Buttress
Leaf wall (Correct answer)
Pilaster

Correct answer: Leaf wall

A cavity wall is constructed with two separate walls, or 'leaves,' separated by an air gap (cavity). The inner wall, which forms the internal face of the building, is commonly referred to as the 'inner leaf' or simply 'leaf wall.' This design is effective for improving thermal insulation, sound insulation, and preventing dampness penetration.

Question 27: The depth of exploration for each floor (or storey) of a building should be _______.

10 meters
1 meter
12 meters
3 meters (Correct answer)

Correct answer: 3 meters

The depth of soil exploration for a building's foundation is critical for understanding the subsurface conditions. A common guideline for preliminary investigations suggests a minimum exploration depth of 3 meters for each floor or storey of the building. This ensures that the investigation extends sufficiently below the proposed foundation level to identify any problematic soil layers, groundwater, or geological features that could affect the structure.

Question 28: ______ is the process of maintaining moisture in finished concrete for a set amount of time.

Curing of concrete (Correct answer)
Compaction of concrete
Placing of concrete
Finishing of concrete

Correct answer: Curing of concrete

Curing of concrete is the essential process of maintaining adequate moisture content and a favorable temperature in freshly placed concrete for a specific period. This allows the cement to fully hydrate, which is crucial for the concrete to develop its intended strength, durability, and other desired engineering properties. Proper curing prevents premature drying and ensures optimal performance.

Question 29: Which drawing type shows the vertical cross-section of a building cut from top to bottom?

Detail view
Section view (Correct answer)
Plan view
Elevation view

Correct answer: Section view

A section view shows a vertical cut through the building, revealing interior construction details, floor-to-floor heights, and material layers.

Question 30: The wedge-shaped bricks used to create the arch ring are known as

Voussoirs (Correct answer)
Spandrils
Haunches
Soffits

Correct answer: Voussoirs

Voussoirs are the fundamental components of an arch. They are precisely cut, wedge-shaped blocks, usually made of stone or brick, that form the curved structure. These blocks are arranged with radiating joints, transferring the compressive forces of the arch outwards to its supports, with the central keystone locking them into place.

Question 31: Dado is typically offered in _______.

Living rooms
Balcony
Bath rooms (Correct answer)
Garage

Correct answer: Bath rooms

Dado is a decorative and protective finish applied to the lower portion of a wall, typically extending up to a height of 90-120 cm. It is most commonly offered in bathrooms and kitchens because it provides a durable, easily cleanable surface that protects the walls from splashes, moisture, and general wear and tear, while also adding an aesthetic element to the room.

Question 32: What does a dashed (hidden) line represent on a construction drawing?

A property line
A demolished element
An element hidden from the current view (Correct answer)
A future addition

Correct answer: An element hidden from the current view

Hidden lines (dashed) represent edges, surfaces, or features that exist but are not directly visible from the current viewing direction.

Question 33: What is required before work begins in a confined space on a construction site?

A permit and atmospheric testing (Correct answer)
A supervisor sign-off only
A written safety plan only
A weekly safety meeting

Correct answer: A permit and atmospheric testing

OSHA 29 CFR 1926.1203 requires a permit and atmospheric testing before entry into permit-required confined spaces on construction sites.

Question 34: _______ is the form of foundation that is typically offered in soils with poor bearing capacity.

All of the options are correct (Correct answer)
Grillage footing
Column footing
Raft footing

Correct answer: All of the options are correct

In soils with poor bearing capacity, foundations are designed to distribute the building's load over a larger area to reduce pressure on the soil. Grillage footings use a network of steel beams, and raft (or mat) footings are large concrete slabs covering the entire building footprint, both effectively spreading the load. While column footings alone might not suffice, when designed as large spread footings or integrated into a system like a raft, they also contribute to load distribution. Therefore, all listed options represent forms of foundation typically considered for poor bearing capacity soils.

Question 35: What is the purpose of rebar (reinforcing steel) in concrete?

To increase concrete's compressive strength
To speed up the curing process
To reduce the amount of cement needed
To resist tensile stresses that concrete cannot handle (Correct answer)

Correct answer: To resist tensile stresses that concrete cannot handle

Concrete is strong in compression but weak in tension; rebar is embedded to carry tensile forces and prevent cracking under loads.

Question 36: With a _________, foundation excavation depth is often measured.

Boning rod (Correct answer)
Steel tape
Levelling staff
Ranging rod

Correct answer: Boning rod

A boning rod is a T-shaped tool used in conjunction with sight rails to accurately establish and check the correct depth and level of excavations, particularly for foundations and trenches. It allows construction workers to precisely transfer levels from known reference points, ensuring the excavation is dug to the required depth and gradient.

Question 37: How far must a ladder extend above the landing surface when used to access an elevated work area?

