Comprehensive building code expertise covering IBC (International Building Code) occupancy classification, construction types I through V, height and area limitations, means of egress design, fire separation and protection requirements, plumbing fixture calculations, and international code comparison across IBC, Building Regulations (England & Wales), Eurocodes, NCC (Australia), and NBC (Canada). Provides specific code references, dimensional requirements, fire resistance ratings, and calculation methods for architectural compliance.
Amanbh99791 スター2026/04/15
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This skill provides practitioner-grade knowledge of building codes for architectural
design, focusing on the International Building Code (IBC) as the primary framework
with international comparisons. All dimensional values are given in metric with
imperial equivalents where standard practice requires.
Section 1: IBC Occupancy Groups
The IBC classifies every building or portion of a building into one of 10 occupancy
groups based on its use and the characteristics of its occupants. Correct classification
is the single most consequential code decision an architect makes -- it drives
construction type, height and area limits, egress requirements, fire separation,
and plumbing fixture counts.
Group A -- Assembly
Buildings where people gather for civic, social, or recreational purposes. The defining
characteristic is a concentration of persons who are generally unfamiliar with the
building layout, making egress critical.
A-1: Assembly with fixed seating for viewing performances
Examples: theaters, concert halls, cinemas, lecture halls with fixed seats
Occupant load factor: 0.65 m² net per person (7 ft² net) for fixed seating;
count actual seats when installed
関連 Skill
Typical fire load: moderate (30-60 MJ/m²), but high life-safety risk from
concentrated occupancy
Key code requirements: panic hardware on exit doors, illuminated exit signs,
emergency voice/alarm communication for occupant loads > 300, accessible seating
dispersed per ADA/ICC A117.1
Occupant load factor: 0.65 m² net per person (7 ft² net) for worship with
fixed pews; 1.4 m² net (15 ft²) for unconcentrated use; museums and galleries
2.8 m² net (30 ft²)
Typical fire load: variable (20-80 MJ/m²)
Key code requirements: museums with irreplaceable collections warrant
sprinkler protection regardless of threshold; libraries with stack areas
use 9.3 m² gross (100 ft²) per person
A-4: Assembly for viewing indoor sporting events
Examples: arenas, skating rinks, indoor swimming pool spectator areas
Occupant load factor: 0.65 m² net per person (7 ft² net) for fixed seating;
count seats
Typical fire load: low to moderate (20-50 MJ/m²)
Key code requirements: similar to A-1; crowd management plan for large venues;
smoke-protected assembly seating provisions (IBC 1029) allow increased travel
distance to 122 m (400 ft) when open-air or smoke-protected
A-5: Assembly for outdoor activities
Examples: outdoor stadiums, grandstands, bleachers, amusement park structures
Occupant load factor: count seats or 0.65 m² net (7 ft²) for fixed seating
Typical fire load: very low
Key code requirements: IBC 1029 smoke-protected assembly provisions typically
apply; less restrictive construction type requirements due to open-air nature
Group B -- Business
Buildings for office, professional, or service transactions.
Examples: offices, banks, outpatient clinics (fewer than 5 care recipients
incapable of self-preservation), government buildings, laboratories testing
and research (non-hazardous), post offices, radio/TV stations, educational
above 12th grade (universities)
Occupant load factor: 9.3 m² gross per person (100 ft² gross)
Typical fire load: moderate (40-80 MJ/m²), primarily paper and furnishings
Key code requirements: less restrictive than assembly; corridor rating may be
0 hr when sprinklered (Table 1020.1); max travel distance 76 m (250 ft)
sprinklered, 61 m (200 ft) unsprinklered
Group E -- Educational
Buildings used for education through the 12th grade by 6 or more students.
Examples: schools (K-12), day care for more than 5 children older than 2.5 years
Occupant load factor: 1.9 m² net per person (20 ft² net) for classrooms
Typical fire load: moderate (30-60 MJ/m²)
Key code requirements: storm shelter provisions per ICC 500 in tornado-prone
regions; fire alarm with voice/evacuation capability; classroom doors must
be lockable from inside (active-shooter provisions, IBC 1010.1.4.4)
Group F -- Factory and Industrial
Buildings for assembling, fabricating, manufacturing, or processing goods.
