13.1 Building Codes (IBC/IRC), Permits & Inspection Sequence

Model Building Codes in Nevada & Regional Amendments

The PSI Class B trade exam is open book and lets you bring the 2018 International Building Code, ACI 318-11 or 318-14, and ACI 530/530.1-11 or -13, so learn where things are in the 2018 IBC. (Local jurisdictions may have adopted newer editions, but exam code questions follow the edition listed in the bulletin.) Commercial and residential construction across Nevada is governed by model building codes promulgated by the International Code Council (ICC), specifically the International Building Code (IBC) for commercial, multi-family, and institutional structures, and the International Residential Code (IRC) for detached one- and two-family dwellings and townhouses not more than three stories in height. Under Nevada law, authority to adopt and enforce building codes is delegated to local municipal and county building departments. Rather than enforcing a single monolithic state code without variation, Nevada's primary population centers adopt the ICC model codes with rigorous, region-specific amendments.

Regional Amendment Coalitions

• Southern Nevada Building Officials (SNBO): A regional consensus committee comprising the building officials of Clark County, the City of Las Vegas, the City of Henderson, the City of North Las Vegas, and Boulder City. The SNBO publishes regional amendments to address unique local hazards, including extreme desert thermal swings, aggressive caliche rock and expansive clay formations, intense flash-flood potential, high solar radiation, and the unique fire-life safety demands of high-rise resort casino hospitality properties.
• Northern Nevada Regional Amendments: Adopted cooperatively across Washoe County, the City of Reno, and the City of Sparks. Northern Nevada amendments heavily focus on substantial Sierra Nevada foothill snow loads, freezing winter ground depths, high-elevation wind forces, and active seismic faulting along the Walker Lane tectonic zone.

                         Nevada Model Code Regulatory Structure

             ┌────────────────────────────────────────────────────────┐
             │           ICC Model Building Codes (IBC / IRC)         │
             └───────────────────────────┬────────────────────────────┘
                                         │
               ┌─────────────────────────┴─────────────────────────┐
               ▼                                                   ▼
     Southern Nevada (SNBO)                              Northern Nevada
  (Clark County, Las Vegas,                            (Washoe County, Reno,
    Henderson, North Las Vegas)                              Sparks)
               │                                                   │
    ┌──────────┴──────────┐                             ┌──────────┴──────────┐
    ▼                     ▼                             ▼                     ▼
• Caliche & Swelling   • High-Rise Resort            • Heavy Sierra        • High-Altitude
  Soil Foundations       Casinos (Group A/R-1)         Snow Loads            Wind / Seismic
• Flash-Flood Controls • NFPA Sprinkler Rules        • Deep Frost Lines      Design Rules

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IBC Chapter 3 Building Occupancy Classifications

A building's Occupancy Classification reflects the nature of its intended human activity, the associated fire hazard, and the physical vulnerability of its occupants. Under IBC Chapter 3, every structure or portion of a structure must be classified into one or more of ten primary occupancy groups. When a building houses multiple uses, it is regulated either as non-separated occupancies (where the most restrictive provisions apply throughout) or as separated occupancies (where fire barriers isolate differing occupancies).

Exam Key Point: Small assembly spaces containing fewer than 50 persons are legally classified as part of the primary occupancy they serve (typically Group B), or as Group B if independent. Additionally, a room or space used for assembly purposes that is less than 750 square feet in area and accessory to another occupancy is classified as Group B.

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IBC Chapter 6 Types of Construction

IBC Chapter 6 categorizes all buildings into five distinct Types of Construction (Types I, II, III, IV, and V), based on the combustibility of materials and their fire-resistance ratings. Each type (except Type IV) is bifurcated into Subtype A and Subtype B:

• Subtype A (Protected): Structural framing elements, exterior bearing walls, floors, and roofs possess a mandatory minimum fire-resistance rating (typically 1-hour or 2-hour protection achieved via spray-applied fireproofing, gypsum encasement, or concrete cover).
• Subtype B (Unprotected): Structural framing members require 0-hour fire-resistance ratings, meaning bare structural steel, bare wood studs, or unrated assemblies may be utilized.