1 foot
2 feet
3 feet (Correct answer)
5 feet

Correct answer: 3 feet

OSHA requires portable ladders to extend at least 3 feet above the landing surface they are used to access.

Question 38: What scale is most commonly used for architectural floor plan drawings?

1" = 10'-0"
1/8" = 1'-0"
1/2" = 1'-0"
1/4" = 1'-0" (Correct answer)

Correct answer: 1/4" = 1'-0"

The most common scale for architectural floor plans is 1/4 inch equals 1 foot, providing enough detail while fitting on standard sheet sizes.

Question 39: A minimum 15 cm cover is supplied on the ______ in grillage foundations.

All options are incorrect
The outside beams' ends
Exterior beams' ends
Lower beam of lower tier (Correct answer)

Correct answer: Lower beam of lower tier

Grillage foundations consist of a network of steel beams embedded in concrete, designed to distribute heavy column loads over a large area of soil. To protect these steel beams from corrosion and ensure proper load transfer, a minimum concrete cover is required. Specifically, the lower beam of the lower tier, which is closest to the soil, needs a minimum cover of 15 cm (or 6 inches) to provide adequate protection.

Question 40: What is the OSHA permissible exposure limit (PEL) for noise over an 8-hour workday?

85 dBA
95 dBA
90 dBA (Correct answer)
80 dBA

Correct answer: 90 dBA

OSHA 29 CFR 1926.52 sets the permissible noise exposure limit at 90 dBA for an 8-hour workday.

Question 41: When calculating square footage for a concrete slab, which formula is used?

Pi × Radius²
Length × Width × Height
Length + Width × 2
Length × Width (Correct answer)

Correct answer: Length × Width

Square footage is calculated by multiplying length by width (L × W), giving the area in square feet; volume requires multiplying by thickness.

Question 42: When must a Safety Data Sheet (SDS) be accessible to workers on a construction site?

Only upon request
Only during chemical spills
At all times during work shifts (Correct answer)
Once per week

Correct answer: At all times during work shifts

OSHA's HazCom Standard requires SDS documents to be readily accessible to workers at all times during their work shift.

Question 43: _______ is the point at which the surfaces of a sloping roof intersect and produce an exterior angle greater than 180 degrees.

Valley
Ridge
All of the options are incorrect
Hip (Correct answer)

Correct answer: Hip

A hip is the external angle formed by the intersection of two sloping roof surfaces that meet at an angle greater than 180 degrees. It runs from the ridge (the highest horizontal line) down to the eaves. In contrast, a valley forms an internal angle, and a ridge is the horizontal line at the apex of a roof.

Question 44: What is the required lateral distance from an excavation for spoil pile placement per OSHA?

2 feet (Correct answer)
1 foot
3 feet
5 feet

Correct answer: 2 feet

OSHA 29 CFR 1926.651 requires excavated material (spoil) to be placed at least 2 feet from the edge of the excavation.

Question 45: What is the standard size of a modular brick in the United States?

4" × 2-2/3" × 8"
3-1/2" × 2-1/2" × 7-1/2"
3" × 2" × 8"
3-5/8" × 2-1/4" × 7-5/8" (Correct answer)

Correct answer: 3-5/8" × 2-1/4" × 7-5/8"

A standard modular brick measures 3-5/8 inches wide × 2-1/4 inches tall × 7-5/8 inches long, which equals 4" × 2-2/3" × 8" with mortar joints.

Question 46: In construction scheduling, what is a 'critical path'?

The safest route through a job site
The order in which inspections occur
The path emergency vehicles use on site
The longest sequence of dependent tasks that determines project duration (Correct answer)

Correct answer: The longest sequence of dependent tasks that determines project duration

The critical path is the longest sequence of dependent activities that determines the minimum project completion time; any delay on the critical path delays the entire project.

Question 47: To achieve strong bonding when masonry bricks,

Alternate courses' vertical junctions are maintained plumb.
High-quality bricks are used.
Bats are used when necessary.
All of the options are correct (Correct answer)

Correct answer: All of the options are correct

Achieving strong bonding in masonry requires a combination of good practices. Using high-quality bricks ensures the material itself is robust. Maintaining plumb vertical junctions in alternate courses (e.g., in English or Flemish bond) is crucial for structural stability and proper load distribution. Lastly, bats (half bricks) are essential for creating staggered joints and avoiding continuous vertical lines, which would significantly weaken the wall.

Question 48: The capacity of granite to support weight is typically _________.

40 to 45 kg/cm²
30 to 35 kg/cm² (Correct answer)
42 to 46 kg/cm²
15 to 20 kg/cm²

Correct answer: 30 to 35 kg/cm²

Granite is a very dense, strong, and durable igneous rock, making it an excellent material for foundations and structural elements. Its high compressive strength allows it to support significant loads without crushing. The typical bearing capacity of granite ranges from 30 to 35 kg/cm² (approximately 3000 to 3500 kN/m²), which is considerably higher than most other natural stones or soils.