Occupant load factor: 18.6 m² gross per person (200 ft² gross)
Typical fire load: moderate (40-80 MJ/m²)
Key code requirements: NFPA 13 or 13R sprinklers (13R permitted for
buildings up to 4 stories per NFPA 13R scope), interconnected smoke alarms
in each unit, fire alarm when > 16 units
R-3: One- and two-family dwellings and townhouses
Examples: single-family houses, duplexes, townhouses (max 3 stories),
adult/child care for <= 5 persons, congregate living <= 16
Occupant load factor: 18.6 m² gross per person (200 ft² gross)
Typical fire load: moderate (40-80 MJ/m²)
Key code requirements: IRC (International Residential Code) may be used
instead of IBC; NFPA 13D residential sprinklers in many jurisdictions
R-4: Residential care/assisted living (5-16 persons)
Examples: small group homes, small assisted living, alcohol/drug recovery
Occupant load factor: 18.6 m² gross per person (200 ft² gross)
Key code requirements: Condition 1 (ambulatory) or Condition 2 (non-ambulatory);
Condition 2 requires conformance with I-1 or I-2 provisions
Group S -- Storage
Buildings for storage not classified as hazardous.
Occupant load factor: 27.9 m² gross per person (300 ft² gross)
Typical fire load: variable
Key code requirements: agricultural buildings exempt from many IBC provisions
per IBC 312; private garages classified U if not S-2
Section 2: Construction Types
The IBC defines 5 construction types (I through V) with two subcategories each
(A and B), for a total of 10 classifications. Additionally, the 2021 IBC introduced
Type IV subcategories for mass timber. Construction type determines fire resistance
ratings for structural elements and, combined with occupancy, sets height and area
limits.
Type I -- Noncombustible
The most fire-resistive construction. All structural elements are noncombustible.
Type IA
Structural frame: 3-hour fire resistance rating (FRR)
All mass timber surfaces covered by noncombustible protection (typically
2 layers of 16 mm Type X gypsum board)
Maximum 18 stories per IBC (2021+)
Type IV-B (Mass Timber, partial exposure)
Structural frame: 2-hour FRR
Floor/roof: 2-hour FRR
Limited exposed mass timber permitted: up to 20% of ceiling area,
40% of walls (noncombustible protection on remainder)
Maximum 12 stories per IBC (2021+)
Type IV-C (Mass Timber, exposed)
Structural frame: 2-hour FRR
Floor/roof: 2-hour FRR
Mass timber may be fully exposed (no required noncombustible covering)
Maximum 9 stories per IBC (2021+)
Fire resistance achieved by oversizing timber members beyond structural
requirements to account for charring
Type V -- Combustible
Wood-frame or other combustible construction.
Type VA
Structural frame: 1-hour FRR
Bearing walls (exterior): 1-hour FRR
Bearing walls (interior): 1-hour FRR
Floor construction: 1-hour FRR
Roof construction: 1-hour FRR
Typical materials: wood-frame with gypsum board enclosure
Applications: 3-5 story residential (with podium), townhouses,
small commercial
Type VB
Structural frame: 0-hour FRR
Bearing walls (exterior): 0-hour FRR
Bearing walls (interior): 0-hour FRR
Floor construction: 0-hour FRR
Roof construction: 0-hour FRR
Typical materials: unprotected wood-frame
Applications: 1-2 story houses, small commercial, agricultural
Height and Area by Construction Type (IBC Table 504.3/504.4 Summary)
Selected maximum heights (stories / feet) and areas (ft² per floor) for
sprinklered buildings:
Occupancy
Type IA
Type IB
Type IIA
Type IIB
Type IIIA
Type VA
Type VB
A-2
UL/UL
12/180
12/85
12/75
12/85
4/70
2/40
B
UL/UL
12/180
12/85
12/75
12/85
4/70
2/40
R-2
UL/UL
12/180
12/85
12/75
12/85
4/70
3/50
S-1
UL/UL
12/180
6/79
4/48
5/48
4/39
2/26
(UL = Unlimited. All areas shown in thousands of ft². Height in stories/feet.
Values are with sprinkler increase per IBC 504.2. Actual project values must be
verified against IBC Table 504.3, 504.4, and 506.2.)
Means of egress is the continuous and unobstructed path of travel from any occupied
point in a building to a public way. It consists of three components.