                                IBC Construction Type Spectrum
  Least Combustible / Highest Fire Rating                    Most Combustible / Lowest Fire Rating
  ◄──────────────────────────────────────────────────────────────────────────────────────────────►
    TYPE I                 TYPE II                TYPE III               TYPE IV          TYPE V
  Fire-Resistive         Noncombustible          Ordinary             Heavy Timber      Wood Frame
   (I-A & I-B)            (II-A & II-B)        (III-A & III-B)          (IV-HT)        (V-A & V-B)
  Concrete & Steel       Steel & Masonry      Masonry Walls /         Mass Timber /     Any Material
  Protected Frame        Commercial Frames    Wood Interior           Solid Glulam      Allowed by Code

Construction Type Summaries

1. Type I (Fire-Resistive Noncombustible): Structural frame, exterior walls, and interior floors/roofs are constructed entirely of noncombustible materials (structural steel encased in fireproofing, cast-in-place post-tensioned concrete, or precast concrete). Type I-A requires 3-hour fire-resistance for exterior bearing walls and structural frames; Type I-B requires 2-hour ratings. Mandatory for high-rise commercial structures and resort hotel towers exceeding height thresholds.
2. Type II (Noncombustible): Similar to Type I in that all exterior walls, bearing frames, floors, and roofs must be noncombustible (bare structural steel, light-gauge steel framing, masonry, metal decking), but with lower fire-resistance requirements. Type II-A requires 1-hour protection throughout; Type II-B allows 0-hour unprotected steel framing. Widely utilized in commercial retail strip centers and modern office parks.
3. Type III (Ordinary Construction): Exterior walls must be constructed entirely of noncombustible materials (reinforced concrete tilt-up panels, brick masonry, or concrete masonry units [CMU]), while interior walls, columns, beams, floor decks, and roof framing are permitted to be any material permitted by code, including wood framing. Type III-A provides 1-hour protected interior framing; Type III-B allows unprotected combustible interior framing.
4. Type IV (Heavy Timber / Mass Timber): Exterior walls are noncombustible (or fire-retardant-treated wood), while interior structural elements are massive, solid, or laminated wood timbers without concealed spaces. Minimum dimensions for heavy timber columns are nominally $8 \times 8$ inches (supporting floor loads) or $6 \times 8$ inches (supporting roof loads), and floor beams must be at least $6 \times 10$ inches. Modern revisions recognize Subtypes IV-A, IV-B, and IV-C for mass timber (cross-laminated timber [CLT]).
5. Type V (Any Materials Permitted / Wood Frame): Structural elements, exterior walls, and interior framing may be constructed of any materials permitted by code—most commonly standard light-frame dimensional lumber ($2 \times 4$, $2 \times 6$) or cold-formed steel studs. Type V-A requires 1-hour fire-resistance protection on all structural framing; Type V-B is unprotected (0-hour rating), typical of single-family residences and low-density wood-frame structures.

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Building Height & Allowable Area Calculations (IBC Chapter 5)

Under IBC Chapter 5, the maximum allowable height (in feet and stories) and the maximum allowable floor area per story ($A_a$) for a proposed building are determined by cross-referencing its Occupancy Classification against its Type of Construction using tabular base values (IBC Tables 504.3, 504.4, and 506.2). To maximize building envelopes without triggering more expensive construction types, contractors and designers utilize statutory area increases.

The Allowable Area Equation (IBC 2018)

Since the 2015 edition, Table 506.2 lists separate tabular areas for nonsprinklered buildings (NS), one-story sprinklered buildings (S1) and multistory sprinklered buildings (SM). The sprinkler increase is built into the table. For a single-occupancy building, IBC 2018 Equation 5-1 is:

$A_a = A_t + \left( NS \times I_f \right)$

• $A_t$ = tabular allowable area from Table 506.2 for the building's sprinkler status (NS, S1 or SM).
• $NS$ = the nonsprinklered tabular value for the same occupancy and construction type.
• $I_f$ = frontage increase factor (Section 506.3).

