Engineer Interior Architecture cheat sheet

Net assignable area excludes circulation, walls, columns, and mechanical shafts; gross area includes all of these plus exterior wall thickness measured to the outside face.

Efficiency ratio = net assignable area ÷ gross area; typical office values fall between 0.75 and 0.85, and lower values signal heavy core or circulation load.

Minimum clear circulation widths: 36 in (915 mm) for a single-occupant path, 44 in (1120 mm) for two-way accessible traffic, 60 in (1525 mm) where a wheelchair must turn around.

The accessible turning circle is 60 in (1525 mm) diameter; a T-shaped turning space fits within a 36 in (915 mm) square with 36 in arms.

Reach ranges for accessible storage and controls: 15–48 in (380–1220 mm) above finished floor for forward reach, 9–54 in (230–1370 mm) for side reach.

Daylight factor = interior illuminance at the work plane ÷ unobstructed exterior horizontal illuminance, expressed as a percentage under overcast sky.

Bubble diagramming precedes blocking: adjacency matrices rank required proximity, then block plans test area allocations against the net-to-gross budget.

Universal design principles: equitable use, flexibility, simple intuitive use, perceptible information, tolerance for error, low physical effort, size and space for approach and use.

Occupant load = floor area ÷ occupant load factor; common factors: 150 gross for business, 100 gross for assembly unconcentrated, 15 net for assembly concentrated, 50 gross for mercantile street floor.

Egress capacity = occupant load × unit width factor; level components use 0.2 in (5 mm) per occupant, stairways 0.3 in (7.6 mm), ramps 0.3 in, and the minimum clear width is 36 in (915 mm).

Occupancy classification drives height and area limits; mixed occupancies are handled by the accessory, nonseparated, or separated occupancy method.

Type I and II construction require noncombustible materials; Type III allows combustible interior elements; Type IV heavy timber and Type V allow combustible structural framing.

Allowable area increases come from frontage (up to 75 percent for full open frontage) and automatic sprinkler protection (up to 200 percent for multi-story buildings).

Means of egress components in order: exit access, exit, and exit discharge; each has separate travel-distance and enclosure requirements.

Accessible route clear width is 36 in (915 mm) minimum with passing spaces of 60 × 60 in at intervals not exceeding 200 ft.

A change in level greater than 1/4 in (6 mm) requires a ramp; ramps need a maximum slope of 1:12, landings at top and bottom, and handrails on both sides where required.

Travel distance limits are measured along the path of egress travel to the nearest exit; business occupancies commonly allow 200–300 ft depending on sprinkler protection.

Dead-end corridors are limited to 20 ft in most nonsprinklered occupancies and 50 ft where sprinklered, per the applicable code edition.

Common path of egress travel limits are shorter than total travel distance and apply where occupants must pass a single point before reaching two distinct routes.

Two exits are required when occupant load exceeds the threshold for the occupancy, commonly 49 for business and 49–99 for assembly depending on sprinkler status.

Exit remoteness: exits must be separated by at least one-half the diagonal of the area served, or by a fire-rated separation where the code permits.

Exit signs require visible marking, illumination, and directional indicators; internally illuminated signs are tested for visibility and must be connected to emergency power.

Fire-resistance ratings of assemblies are stated in hours and tested per ASTM E119 or UL 263; opening protectives carry their own rating (e.g., 20-, 45-, 60-, 90-minute).

Smoke barriers require 1-hour fire-resistance with protected openings; smoke partitions are not the same as smoke barriers and have lesser requirements.

Sprinkler trade-offs often reduce required ratings and travel distances but never eliminate the requirement for exit signage or an accessible means of egress.

Class A interior finish has flame spread 0–25; Class B is 26–75; Class C is 76–200; smoke-developed index is limited to 450 for most interior finish applications.

Flooring flammability is tested by the critical radiant flux method (ASTM E648); Class I is the highest and required in corridors of certain occupancies.

Wet-area flooring slip resistance is expressed as a coefficient of friction; 0.60 or higher is commonly specified for level surfaces, higher for ramps.

Specification divisions follow MasterFormat: Division 09 covers finishes, Division 08 openings, Division 10 specialties, Division 12 furnishings.

Specification methods: closed (proprietary) specifies one product; open specifies performance criteria; basis-of-design names a product that sets the standard.

Substitution requests are typically submitted within a stated period after contract award; the architect's decision is usually final and not a basis for delay claims.

VOC content limits for interior paints and coatings are set by regulation and by green building rating systems; low-VOC does not automatically mean zero emissions.

Carpet and resilient flooring require a moisture test of the substrate before installation; excessive slab moisture causes adhesive failure and delamination.

Steel beam deflection limits: L/360 for floors under live load, L/240 for total load, and L/180 for cantilevers, unless a stricter criterion is specified.