Three Components
Exit Access -- the path from any occupied point to an exit. Includes
rooms, corridors, aisles, ramps, and unenclosed stairs within exit access.
Not fire-rated (except corridor requirements per Table 1020.1).
Exit -- the fire-rated portion separating exit access from exit discharge.
Includes:
Interior exit stairways (enclosed stairs)
Interior exit ramps
Exit passageways (horizontal fire-rated corridors connecting stairs to
exit discharge)
Horizontal exits (fire wall with fire doors allowing passage to adjacent
fire compartment)
Exit Discharge -- the path from the exit to the public way. Includes
exterior exit doors, vestibules, exit courts, exterior stairs. Max 50%
of exits may discharge through the level of exit discharge (ground floor)
if sprinklered and path through ground floor is protected.
Number of Exits Required (IBC Table 1006.2.1)
Occupant Load
Minimum Exits
1-500
2
501-1,000
3
> 1,000
4
Exception for single exit: Certain occupancies with small occupant loads
and short travel distances may have a single exit per IBC Table 1006.2.1:
Group B: max 49 occupants, max travel distance 23 m (75 ft), max 1 story
Group R-2: max 4 dwelling units per floor, max travel distance 38 m (125 ft)
sprinklered
Travel Distance (IBC Table 1017.2)
Maximum travel distance from the most remote point to the nearest exit:
Occupancy
Unsprinklered
Sprinklered
A
61 m (200 ft)
76 m (250 ft)
B
61 m (200 ft)
91 m (300 ft)
E
61 m (200 ft)
76 m (250 ft)
F-1
61 m (200 ft)
76 m (250 ft)
H-1
23 m (75 ft)
23 m (75 ft)
H-2
23 m (75 ft)
30 m (100 ft)
H-3
NP
30 m (100 ft)
I-1
61 m (200 ft)
76 m (250 ft)
I-2
NP
61 m (200 ft)
M
61 m (200 ft)
76 m (250 ft)
R
61 m (200 ft)
76 m (250 ft)
S-1
61 m (200 ft)
76 m (250 ft)
S-2
91 m (300 ft)
122 m (400 ft)
U
61 m (200 ft)
76 m (250 ft)
(NP = not permitted without sprinklers)
Common Path of Egress Travel
The portion of exit access that must be traversed before two separate paths to
two exits become available:
General: 23 m (75 ft)
Groups B, F, S (sprinklered): 30 m (100 ft)
Group R (sprinklered): 38 m (125 ft)
Groups I-1, I-2: 15 m (50 ft)
Dead-End Corridors
General: 6.1 m (20 ft) maximum dead-end corridor
Sprinklered B, F-1, S-1: 15 m (50 ft)
Groups I-2, I-3: 6.1 m (20 ft), no increase
Exit Width Calculation
Stairways:
7.6 mm (0.3 in) per occupant served
Minimum stair width: 1118 mm (44 in) for occupant load >= 50;
914 mm (36 in) for < 50
Level components (doors, corridors, ramps):
5.1 mm (0.2 in) per occupant served
Minimum corridor width: 1118 mm (44 in) general; 1829 mm (72 in)
for I-2 corridors; 2438 mm (96 in) for E corridors
Example: 600 occupants, 2 stairs:
Each stair serves 300 occupants (at minimum; balanced loading)
Stair width = 300 × 7.6 mm = 2,280 mm required
Provide 2,300 mm (or two 1,150 mm stairs is insufficient -- each must
be 2,280 mm? No -- total capacity across all exits must accommodate
total occupant load, with largest single exit excluded)
IBC 1005.1: with any one exit blocked, remaining exits must handle
total load. With 2 exits, each must handle 100% of load
Revised: each stair = 600 × 7.6 mm = 4,560 mm? No -- each stair
handles 50%, but IBC requires total minus largest single exit
Correct application: 2 exits, each 50% = 300 occupants per stair
= 300 × 7.6 = 2,280 mm per stair
(Note: The convergence factor and actual calculation method should be verified
against the specific IBC edition adopted by the jurisdiction.)