(Older codes, such as the 2012 IBC, used $A_a = A_t + (A_t \times I_f) + (A_t \times I_s)$ with a separate sprinkler factor $I_s$. Do not use that method with the 2018 IBC.)

1. Frontage Area Increase ($I_f$) Formula

When a building has more than 25 percent (0.25) of its exterior perimeter fronting on a public way or open space having a minimum clear width ($W$) of 20 feet, the base tabular area may be increased based on open perimeter access for fire apparatus:

$I_f = \left[ \frac{F}{P} - 0.25 \right] \times \frac{W}{30}$

• $F$ = Length of building perimeter fronting on a public way or open space having a clear width $\ge 20$ feet.
• $P$ = Total exterior perimeter of the building (linear feet).
• $W$ = Width of the public way or open space (feet). The value of $W$ cannot exceed 30 feet in the calculation ($20 \le W \le 30$). If the open space width exceeds 30 feet, $W$ is capped at 30, meaning the multiplier $W/30$ equals 1.0.
• If $F/P \le 0.25$, the building is not eligible for a frontage increase ($I_f = 0$).

2. Sprinkler Columns in Table 506.2

Where a building is sprinklered throughout with an NFPA 13 system (Section 903.3.1.1):

• One-story buildings: use the S1 value, which is 4 times the NS value.
• Multistory buildings: use the SM value, which is 3 times the NS value.
• NFPA 13R and 13D systems: do not qualify for the sprinkler area values; use the NS value for area. A 13R system can still qualify for the height increase in Section 504.

                    Worked Engineering Example: Allowable Area Calculation

  Building Parameters:
  • Occupancy: Group B (Business)
  • Construction Type: Type II-B (Unprotected Noncombustible)
  • Nonsprinklered Tabular Area (NS): 23,000 sq ft (IBC 2018 Table 506.2)
  • Stories: 2 Stories (Multi-story building)
  • Total Perimeter (P): 600 linear feet
  • Frontage on Public Way ≥ 20' (F): 450 linear feet
  • Open Space Width (W): 35 feet (capped at maximum 30 feet in formula)
  • Fire Protection: Fully protected with an approved NFPA 13 automatic sprinkler system

  Step 1: Calculate Frontage Increase Factor (If):
          If = [ (F / P) - 0.25 ] × (W / 30)
          If = [ (450 / 600) - 0.25 ] × (30 / 30)
          If = [ 0.75 - 0.25 ] × 1.0 = 0.50 (50% increase)

  Step 2: Select the tabular area (At) from Table 506.2:
          Multistory, NFPA 13 sprinklered: use SM = 3 x NS = 69,000 sq ft

  Step 3: Calculate Allowable Area per Story (Aa), IBC 2018 Eq. 5-1:
          Aa = At + (NS x If)
          Aa = 69,000 + (23,000 x 0.50)
          Aa = 69,000 + 11,500 = 80,500 sq ft per story

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IBC Chapter 10 Means of Egress Architecture

A Means of Egress is an unobstructed and continuous path of vertical and horizontal egress travel from any occupied point in a building or structure to a public way. IBC Chapter 10 divides every means of egress into three continuous, distinct components:

                              Three Means of Egress Components

   [ Occupied Space ]
          │
          ▼
   ┌────────────────┐      That portion of egress travel leading to an exit (aisles, hallways,
   │ 1. EXIT ACCESS │ ──► interior corridors, tenant doors). Subject to common path of travel
   └──────┬─────────┘      and maximum travel distance limits.
          │
          ▼
   ┌────────────────┐      That portion of egress system separated by fire-resistance-rated
   │    2. EXIT     │ ──► construction from other building spaces (interior fire-rated stairways,
   └──────┬─────────┘      exit passageways, horizontal exits, exterior exit doors at grade).
          │
          ▼
   ┌────────────────┐      That portion of egress travel between the termination of an exit and
   │ 3. EXIT        │ ──► a public way (exterior exit courts, grade-level exit discharge yards,
   │    DISCHARGE   │      alleys, or dedicated public sidewalks).
   └──────┬─────────┘
          │
          ▼
   [ Public Way (Street / Highway) ]

Occupant Load Calculations (IBC Section 1004)