Question 49: What is the 'rise over run' in roof framing terminology?

The total roof height over total building width
The ratio of roof span to eave height
The vertical rise in inches for every 12 inches of horizontal run — the roof pitch (Correct answer)
The angle of the rafter cut at the ridge

Correct answer: The vertical rise in inches for every 12 inches of horizontal run — the roof pitch

Roof pitch (rise over run) expresses how many inches the roof rises vertically for every 12 inches of horizontal run, such as 6:12 or 8:12.

Question 50: Which document serves as the primary standard for electrical installations in construction in the United States?

NFPA 70 (National Electrical Code) (Correct answer)
IEEE Standard 141
OSHA 1926 Subpart K
ANSI C2 (NESC)

Correct answer: NFPA 70 (National Electrical Code)

NFPA 70, the National Electrical Code (NEC), is the primary standard adopted by most US jurisdictions governing safe electrical installations in buildings.

Question 51: Which type of wood joint uses a toothed metal plate connector pressed into both wood members at a truss joint?

Truss plate (Gang-nail plate) (Correct answer)
Pocket screw joint
Mortise and tenon
Lap joint

Correct answer: Truss plate (Gang-nail plate)

Metal truss plates (gang-nail plates) are toothed metal connector plates pressed into lumber at truss joints to create engineered connections in prefabricated roof and floor trusses.

Question 52: _______ are construction windows that extend outside a room to let in extra light and air.

Lantern window
Bay window (Correct answer)
Dormer window
Casement window

Correct answer: Bay window

A mullion is a vertical element that runs through the center of a shutter frame, or any window or door frame, dividing the panes or panels. It provides structural support and defines the individual sections of the shutter, contributing to its overall rigidity and aesthetic design.

Question 53: What does the designation 'f'c = 4000 psi' mean for concrete?

The specified compressive strength at 28 days is 4000 psi (Correct answer)
The concrete weighs 4000 psi
The tensile strength is 4000 psi
The concrete must be placed at 4000 psi pressure

Correct answer: The specified compressive strength at 28 days is 4000 psi

f'c denotes the specified compressive strength of concrete measured in pounds per square inch (psi) at 28 days after placement.

Question 54: In stair framing, what is the 'rise' and 'run'?

Rise is the horizontal depth of the tread; run is the vertical height of the riser
Rise is the vertical height of each step; run is the horizontal depth of each tread (Correct answer)
Rise is the stair angle; run is the stringer length
Rise is total stair height; run is total stair length

Correct answer: Rise is the vertical height of each step; run is the horizontal depth of each tread

In stair design, rise is the vertical height of each individual step (riser) and run is the horizontal depth of each tread.

Question 55: What is the purpose of a 'vapor barrier' under a concrete slab on grade?

To reinforce the bottom of the slab
To prevent ground moisture from migrating up through the slab (Correct answer)
To act as a slip sheet during concrete placement
To insulate the slab from ground temperature

Correct answer: To prevent ground moisture from migrating up through the slab

A vapor barrier (typically polyethylene sheeting) is placed under slabs on grade to prevent ground moisture from rising through the concrete and damaging flooring above.

Question 56: Which OSHA standard governs the use of personal protective equipment (PPE) on construction sites?

29 CFR 1926.100 (Correct answer)
29 CFR 1910.132
29 CFR 1926.200
29 CFR 1926.50

Correct answer: 29 CFR 1926.100

OSHA 29 CFR 1926.100 covers head protection and PPE requirements specific to construction.

Question 57: What is the standard voltage for most residential electrical service in the United States?

277/480V three-phase
240/480V single-phase
120/240V single-phase (Correct answer)
120/208V three-phase

Correct answer: 120/240V single-phase

Standard US residential service is 120/240V single-phase, providing 120V for outlets and 240V for large appliances.

Question 58: _______ is a type of mortar that uses both cement and lime as binding agents.

Fire resistant mortar
Cement mortar
Lime mortar
Gauged mortar (Correct answer)

Correct answer: Gauged mortar

Gauged mortar is a versatile type of mortar that combines both cement and lime as binding agents, along with sand and water. The inclusion of cement enhances the mortar's strength and accelerates its setting time, while lime improves its workability, plasticity, and water retention. This combination provides a balanced set of desirable properties for various masonry applications.

Question 59: How frequently must fire extinguishers on a construction site be visually inspected?

Daily
Weekly
Quarterly
Monthly (Correct answer)

Correct answer: Monthly

OSHA and NFPA 10 require fire extinguishers to be visually inspected monthly to ensure they are charged and accessible.