Concrete slab thickness and reinforcement govern point-load capacity; rooftop or heavy equipment loads on an existing slab require structural verification.

Non-load-bearing partitions can be removed without structural review; any partition supporting structure or resisting lateral loads cannot.

Light-gauge steel studs: 3-5/8 in (92 mm) studs at 16 in on center support typical gypsum board partitions; 6 in studs are used for taller walls.

Gypsum board fire-rated assemblies are listed by UL design number; substitutions of board type or fastener spacing can void the rating.

Suspended ceiling grid requires a minimum 2 in (51 mm) clearance above the ceiling for access and sprinkler head placement; seismic bracing is required in high-seismic zones.

Anchor types: expansion anchors for cracked concrete require listed cracked-concrete anchors; adhesive anchors must be installed per the manufacturer's temperature and cure limits.

Structural drawings and architectural drawings must be coordinated for beam depths, column locations, and slab openings before interior framing begins.

Illuminance is measured in footcandles (lumens per square foot); 1 fc = 10.76 lux. Office work planes are commonly designed at 30–50 fc.

Power density = total connected lighting load ÷ floor area, expressed in W/sq ft or W/m²; energy codes set maximum values by space type.

Luminous efficacy is lumens per watt; LED sources typically exceed 100 lm/W, well above incandescent at roughly 15 lm/W.

Color rendering index (CRI) ranges to 100; values of 80 or higher are typical for office and retail, 90+ for color-critical tasks.

Sound transmission class (STC) rates airborne sound isolation of a partition; impact insulation class (IIC) rates floor-ceiling impact noise.

Noise reduction coefficient (NRC) rates absorption from 0 (reflective) to 1.0 (fully absorptive); it is measured in a reverberation room.

Reverberation time (RT60) is the time for sound to decay 60 dB; speech privacy in open offices improves with absorptive ceilings and sound masking.

HVAC ductwork and VAV boxes must be coordinated with ceiling height; minimum duct clearance and access panels affect the reflected ceiling plan.

ASHRAE Standard 55 governs thermal comfort; Standard 62.1 governs ventilation rates, commonly 5 cfm per person plus a per-area component.

LEED credit categories: Integrative Process, Location and Transportation, Sustainable Sites, Water Efficiency, Energy and Atmosphere, Materials and Resources, Indoor Environmental Quality, Innovation, Regional Priority.

Recycled content and regional materials credits are calculated by cost of materials; documentation requires manufacturer declarations and cost data.

Environmental Product Declarations (EPDs) disclose life-cycle impacts; Health Product Declarations (HPDs) disclose ingredient and hazard information.

Low-emitting materials credits cover adhesives, sealants, paints, coatings, flooring, and composite wood; formaldehyde limits are a common compliance point.

Indoor air quality management during construction includes protection of ducts, filtration during construction, and a flush-out or air testing before occupancy.

Daylight and views credits require a percentage of regularly occupied floor area to meet illuminance and view thresholds, not just window presence.

Carbon accounting distinguishes embodied carbon (materials and construction) from operational carbon (energy use over the building's life).

Construction and demolition waste diversion is measured by weight or volume; a diversion rate target is set and tracked with hauler documentation.

Cost per square foot = total project cost ÷ gross floor area; compare only projects with similar scope, location, and date.

Escalation is applied to historical cost data using an index ratio: current index ÷ historical index, applied to the historical cost.

Contingency is a percentage added to the estimate for unknowns; design contingency is larger early and shrinks as design progresses.

A change order modifies scope, price, or time and requires signature authority; a construction change directive orders work before agreement on price.

Request for information (RFI) documents a question and the binding answer; submittals transmit product data, samples, or shop drawings for review.

Schedule float is the amount of time an activity can slip without delaying the project; critical path activities have zero float.

Pay applications are certified by the architect based on observed progress; retainage is withheld per contract and released at substantial completion or later.

Substantial completion starts warranty periods and is documented by a certificate; punch lists record incomplete or defective work.

Standard of care is the degree of skill and care ordinarily exercised by similarly situated professionals under similar circumstances; it is not perfection.

Architects' obligations: competence, confidentiality, avoidance of conflicts of interest, honest representation of qualifications, and fair dealing with contractors.

Agency relationships: the architect is typically the owner's agent for administration but not a guarantor of the contractor's performance.

Ownership of instruments of service remains with the architect unless assigned; licenses grant use for the project, not resale or reuse.

Professional liability insurance covers errors and omissions; it differs from general liability, which covers bodily injury and property damage.

Coordination duties include reviewing shop drawings for design intent, not for dimensional accuracy or means and methods, which remain the contractor's responsibility.

Seal and signature requirements vary by jurisdiction; stamping drawings outside one's competence or unlicensed practice is an ethics violation.

Records retention and document delivery: maintain project records for the statutory period, and respond to requests for information promptly and in writing.