The Occupant Load is the total number of persons for whom the means of egress of a building or portion thereof must be engineered. It is calculated by dividing the designated floor area by the floor area allowance per occupant specified in IBC Table 1004.5:

$\text{Occupant Load} = \frac{\text{Floor Area (sq ft)}}{\text{Floor Area Allowance per Occupant (sq ft / person)}}$

• Gross Floor Area: The floor area within the inside perimeter of the exterior walls, without deducting corridors, stairways, closets, or partition thicknesses. Used for business, industrial, mercantile, and residential occupancies.
• Net Floor Area: The actual occupied area, excluding accessory spaces such as corridors, stairways, toilet rooms, and mechanical closets. Used for assembly and educational spaces.

Door Dimensions, Clearances & Mandatory Swing Rules (IBC Section 1010)

• Minimum Clear Door Width: Egress door openings must provide a minimum clear width of 32 inches (813 mm), measured between the face of the door and the stop, with the door open to 90 degrees. For a standard swinging door, this requires a nominal door slab width of at least 36 inches (3'-0").
• Maximum Door Leaf Width: The maximum width of a swinging egress door leaf is 48 inches (4'-0") nominal.
• Minimum Clear Height: Egress doors must have a minimum clear height of 80 inches (6'-8").
• Door Swing Direction (The 50-Person Rule): Egress doors must swing in the direction of egress travel when serving an occupant load of fifty (50) or more persons, or when serving any room classified as Group H (High Hazard) regardless of occupant load. Doors serving spaces with fewer than 50 persons may swing inward (against the path of egress), provided they do not swing into a required public corridor or create an egress pinch-point.
• Panic Hardware: Required on egress doors serving Group A or Group E occupancies having an occupant load of 50 or more persons, and on high hazard Group H spaces. Panic hardware unlatches the door with a maximum operating force of 15 pounds applied in the direction of exit travel.

Corridors, Travel Distance & Dead-End Limitations

• Minimum Corridor Widths (IBC Table 1020.2):
  • 44 inches: Standard minimum width for corridors serving an occupant load $\ge 50$ persons.
  • 36 inches: Corridors serving an occupant load $<50$ persons, or within a private residential dwelling unit.
  • 72 inches: Corridors in Group E (educational) facilities serving $>100$ persons, and ambulatory surgical centers.
  • 96 inches (8'-0"): Corridors in Group I-2 (hospitals and nursing homes) where bed patients are transported.
• Common Path of Travel (IBC 2018 Table 1006.2.1): The portion of exit access travel before two separate paths to two exits are available. For Groups B, F and S it is generally 75 feet without sprinklers (100 feet in Group B when the occupant load is 30 or fewer) and 100 feet with sprinklers. Group R-2 is allowed 125 feet with sprinklers.
• Maximum Travel Distance to an Exit: The maximum physical distance an occupant must walk from the most remote point within a room to the entrance of an exit. For Group B offices: 200 feet (non-sprinklered), extended to 300 feet (NFPA 13 sprinklered).
• Dead-End Corridors (IBC Section 1020.4): Where more than one exit or exit access doorway is required, dead-end corridors must not exceed 20 feet in length. Exception: In buildings of Groups B, E, F, I-1, M, R-1, R-2, S, and U equipped throughout with an approved NFPA 13 automatic fire sprinkler system, the maximum allowable length of a dead-end corridor is increased to 50 feet.

Accessible Egress & ADA Standards (ICC A117.1)

Every required accessible means of egress must comply with ICC A117.1 and the Americans with Disabilities Act (ADA) accessibility guidelines:

• Continuous Accessible Route: Must provide a minimum clear path of 36 inches, with passing spaces of $60 \times 60$ inches at intervals not exceeding 200 feet.
• Door Clearances & Operating Force: Interior hinged doors require a maximum opening force of 5 pounds (5 lbf). Door thresholds cannot exceed 1/2 inch in height (1/4 inch vertical, plus 1/4 inch beveled at a maximum 1:2 slope).
• Areas of Refuge: Where an exit stairway serves as an accessible means of egress, it generally needs an area of refuge with a $30 \times 48$ inch wheelchair space outside the required egress width, and two-way communication. Under the IBC 2018 Section 1009.3 exceptions, areas of refuge are not required at exit stairways in buildings sprinklered throughout under NFPA 13 or 13R.