Question 60: What type of fire extinguisher should be used on an electrical fire on a construction site?

Class D
Class A
Class B
Class C (Correct answer)

Correct answer: Class C

Class C fire extinguishers use non-conductive agents and are required for electrical fires to prevent electrocution.

Question 61: What is the maximum voltage drop recommended by the NEC for branch circuits to minimize energy loss and equipment performance issues?

1%
10%
5%
3% (Correct answer)

Correct answer: 3%

The NEC recommends a maximum 3% voltage drop for branch circuits to maintain efficient equipment operation and prevent overheating from excess current draw.

Question 62: What is the minimum clearance required between the top of a residential electrical panel and the ceiling?

6.5 feet (Correct answer)
No minimum required
6 feet
3 feet

Correct answer: 6.5 feet

NEC 110.26 requires a minimum dedicated headroom of 6.5 feet (78 inches) above electrical equipment to ensure safe working space.

Question 63: _______ is the style of arch utilized in high-end structures where aesthetics are crucial.

Ashlar arch (Correct answer)
Rubble arch
Gauged brick arch
Axed brick arch

Correct answer: Ashlar arch

An ashlar arch is constructed using finely dressed and accurately cut stones, known as ashlar masonry. These arches are characterized by their precise workmanship, smooth surfaces, and uniform, thin joints. Due to their superior finish and aesthetic appeal, ashlar arches are typically chosen for high-end structures where visual quality and architectural elegance are paramount.

Question 64: The mortar used in load-bearing brick masonry must have a minimum strength of _______.

250 N/cm²
100 N/cm² (Correct answer)
200 N/cm²
220 N/cm²

Correct answer: 100 N/cm²

For load-bearing brick masonry, the mortar must possess sufficient compressive strength to effectively transfer loads and ensure the stability of the structure. A minimum compressive strength of 100 N/cm² (or 10 MPa) is a common requirement specified in building codes and standards. This ensures the mortar can withstand the applied stresses without crushing, maintaining the integrity of the masonry.

Question 65: Which of the following is NOT a type of cave-in protection system recognized by OSHA for excavations?

Sloping
Trench boxes
Drainage matting (Correct answer)
Shoring

Correct answer: Drainage matting

OSHA recognizes sloping, shoring, and trench shields (boxes) as acceptable cave-in protection systems; drainage matting is not a recognized method.

Question 66: When drilling in ________, rotary drilling is the fastest method.

Rocky soils
All of these (Correct answer)
Clay soils
Sandy soil

Correct answer: All of these

Rotary drilling is a highly versatile and efficient method for creating boreholes in a wide range of geological conditions. It operates by rotating a cutting bit that grinds or shears through the material, making it effective in various soil types including soft clay, loose sandy soil, and even hard rocky soils. Its adaptability and speed make it a preferred choice for many drilling applications.

Question 67: What is the purpose of a 'bonding jumper' in an electrical system?

To connect two separate electrical panels together
To balance load across two legs of service
To ensure electrical continuity between metal parts of a system that may otherwise be isolated (Correct answer)
To reduce voltage drop over long wire runs

Correct answer: To ensure electrical continuity between metal parts of a system that may otherwise be isolated

A bonding jumper ensures all metal enclosures and raceways are electrically connected, providing a low-impedance fault path and preventing dangerous voltage differences.

Question 68: What is the purpose of control joints in a concrete slab?

To provide locations where cracking can occur in a controlled manner (Correct answer)
To increase the slab's load capacity
To accommodate pipe penetrations
To allow expansion due to heat

Correct answer: To provide locations where cracking can occur in a controlled manner

Control joints create weakened planes in concrete slabs that guide shrinkage cracking to occur at planned locations rather than randomly across the slab.

Question 69: Which test is used to measure the compressive strength of hardened concrete cylinders?

Slump test
Cylinder compression test (ASTM C39) (Correct answer)
Kelly ball test
Air content test

Correct answer: Cylinder compression test (ASTM C39)

ASTM C39 is the standard test method for compressive strength of cylindrical concrete specimens, typically 4×8 or 6×12 inch cylinders tested at 28 days.

Question 70: What does the term 'ampacity' refer to in electrical construction?

The resistance of a conductor per foot
The total wattage a circuit can handle
The voltage capacity of a conductor
The maximum current a conductor can carry continuously without exceeding its temperature rating (Correct answer)

Correct answer: The maximum current a conductor can carry continuously without exceeding its temperature rating

Ampacity is the maximum current in amperes a conductor can continuously carry under specific conditions without exceeding its insulation temperature rating.

Question 71: In roof framing, what is the 'ridge board' or 'ridge beam'?

