NCIDQ IDIX common mistakes
NCIDQ IDIX · Understand the traps and how to avoid them.
Treating the program as a fixed room list copied from the client's brief and moving straight to bubble diagrams, without reconciling stated areas against the actual net assignable area derived from gross floor area and circulation/mechanical/structural losses.
Candidates under time pressure accept the client's square-footage wish list at face value; they do not run the gross-to-net calculation, so the scheme is over-programmed and the later space plan cannot be made to fit, forcing rushed compromises.
What to do instead
Before any blocking, build a program table: space, quantity, net area per space, total net, then apply a realistic efficiency ratio (typically 60–75% net-to-gross for offices) and compare to available gross area. Flag the delta explicitly and document the trade-off you chose (reduce areas, stack functions, or note the shortfall).
Interviewing only the facility manager or project sponsor and never validating requirements with the people who actually use the space, then presenting a program as if it were confirmed.
Sponsors are easier to schedule and appear authoritative, so candidates skip end-user interviews and observation; the resulting program misses workflow adjacencies, storage, and equipment needs that surface only in the design review.
What to do instead
Use a structured method: separate interviews with each user group, a written questionnaire for headcounts and equipment, and at least one walk-through of existing space to observe real behaviour. Record each requirement with its source and confirm the final program in writing with the sponsor.
Building the adjacency diagram from departmental labels rather than from actual interaction frequency, so spaces that exchange people or documents hourly are placed far apart while low-traffic spaces occupy prime circulation-adjacent positions.
Org charts suggest groupings that do not match daily work; candidates also default to putting the largest department nearest the entry because it 'feels' important, ignoring the adjacency matrix they were given or should have built.
What to do instead
Construct a weighted adjacency matrix (required/desired/undesired, with a frequency or importance score) from interview data, then block the plan to maximize high-weight adjacencies while respecting code egress and structural constraints. Test the result against the matrix and be ready to explain any deliberately broken adjacency.
Ignoring the base building's structural grid, column locations, core, and lease-demised boundaries when laying out partitions, producing a plan that puts a corridor through a column line or a door where the slab edge or shear wall sits.
Candidates work on a clean schematic without overlaying the architectural base plan; under exam time pressure they treat the shell as infinitely flexible and only notice conflicts at the construction-document stage.
What to do instead
Always underlay the structural grid, columns, core, and demising lines before drawing any partition. Set a planning module that matches the column spacing, and verify that every wall and door clears structure. State the module you used in your rationale.
Choosing an HVAC delivery system by habit (e.g., defaulting to VAV with overhead diffusers everywhere) without checking ceiling plenum depth, floor-to-floor height, and whether the chosen system can actually be ducted within the available interstitial space.
Candidates memorize system types in isolation and do not connect them to the section; the plan looks fine in two dimensions, but the duct main and VAV boxes do not fit above the ceiling, or the plenum is used for return air and cannot also carry ducts.
What to do instead
For each candidate system, check the required ceiling void against available floor-to-floor minus structural depth minus finished ceiling height. Note whether the plenum is a return-air plenum (which restricts combustible materials and duct penetration). Document the system choice with its space, weight, and maintenance-access implications.
Applying occupant-load and egress calculations to the net room area instead of the gross area served, and using a single egress width for a space with multiple exits without checking the required egress capacity per exit and the remoteness of the two means of egress.
Candidates remember occupancy factors but apply them to the wrong area basis, and they forget that the required number of exits, exit access travel distance, and the separation between exits are separate checks from total width.
What to do instead
Compute occupant load from the gross floor area of each occupancy or the fixed seating count, per the applicable code. Then check, in order: number of exits, egress width per exit (capacity), travel distance, common path, and separation between exits. Show each step so an arithmetic slip is visible.
Specifying finishes and furniture by appearance and budget alone, without matching the product to the fire-resistance, flame-spread, and wet-area requirements of the space, or checking that the specified item is actually available in the required size and lead time.
Candidates treat FF&E and finishes as a styling exercise; they do not cross-check the specification against the code-required interior finish class for corridors and exit access, and they ignore lead times and substitution risk in the schedule.
What to do instead
For every finish, record the code-required interior finish class for that space and confirm the product's test data meets it. For furniture, verify dimensions against the plan, note lead time and installation sequence, and write a substitution clause. Build a finish schedule with room, product, and compliance note.
Laying out lighting by even spacing of fixtures on the ceiling grid without calculating illuminance or checking the interaction with daylight, task locations, and the reflectance of the specified finishes.
Candidates rely on rules of thumb (e.g., one fixture per X square feet) and do not connect fixture selection to the visual task, the ceiling height, or the daylight aperture; the result meets neither the task nor the energy code.
What to do instead
Start from the illuminance target for the specific task and the room's surface reflectances, then select fixtures and spacing to meet it, checking uniformity and glare. Coordinate with daylighting (aperture orientation and control) and with the ceiling layout. Note the lighting power density against the energy code allowance.
Treating acoustics as a single 'soundproofing' decision, specifying one absorptive product everywhere, rather than separating the problem into background noise, room acoustics, and sound isolation between spaces and addressing each with the right measure.
Candidates conflate absorption with isolation; adding absorptive panels to a wall does not stop speech transmission through it, and a high-NRC ceiling does not fix HVAC noise if the duct path and diffuser selection are the source.
What to do instead
Diagnose the problem type first. For room acoustics, use absorption and diffusion with a target reverberation time. For isolation, use mass, decoupling, and sealing at penetrations. For background noise, address mechanical equipment, duct lining, and diffuser velocity. Coordinate the measures with the ceiling and partition details.
Managing the project by reacting to the latest email rather than maintaining a schedule and a documented decision log, so that owner approvals, long-lead FF&E orders, and submittal review cycles are not tracked against the contract dates.
Candidates confuse activity with progress; without a baseline schedule and a decision log, they cannot show which party caused a delay, and they miss the contractual notice periods for changes and time extensions.
What to do instead
Maintain a baseline schedule with milestones, a decision/approval log with dates and owners, and a submittal register tied to the specification sections. For any change, document the request, the cost and time impact, and the notice given within the contract period. Use these records in progress meetings and in any claim discussion.