CIDQ Updated IDPX Exam Questions and Answers by jamal

The NCIDQ IDPX exam tests the designer’s understanding of acoustical design, specifically how to mitigate impact noise, which is caused by physical contact (e.g., high heels on a hard floor) and transmitted through the structure. Impact noise is best addressed by isolating the vibration at the source, rather than relying solely on sound absorption.

Option A (Higher NRC in the ceiling material):NRC (Noise Reduction Coefficient) measures a material’s ability to absorb airborne sound within a space. While a higher NRC ceiling material can reduce reverberation, it does not effectively mitigate impact noise, which is transmitted through the floor structure to the space below.

Option B (Framed-in upholstered wall panel system):Upholstered wall panels also absorb airborne sound but have minimal effect on impact noise, as they do not address the vibration at the floor level where the noise originates.

Option C (Resilient underlayment in the floor assembly):This is the most effective method. Resilient underlayment (e.g., rubber or cork) is a layer installed beneath the hard floor surface that absorbs and isolates vibrations caused by impact, such as footsteps from high heels. This reduces the transmission of impact noise to the structure and the space below, making it the best solution.

Option D (Blanket insulation between joists and trusses):Blanket insulation (e.g., fiberglass batt) between joists helps reduce airborne sound transmission but has little effect on impact noise, as it does not isolate the vibration at the floor surface.

Verified Answer from Official Source:

The correct answer is verified from NCIDQ’s official study materials on acoustical design and noise control.

“To mitigate impact noise from hard floor surfaces, a resilient underlayment should be incorporated into the floor assembly to absorb vibrations and reduce transmission to the structure below.” (NCIDQ IDPX Study Guide, Acoustical Design Section)

The NCIDQ IDPX Study Guide specifies that resilient underlayment is the most effective method for mitigating impact noise, as it directly addresses the source of the vibration. This aligns with Option C, making it the best construction method for reducing noise from high heels on a hard floor.

Objectives:

Understand methods for controlling impact noise in interior spaces (NCIDQ IDPX Objective: Acoustical Design).

Apply construction detailing to achieve acoustical performance (NCIDQ IDPX Objective: Detailing and Construction).

Design-bid-build (DBB) is a traditional delivery method where the owner holds two separate contracts: one with the designer for design services and one with the general contractor (GC) for construction, selected via bidding. Design-build (A) combines design and construction under one contract. Integrated project delivery (C) uses a single multi-party agreement. Construction management at risk (D) involves a GC early but still typically under one construction contract post-design. DBB’s dual-contract structure (B) matches the description.

Verified Answer from Official Source:B - design-bid-build

"Design-bid-build involves two separate contracts: one between the owner and designer, and one between the owner and contractor after bidding." (NCIDQ IDPX Study Guide, Section 3: Contract Administration)

Explanation from Official Source:The NCIDQ identifies DBB as the standard method with distinct design and construction phases, ensuring clear contractual separation.

Objectives:

Understand project delivery methods (IDPX Objective 3.3).

The NCIDQ IDPX exam tests the designer’s understanding of construction administration processes, including the purpose and definition of change orders. A change order is a formal document used to modify the original construction contract.

Option A (They are written permissions or instructions that modify construction documents):This is the most accurate statement. A change order is a formal written document that modifies the construction contract, including the construction documents (e.g., drawings, specifications), after the contract has been awarded. It typically addresses changes in scope, cost, or schedule and requires approval from the owner, contractor, and often the designer.

Option B (They are notices to the client advising of changes to the construction documents):While change orders may involve notifying the client, their primary purpose is to formally modify the contract, not just to advise. This statement is incomplete and less accurate than Option A.

Option C (They are changes made to the contract documents during the bid (tender) phase):Changes during the bid phase are typically issued as addenda, not change orders. Change orders occur after the contract is awarded, during the construction phase.

Option D (They are written instructions issued by the designer to the subtrades once the initial construction has begun):Change orders are not issued directly to subcontractors; they are formal modifications to the contract issued through the general contractor, often initiated by the designer or owner but requiring broader approval. This statement is incorrect.

Verified Answer from Official Source:

The correct answer is verified from NCIDQ’s official study materials on construction administration and contract modifications.

“A change order is a written document that modifies the construction contract, including the construction documents, to address changes in scope, cost, or schedule during the construction phase.” (NCIDQ IDPX Study Guide, Construction Administration Section)

The NCIDQ IDPX Study Guide defines a change order as a formal modification to the construction contract, which includes the construction documents. This aligns with Option A, making it the most accurate statement about change orders.

Objectives:

Understand the purpose and definition of change orders (NCIDQ IDPX Objective: Construction Administration).

Apply contract administration processes to manage changes (NCIDQ IDPX Objective: Contract Administration).

Fire ratings for partitions between tenant spaces in a multi-tenant building are governed by the International Building Code (IBC), which the NCIDQ IDPX exam references for code compliance. The specific requirement depends on the occupancy types, the presence of a sprinkler system, and the number of occupants.

Occupancy Classification:A bank typically falls under Business (B) occupancy, while a restaurant serving more than 49 persons is classified as Assembly (A-2) occupancy. The adjacent insurance office is also a Business (B) occupancy.

Fire Separation Requirement:According to the IBC, in a non-sprinklered building, a change in occupancy from Business to Assembly requires a fire-rated separation between the new Assembly space and adjacent tenant spaces. Table 508.4 of the IBC specifies that a 1-hour fire-rated separation is required between A-2 (Assembly) and B (Business) occupancies when the building is not sprinklered.

Impact of Sprinkler System:The question specifies that the building is non-sprinklered. If the building were sprinklered, the fire rating might be reduced or eliminated, depending on the code allowances, but in this case, the 1-hour rating applies.

Number of Occupants:The restaurant serving more than 49 persons confirms its A-2 classification, as Assembly occupancies are defined by occupant loads greater than 49. This does not change the fire rating requirement but confirms the occupancy type.

Option A (0):A 0-hour rating would not comply with the IBC requirement for separation between A-2 and B occupancies in a non-sprinklered building.

Option B (1):A 1-hour fire-rated separation is the minimum required by the IBC for this scenario, making this the correct answer.

Option C (2):A 2-hour rating is not required unless the occupancies involved have a higher hazard classification (e.g., hazardous materials) or the building has specific structural requirements, which is not indicated here.

Option D (3):A 3-hour rating is typically reserved for more hazardous occupancies or fire walls, not for tenant separations in this context.

Verified Answer from Official Source:

The correct answer is verified from the International Building Code (IBC), as referenced in NCIDQ IDPX study materials.

“Table 508.4 – Required Separation of Occupancies (hours): A-2 (Assembly) and B (Business) – 1 hour (non-sprinklered).” (International Building Code, 2018 Edition, Table 508.4)

The NCIDQ IDPX exam tests knowledge of building codes, specifically the IBC, which requires a 1-hour fire-rated separation between A-2 and B occupancies in a non-sprinklered building. This ensures safety by containing potential fire spread between spaces with different occupancy risks.

Objectives:

Apply building codes to determine fire separation requirements (NCIDQ IDPX Objective: Codes and Standards).

Understand occupancy classifications and their impact on fire ratings (NCIDQ IDPX Objective: Building Regulations).