The bottom chord of a roof truss
The blocking between rafters
The horizontal member at the peak of a sloped roof (Correct answer)
The fascia board at the roof edge

Correct answer: The horizontal member at the peak of a sloped roof

The ridge board is the horizontal member running along the peak of a sloped roof to which the tops of common rafters are fastened.

Question 72: ______ are the protrusions on a door or window frame's head or sill.

Transoms
Chocks
Stops
Horns (Correct answer)

Correct answer: Horns

Horns are the extensions of the head or sill of a door or window frame that project beyond the jambs. These protrusions are typically left on the frame during manufacturing to provide a secure grip and facilitate proper fixing into the wall opening. They are often trimmed flush with the wall after the frame has been securely installed.

Question 73: What type of mortar joint is most water-resistant and recommended for exterior masonry?

Struck joint
Raked joint
Concave (tooled) joint (Correct answer)
Flush joint

Correct answer: Concave (tooled) joint

A concave (tooled) joint is the most weather-resistant mortar joint because the tooling compresses and seals the mortar surface, preventing water infiltration.

Question 74: What is 'blocking' in wood frame construction?

Horizontal pieces of lumber installed between framing members for support, fire stopping, or backing (Correct answer)
Installing temporary bracing during construction
Sealing gaps in the wall assembly
The process of squaring wall frames before sheathing

Correct answer: Horizontal pieces of lumber installed between framing members for support, fire stopping, or backing

Blocking refers to pieces of lumber installed horizontally between studs, joists, or rafters to provide support for fixtures, prevent fire spread, or limit racking.

Question 75: What does 'on center' (OC) mean in framing dimensions?

The measurement from the center of one framing member to the center of the adjacent member (Correct answer)
The distance from the wall center to the exterior face
The measurement from the outside face of one member to the outside face of the next
The total distance across the framing system

Correct answer: The measurement from the center of one framing member to the center of the adjacent member

On center (OC) refers to the distance measured from the center of one framing member to the center of the next parallel member.

Question 76: What is the 'span' of a floor joist?

The horizontal distance between bearing points (supports) for the joist (Correct answer)
The spacing between adjacent joists
The length of the joist plus overhang
The depth of the joist member

Correct answer: The horizontal distance between bearing points (supports) for the joist

Joist span is the clear horizontal distance between the supports (typically foundation wall, beam, or bearing wall) that carry the joist's load.

Question 77: _______ is made from marble chips that range in size from 4 to 6 mm.

Granite floor
Marble floor
Reinforced marble floor
Terrazzo floor (Correct answer)

Correct answer: Terrazzo floor

Terrazzo flooring is a composite material renowned for its durability and aesthetic appeal. It is typically made by mixing chips of marble, quartz, granite, or glass, often ranging in size from 4 to 6 mm, with a cementitious or polymeric binder. This mixture is then poured, cured, ground, and polished to create a smooth, seamless, and decorative surface.

Question 78: What is the standard spacing for wall studs in residential wood-frame construction in the US?

16 inches on center (Correct answer)
24 inches on center
12 inches on center
32 inches on center

Correct answer: 16 inches on center

Standard residential wall framing uses 2×4 or 2×6 studs spaced 16 inches on center, though 24-inch spacing is also permitted by code for some applications.

Question 79: What is the function of a transformer in a construction project's temporary power distribution?

To convert single-phase to three-phase power
To change voltage levels from one value to another (Correct answer)
To protect circuits from overloads
To measure total electrical consumption on the site

Correct answer: To change voltage levels from one value to another

A transformer steps up or steps down AC voltage using electromagnetic induction, allowing utility high voltage to be reduced to usable construction site voltages.

Question 80: What lumber grade is commonly used for structural wall framing in residential construction?

No. 1
Select Structural
Utility Grade
No. 2 (Correct answer)

Correct answer: No. 2

No. 2 grade lumber (or Stud grade for walls) is the most commonly specified and economically available grade for structural wall, floor, and roof framing.

Question 81: What is the purpose of a slump test for concrete?

To check for air entrainment content
To measure the workability and consistency of fresh concrete (Correct answer)
To measure concrete compressive strength
To determine aggregate size distribution

Correct answer: To measure the workability and consistency of fresh concrete

The slump test measures the workability (flowability) of fresh concrete by measuring how much a cone of concrete settles after the cone mold is removed.

Question 82: Which AWG wire size is commonly used for a 20-amp, 120-volt branch circuit?

10 AWG
12 AWG (Correct answer)
8 AWG
14 AWG

Correct answer: 12 AWG

12 AWG copper wire has an ampacity of 20 amps and is the NEC-required minimum size for 20-amp branch circuits.

Question 83: What is the purpose of a toolbox talk on a construction site?