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Building Permit Acquisition & Construction Plan Review

Under Nevada administrative statutes (NRS 624 and local municipal building ordinances), no general contractor may erect, enlarge, alter, repair, move, demolish, or change the occupancy of a building without first obtaining a valid Building Permit from the local building official.

Plan Review Process

1. Application & Document Submission: Submission of complete construction documents prepared, stamped, and wet- or electronically signed by a Nevada-licensed Architect and Nevada-licensed Professional Engineers (Civil, Structural, Mechanical, Electrical). Submittals include architectural floor plans, elevations, wall sections, structural calculations, geotechnical soil investigation reports, mechanical energy calculations (COMcheck / REScheck), electrical fault current and panel schedules, and civil grading plans.
2. Multi-Agency Plan Check Routing: The building department routes drawings through specialized review divisions: Building/Structural, Mechanical, Electrical, Plumbing, Fire Prevention Bureau, Civil/Traffic Engineering, Environmental Health (Southern Nevada Health District or Washoe County Health District for commercial kitchens and pools), and Planning/Zoning.
3. Plan Correction Notices (Redlines): The department issues plan review correction comments. The design team generates revised drawings, clouds changes with delta revision tags, and provides written narrative responses.
4. Deferred Submittals: Certain specialized engineering packages are formally deferred during initial permit issuance, including pre-engineered manufactured wood roof trusses, structural steel shop connections, post-tensioned cable shop drawings, exterior curtain wall assemblies, and automatic fire sprinkler hydraulic calculations. Deferred submittals must be reviewed by the Architect/Engineer of Record and submitted to the building official for formal approval prior to fabrication or installation.

Permit Lifespan & Expiration Rules (IBC Section 105.5)

• The 180-Day Rule: Every permit issued by the building official becomes null and void if the authorized work is not commenced within 180 days from the date of permit issuance, or if the authorized work is suspended or abandoned for a continuous period of 180 days at any time after work has commenced.
• Extensions: A contractor holding an unexpired permit may apply for a written extension, provided they demonstrate justifiable cause beyond their control. Extensions are typically granted for periods not exceeding 180 days by the building official.

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Mandatory Municipal Inspection Sequence

Construction inspections follow a rigid, sequential, and legally irreversible progression. Contractors must call for inspections at specified project milestones before the work is concealed, embedded, or covered. Proceeding to the next construction phase without obtaining an inspector's signature ("green tag") on the jobsite inspection record card constitutes an unlawful violation resulting in stop-work orders and mandatory destructive uncovering.

                      Statutory Municipal Inspection Sequence

  1. Footing & Foundation Inspection
     (Excavation clean, depth verified, rebar tied on chairs, setbacks checked BEFORE concrete pour)
          │
          ▼
  2. Concrete Slab & Underfloor Inspection
     (Underground plumbing DWV & water lines tested, vapor retarder (6-mil code minimum), rebar/mesh)
          │
          ▼
  3. Lowest Floor Elevation Certification
     (FEMA Elevation Certificate verified in Special Flood Hazard Areas BEFORE vertical framing)
          │
          ▼
  4. Rough MEP Systems Inspections
     (Plumbing DWV water head/air test, rough electrical raceways/boxes, HVAC duct pressure testing)
          │
          ▼
  5. Rough Framing Inspection
     (Conducted strictly AFTER rough MEP is signed off; checks headers, shear walls, ties, fireblocking)
          │
          ▼
  6. Insulation Inspection
     (R-values verified, draft-stopping, air sealing, baffles in soffits checked BEFORE drywalling)
          │
          ▼
  7. Drywall Fastening / Lath Inspection
     (Screw spacing, Type X gypsum board on fire walls, corner beads checked BEFORE taping/mudding)
          │
          ▼
  8. Final Inspection & Certificate of Occupancy (CO)
     (Life safety, egress hardware, MEP trim, final grading, clearances approved for occupancy)

1. Footing and Foundation Inspection

• Conducted after footing trenches are excavated to design bearing strata, forms are rigidly erected, and reinforcing steel (rebar) is tied in place, but prior to any concrete placement.
• Inspectors verify footing width and depth, clearance between steel and soil (minimum 3-inch clearance using concrete dobies), rebar overlap splices, foundation anchor bolts/hold-down hardware, and zoning property line setbacks.

