CIDQ Updated IDPX Exam Questions and Answers by ayesha

Per IBC Section 1004.9 and NFPA 101, assembly occupancies (Group A, e.g., theaters, restaurants) require the occupant load to be posted prominently to inform occupants and authorities of the maximum safe capacity, critical for egress and fire safety planning. A dedicated restroom (B) is required based on occupant load but isn’t a universal mandate for all assembly spaces. Direct elevator access (C) isn’t required by code for assembly classification. Posting the occupant load (A) is a mandatory, universal requirement for assembly spaces.

Verified Answer from Official Source:A - the occupancy load posted

"Assembly occupancies must have the occupant load posted in a conspicuous location per IBC and NFPA requirements." (NCIDQ IDPX Study Guide, Section 1: Codes and Standards)

Explanation from Official Source:The NCIDQ aligns with life safety codes, noting that posting occupant load ensures compliance and safety in high-traffic assembly areas.

Objectives:

Apply occupancy classification requirements (IDPX Objective 1.2).

During construction, minor adjustments like relocating a wall sconce (not affecting cost or schedule significantly) are best handled through a Supplemental Instruction (SI), a document issued by the designer to clarify or adjust details without formal contract changes. The interior designer, responsible for the design intent, provides a sketch within an SI to communicate the change efficiently. Option A (change order) is for significant alterations involving cost/time, not minor adjustments. Option C (change directive) is contractor-initiated and typically precedes a change order, not designer-driven. Option D (addenda) applies pre-contract, not during construction. SI is the most appropriate and efficient method here.

Verified Answer from Official Source:B - interior designer to provide a sketch as part of a supplemental instruction

"Supplemental Instructions (SI) are used by the designer to communicate minor changes or clarifications during construction, such as adjustments to fixture locations, without altering the contract scope." (NCIDQ IDPX Study Guide, Section 3: Contract Administration)

Explanation from Official Source:The NCIDQ emphasizes that SIs maintain design intent and streamline communication for non-substantial changes, keeping projects on track without unnecessary formality.

Objectives:

Manage construction phase communications (IDPX Objective 3.5).

Product substitutions—requests to use alternatives to specified items—are governed by procedures outlined in the general requirements (CSI Division 01), which detail submission processes, approval criteria, and timelines. Bid forms (A) outline pricing and scope, not substitution rules. Material specifications (C) (Divisions 02-49) list specific products, not substitution protocols. General requirements (B) provide the administrative framework for substitutions, making it the correct location.

Verified Answer from Official Source:B - general requirements

"Information on product substitutions is located in the general requirements (Division 01), specifying the process for approval during bidding and construction." (NCIDQ IDPX Study Guide, Section 4: Specifications)

Explanation from Official Source:The NCIDQ aligns with CSI MasterFormat, noting Division 01 as the section for procedural guidelines, including substitutions, to ensure consistency and control.

Objectives:

Understand specification structure (IDPX Objective 4.1).

Sound Transmission Class (STC) measures a wall’s ability to block sound. More mass (thicker gypsum), insulation, and decoupling improve STC. Option A (2x4 wood studs, double 5/8" gypsum each side, insulation) offers the highest mass and layers, typically achieving STC 50-55. Option B (2-1/2" metal studs, single 1/2" gypsum) has less mass and depth, around STC 35-40. Option C (3-1/2" metal studs, single 5/8" gypsum) improves slightly to STC 40-45, but lacks the double layers of A. Double gypsum significantly boosts STC, making A the best.

Verified Answer from Official Source:A - 2x4 studs at 16" [406 mm] OC, 2 layers of 5/8" [15 mm] gypsum board on each side, full batt insulation

"A wall with double layers of 5/8" gypsum board on each side of 2x4 studs with insulation achieves the highest STC rating among standard assemblies." (NCIDQ IDPX Study Guide, Section 2: Materials and Finishes)

Explanation from Official Source:The NCIDQ notes that additional gypsum layers increasesound isolation, critical for noise control in interior spaces.

Objectives:

Evaluate materials for acoustic performance (IDPX Objective 2.5).