Brief safety meeting focusing on specific hazards (Correct answer)
Tool inventory management
Equipment maintenance scheduling
Work performance reviews

Correct answer: Brief safety meeting focusing on specific hazards

Toolbox talks are short, informal safety meetings held at the job site to discuss specific hazards related to the day's work activities.

Question 84: What is 'efflorescence' on masonry walls?

Cracking due to settlement
A decorative masonry pattern
A type of mortar joint finish
White salt deposits on the masonry surface caused by water migration (Correct answer)

Correct answer: White salt deposits on the masonry surface caused by water migration

Efflorescence is a white powdery deposit on masonry surfaces caused by water-soluble salts being carried to the surface and left behind as the water evaporates.

Question 85: What is the required clearance distance for equipment operating near overhead power lines rated up to 50 kV?

15 feet
10 feet (Correct answer)
5 feet
20 feet

Correct answer: 10 feet

OSHA 29 CFR 1926.1408 requires a minimum 10-foot clearance from overhead power lines rated up to 50 kV.

Question 86: On a site plan, what does a contour line represent?

Underground utility
Property boundary
Drainage direction
Line of equal elevation (Correct answer)

Correct answer: Line of equal elevation

Contour lines on a site plan connect points of equal elevation, allowing readers to visualize the terrain's slope and topography.

Question 87: A brick known as a _______ is typically used at the end of a course of bricks to stagger vertical joints in succeeding courses of a wall.

Bat
Stretcher
Closer (Correct answer)
Header

Correct answer: Closer

A closer is a brick that is cut or manufactured to a specific size, typically a quarter or half brick, and is inserted at the end of a course. Its primary purpose is to adjust the length of the course, ensuring that the vertical joints (perpends) in adjacent courses are staggered. This staggering, known as bonding, is crucial for distributing loads, enhancing the wall's strength, and preventing continuous vertical cracks.

Question 88: Choose one of the following to represent the false statement:

Concrete with a high early strength is typically utilized in cold climates.
The walls are pointed with lime surkhi mortar.
The only purpose of adding cement to lime mortar is to improve its hydraulic qualities. (Correct answer)
Before making lime mortar, lime should be slaked.

Correct answer: The only purpose of adding cement to lime mortar is to improve its hydraulic qualities.

The statement is false because adding cement to lime mortar, creating gauged mortar, serves multiple purposes beyond just improving its hydraulic qualities. Cement significantly increases the mortar's compressive strength and accelerates its setting time. While it does enhance hydraulic properties (ability to set underwater), it also improves overall strength, durability, and reduces shrinkage, making the mortar more robust for various construction applications.

Question 89: What is the maximum weight capacity of a standard single-width scaffold plank used in construction?

75 lbs/sq ft
50 lbs/sq ft (Correct answer)
100 lbs/sq ft
25 lbs/sq ft

Correct answer: 50 lbs/sq ft

OSHA requires scaffold planks to support at least 4 times the intended load, with standard platforms rated for 50 lbs per square foot.

Question 90: _______ is the practice of using screeds to level a floor to a real level surface.

Topping
Bedding
Screeding (Correct answer)
Bedding

Correct answer: Screeding

Screeding is the practice of leveling a freshly laid concrete or mortar surface, typically a floor, using a long, straight edge known as a screed board or screed bar. This process ensures that the surface achieves the desired flatness and levelness, creating a smooth and even base for subsequent floor finishes.

Question 91: What is a 'submittals' package in construction?

Weekly progress reports
Permit applications to the building department
Documents provided by contractors to confirm materials and methods meet specifications (Correct answer)
Final payment applications

Correct answer: Documents provided by contractors to confirm materials and methods meet specifications

Submittals are shop drawings, product data, and samples provided by contractors to the architect/engineer for review and approval before materials are procured or installed.

Question 92: Which view on a blueprint shows a building as seen from the outside at eye level?

Section view
Plan view
Detail view
Elevation view (Correct answer)

Correct answer: Elevation view

Elevation views show the exterior or interior faces of a building from a horizontal vantage point, typically labeled North, South, East, and West.

Question 93: What is the minimum height at which fall protection is required for workers on construction sites under OSHA standards?

8 feet
10 feet
4 feet
6 feet (Correct answer)

Correct answer: 6 feet

OSHA 29 CFR 1926.502 requires fall protection for construction workers at heights of 6 feet or more above a lower level.

Question 94: What is the purpose of air entrainment in concrete mixes used in freeze-thaw climates?

To speed up curing time
To create microscopic air bubbles that relieve freeze-thaw pressure (Correct answer)
To reduce the weight of concrete
To increase compressive strength

Correct answer: To create microscopic air bubbles that relieve freeze-thaw pressure

Air-entrained concrete contains microscopic air bubbles that provide relief space for water expansion during freezing, preventing surface scaling and cracking.