2. Concrete Slab and Underfloor Inspection

• Conducted after underfloor rough plumbing, electrical conduits, and hydronic heating pipes are installed, a vapor retarder is placed with lapped seams (the IBC and IRC minimum is 6-mil polyethylene lapped at least 6 inches; many specifications require 10- or 15-mil sheets with sealed seams), and slab reinforcing (rebar or welded wire reinforcement) is positioned on chairs, but prior to pouring the concrete slab.
• Plumbing drain, waste, and vent (DWV) piping must be subjected to a hydrostatic test (filled with water to the top of the stack, minimum 10-foot head of water) or a pneumatic air test (5 psi air pressure) to verify leak-free integrity.

3. Lowest Floor Elevation Certification

• For buildings located in FEMA-designated Special Flood Hazard Areas (SFHA), a certified FEMA Elevation Certificate signed by a licensed land surveyor must be submitted and approved verifying the lowest finished floor elevation prior to vertical structural framing above the slab.

4. Rough MEP (Mechanical, Electrical, Plumbing) Inspections

• Plumbing Rough: Inspection of water supply, gas supply lines (pressure-tested with a calibrated gauge at 1.5 times working pressure, min 3 psi for 10 minutes or local standard), and DWV piping inside wall and floor cavities.
• Electrical Rough: All conduit, metallic and non-metallic sheathed cables (Romex, MC cable), raceways, panel backboxes, and junction boxes installed before drywall closure.
• Mechanical Rough: All HVAC ductwork, ventilation fans, fire dampers, gas appliance exhaust flues, and refrigerant lines installed, supported, and pressure tested.

5. Rough Framing Inspection

• Conducted strictly AFTER rough MEP trades have received official sign-off, but before insulation or interior wall coverings are applied.
• Inspectors examine load-bearing studs, headers, joists, engineered roof trusses, shear wall nailing patterns, hold-down anchors, seismic straps, uplift hurricane clips, and fireblocking/draftstopping installed at floor levels and interstitial ceiling cavities.

6. Insulation Inspection

• Conducted after rough framing and MEP sign-offs, verifying specified thermal resistance (R-values) for exterior wall cavity batt/spray foam, ceiling insulation baffles maintaining roof ventilation, and continuous air-barrier sealing around window/door perimeters and mechanical penetrations.

7. Drywall Fastening & Lath Inspection

• Conducted after gypsum board is hung on walls and ceilings, but before joints are taped and finished with joint compound.
• Inspectors verify gypsum board type (such as 5/8-inch Type X fire-rated board), thickness, and fastener spacing (screws spaced typically 8 to 12 inches on center depending on assembly fire rating).

8. Final Inspection & Occupancy Certification

• The culminating multi-trade inspection verifying building readiness: operating electrical trim and GFCI/AFCI receptacles, plumbing fixture traps and anti-scald mixing valves, HVAC commissioning, egress path clearances, illuminated exit signs, emergency battery lights, panic hardware functionality, smoke/CO alarms, and exterior site grading drainage.

Certificate of Occupancy (CO) vs. Temporary Certificate of Occupancy (TCO)

• Certificate of Occupancy (CO): The official legal document issued by the building official confirming that the completed building complies with all applicable codes, approved plans, and municipal ordinances. A structure cannot be legally occupied or put into commercial operation until the CO is granted.
• Temporary Certificate of Occupancy (TCO): Issued at the discretion of the building official when a discrete portion of a building or a specific floor is entirely code-compliant, life-safe, and functionally independent, even though minor non-critical work (such as seasonal exterior landscaping, upper-floor tenant improvements, or punch-list finishes) remains incomplete. TCOs are issued for a defined, limited period (typically 30 to 90 days), after which they must be renewed or converted to a permanent CO.