Question 95: According to NEC Article 210, what is the required height range for installing standard 15- or 20-amp receptacles in a commercial wall installation?

At least 6 inches from the floor
No specific height requirement — follow local code and architectural plans (Correct answer)
Between 36 and 48 inches from the floor
Exactly 18 inches from the floor

Correct answer: No specific height requirement — follow local code and architectural plans

The NEC does not specify a fixed mounting height for standard receptacles in commercial spaces; height is determined by local codes, ADA requirements, and architectural plans.

Question 96: Under OSHA regulations, how often must a competent person inspect an excavation?

Before each work shift (Correct answer)
Only after rain events
Once per week
Every 4 hours

Correct answer: Before each work shift

OSHA 29 CFR 1926.651(k) requires a competent person to inspect excavations before each work shift and as needed.

Question 97: What type of footing is typically used for a single column load?

Strip footing
Grade beam
Spread (pad) footing (Correct answer)
Mat footing

Correct answer: Spread (pad) footing

A spread footing (also called a pad footing) is an isolated square or rectangular footing designed to distribute a single column load to the soil.

Question 98: Choose the appropriate statement from the list below:

Both compression and tension are equally powerful forces for plain cement concrete.
The index value known as fineness modulus expresses the relative sizes of both coarse and fine aggregates. (Correct answer)
Curing concrete is necessary for optimal cement compaction.
Slump test is used to evaluate the strength of concrete.

Correct answer: The index value known as fineness modulus expresses the relative sizes of both coarse and fine aggregates.

The fineness modulus is an empirical index value used in concrete technology to describe the average size of aggregate particles. It is derived from the sieve analysis of both coarse and fine aggregates, providing a quick measure of their overall fineness or coarseness. This value is crucial for concrete mix design, helping to ensure optimal workability, strength, and economy of the mix.

Question 99: What is the purpose of a load center (electrical panel) in a building?

To convert AC power to DC power for appliances
To distribute electrical power to branch circuits and provide overcurrent protection (Correct answer)
To step down utility voltage to usable levels
To monitor and record electrical usage for billing

Correct answer: To distribute electrical power to branch circuits and provide overcurrent protection

A load center distributes incoming electrical service into individual branch circuits, each protected by a breaker or fuse to prevent overloads.

Question 100: What is a 'header' in door or window rough opening framing?

The nailing flange of a window unit
The top plate above a window
The finishing trim board above a door or window
A horizontal structural member that spans the opening and transfers loads to the jack studs (Correct answer)

Correct answer: A horizontal structural member that spans the opening and transfers loads to the jack studs

A header is a horizontal beam placed above a door or window opening to transfer the loads from above around the opening to the jack and king studs on each side.

Question 101: _______ is a protruding element that is typically used to support a truss.

Cornice
Coping
Frieze (Correct answer)
Lintel

Correct answer: Frieze

A frieze, in architectural and construction contexts, can refer to a horizontal band or element that often serves both decorative and structural purposes. While commonly known for ornamentation, a structural frieze board can be specifically designed and used to support the lower edge of a truss or roof structure, effectively transferring the roof loads to the supporting walls below.

Question 102: What is the correct mortar type for load-bearing masonry walls?

Type M or S (Correct answer)
Type K
Type O
Type N

Correct answer: Type M or S

ASTM C270 specifies Type M or Type S mortar for load-bearing and below-grade masonry due to their higher compressive strengths.

Question 103: In cost estimating, what does 'contingency' refer to?

Profit margin added to labor costs
The cost of temporary structures
A percentage added to cover unforeseen expenses (Correct answer)
Permit and inspection fees

Correct answer: A percentage added to cover unforeseen expenses

Contingency is an amount added to a construction estimate (typically 5–15%) to account for unforeseen conditions, design changes, and uncertainties.

Question 104: _______ is the name for the foundation, which consists of a thick slab of reinforced cement covering the entire region to support highly concentrated structural loads.

Strap footing
Raft footing (Correct answer)
Combined footing
All of the options are correct

Correct answer: Raft footing

A raft footing, also known as a mat foundation, is a large, continuous slab of reinforced concrete that covers the entire footprint of a structure. This type of foundation is employed when individual footings would cover more than half the building area, or when the soil's bearing capacity is low. It effectively distributes heavy, concentrated structural loads over a much larger area, reducing the pressure exerted on the underlying soil.

Question 105: A water-logged soil's ability to support weight can be increased by:

Increasing soil density
Soil draining (Correct answer)
Grouting
Increasing the foundation's depth

Correct answer: Soil draining

Water-logged soil has significantly reduced bearing capacity because the water fills the soil pores, decreasing the effective stress between soil particles. Draining the soil removes this excess water, thereby increasing the effective stress and improving its ability to support loads. This process directly addresses the root cause of the weakened bearing capacity in saturated soils.

Question 106: What does 'AFF' stand for on construction drawings?

Adjusted Finish Framework
Architectural Finish Floor
Allowance For Framing
Above Finish Floor (Correct answer)

Correct answer: Above Finish Floor

AFF stands for 'Above Finish Floor' and is used to specify the height of fixtures, switches, outlets, and other elements measured from the finished floor surface.

Question 107: What is 'admixture' in concrete mix design?

Water added at the job site
The type of cement used
The aggregate portion of the mix
A material added to concrete to modify its properties (Correct answer)

Correct answer: A material added to concrete to modify its properties

Admixtures are materials added to concrete in small quantities to modify properties like workability, setting time, air content, or durability.

Question 108: What is the standard water-to-cement ratio range for most structural concrete mixes?

0.20–0.30
0.65–0.75
0.35–0.45
0.45–0.60 (Correct answer)

Correct answer: 0.45–0.60

Most structural concrete uses a water-to-cement (w/c) ratio of 0.45–0.60; lower ratios increase strength while higher ratios improve workability but reduce strength.

Question 109: What is the recommended minimum thickness for a residential concrete driveway slab?

3 inches
4 inches (Correct answer)
2 inches
6 inches

Correct answer: 4 inches

ACI recommends a minimum 4-inch thickness for residential concrete driveways to handle typical passenger vehicle loads without excessive cracking.

Question 110: The depth of soil exploration for large embankments and dams should not be less than _______.

h/8
h/4
1/2 h
2 h (Correct answer)

Correct answer: 2 h

For critical structures like large embankments and dams, thorough soil exploration is essential to assess stability and potential settlement. The depth of exploration must extend significantly below the base of the structure to identify all relevant soil layers and their properties. A common guideline is that the depth should not be less than 2h, where 'h' is the height of the embankment or dam, to adequately investigate the stress influence zone.

Question 111: What is 'general conditions' cost in a construction estimate?

Indirect project costs like supervision, temporary facilities, and insurance (Correct answer)
The cost of structural framing
The cost of site preparation
Direct labor costs for skilled trades

Correct answer: Indirect project costs like supervision, temporary facilities, and insurance

General conditions costs cover indirect expenses required to complete a project, including project management, temporary utilities, site trailers, and insurance.

Question 112: When examining the area, it is discovered that a large layer of very firm clay sits on top of a thick layer of soft clay. The following kind of foundation is helpful in this circumstance:

Grillage foundation
All of the options are incorrect
Pile formation
Raft foundation (Correct answer)

Correct answer: Raft foundation

In a scenario where a large layer of very firm clay sits on top of a thick layer of soft clay, a raft foundation (also known as a mat foundation) is the most suitable choice. A raft foundation is a large concrete slab that covers the entire footprint of the building, distributing the structural load over a wide area. This significantly reduces the pressure on the underlying soft clay layer and minimizes the risk of differential settlement, ensuring overall stability.

Question 113: The soil's bearing capacity cannot be increased by

Ramming dirt with crushed stone
Watering the soil's surface (Correct answer)
Making sand heaps
Removing subsurface water

Correct answer: Watering the soil's surface

Watering the soil's surface generally decreases its bearing capacity, especially for cohesive soils like clay, by increasing the moisture content and reducing shear strength. Conversely, methods such as making sand heaps (implying compaction or replacement), ramming dirt with crushed stone (compaction and reinforcement), and removing subsurface water (reducing pore pressure) are all effective techniques used to improve soil bearing capacity and stability.

Question 114: What is the function of a 'king stud' in window and door framing?

The center stud in a wall
A decorative stud at the entrance
A full-height stud on each side of an opening that runs from bottom plate to top plate (Correct answer)
The first stud installed in a wall frame

Correct answer: A full-height stud on each side of an opening that runs from bottom plate to top plate

King studs run the full height of the wall alongside an opening, supporting the trimmer studs and transferring loads from the header to the plates.

Question 115: What is the purpose of 'fire blocking' in wall assemblies per the International Residential Code?

To add structural rigidity to walls
To slow the spread of fire through concealed stud cavities and wall spaces (Correct answer)
To provide thermal insulation
To provide a nailing surface for drywall

Correct answer: To slow the spread of fire through concealed stud cavities and wall spaces

Fire blocking is required to limit the spread of fire and hot gases through concealed spaces in walls, floors, and attics by creating barriers at specified intervals.

NASCLA Accredited Examination for Commercial General Building Contractors

The NASCLA Commercial General Building Contractor exam is a nationally recognized, open-book licensing examination covering construction project planning, building codes, trade practices, OSHA safety, and contractor business law. Accepted for reciprocity in 17+ U.S. states.

115

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300 min

Time Limit

70%

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