European Comparison (EN/BS)
EN standard stair width: 1,100 mm minimum (BS 9999: 1,050 mm minimum
for up to 150 persons per floor)
Travel distance measured differently: actual walking distance along
shortest route vs. IBC straight-line method
Section 5: Fire Separation Requirements
Types of Fire-Rated Construction
Fire Wall (IBC 706):
Structural independence (self-supporting, remains standing if structure
on either side collapses)
Creates separate buildings for height/area calculations
Rating: 2 hr (R, B, E, M) to 4 hr (H, F-1, S-1)
Fire Barrier (IBC 707):
Continuous from floor to underside of floor/roof above (or through roof)
Used for: occupancy separation, exit enclosures, incidental use separation,
shaft enclosures, horizontal exits
Rating: per table requirements (typically 1-2 hr)
Fire Partition (IBC 708):
May terminate at underside of fire-rated floor/ceiling or roof/ceiling
assembly above
Used for: dwelling unit separation, sleeping unit separation, corridor walls
Rating: typically 1 hr (0.5 hr for corridor in some sprinklered conditions)
Smoke Barrier (IBC 709):
Continuous membrane from outside wall to outside wall or floor to floor
Used for: I-2 smoke compartments, I-3 smoke compartments
Rating: 1 hr minimum, with smoke-tight construction
Occupancy Separation (IBC Table 508.4)
When different occupancies share a building using the separated occupancy method:
Adjacent Occupancies
Separation (hr) S / NS
A, B, E, M, R, S / A, B, E, M, R, S
1 / 2
A, B, E, M, R, S / F-1, S-1
1 / 2
A, B, E, M, R, S / H-1
NP / NP
A, B, E, M, R, S / H-2
2 / 3
A, B, E, M, R, S / H-3, H-4, H-5
1 / 2
A, B, E, M, R, S / I-1, I-3, I-4
1 / 2
A, B, E, M, R, S / I-2
2 / NP
H-1 / any
NP / NP
(S = sprinklered, NS = nonsprinklered, NP = not permitted)
Shaft Enclosures (IBC 713)
Shafts connecting 4 or fewer stories: 1-hour fire barrier
Shafts connecting more than 4 stories: 2-hour fire barrier
Applies to: elevator shafts, mechanical shafts, stairways, garbage chutes,
laundry chutes, duct shafts
Corridor Fire Rating (IBC Table 1020.1)
Occupancy
Sprinklered
Nonsprinklered
H-1, H-2, H-3
1 hr
1 hr
H-4, H-5
1 hr
1 hr
I-2
0 hr*
NP
I-1, I-3
0 hr*
1 hr
A, B, E, F, M, S, U
0 hr
1 hr
R
0.5 hr
1 hr
(*Corridor walls in I occupancies are often required by other sections to be
smoke partitions regardless of Table 1020.1 rating.)
Energy: IECC (International Energy Conservation Code) or ASHRAE 90.1
Building Regulations (England & Wales)
Scope: Statutory Instruments enforced through Approved Documents A-S
Height limits: No prescriptive height/area table; fire strategy and structural
design govern feasibility. Approved Document B provides guidance by "purpose group"
(equivalent to occupancy)
Fire resistance: Approved Document B, Volume 1 (dwellings) and Volume 2
(other buildings). Fire resistance periods: 30 min (up to 5 m height), 60 min
(up to 18 m), 90 min (up to 30 m), 120 min (over 30 m). Post-Grenfell:
combustible material ban above 18 m (Building Safety Act 2022)
Accessibility: Approved Document M (Volume 1: dwellings, Volume 2: other
buildings). Category M4(2) accessible and adaptable dwellings; M4(3) wheelchair
user dwellings
Energy: Approved Document L; Part L 2021 uplift targets ~31% CO2 reduction
over 2013 standards; Future Homes Standard 2025 targeting 75-80% reduction
Eurocodes + National Annexes
Scope: Structural design standards (EN 1990-1999) adopted across EU/EEA
with nationally determined parameters (NDPs)
Height limits: Not addressed by Eurocodes; governed by national building
regulations (e.g., Germany: Landesbauordnung, France: Code de la Construction)
Fire resistance: EN 1991-1-2 (fire actions), EN 1992-1-2 through
EN 1996-1-2 (material-specific fire design). Parametric fire curves as
alternative to standard fire
Accessibility: EN 17210 (accessibility and usability of the built
environment) published 2021; implementation varies by member state
Energy: EPBD (Energy Performance of Buildings Directive); nearly zero-energy
building (nZEB) requirements since 2021 for all new buildings
NCC (National Construction Code, Australia)
Scope: Building Code of Australia (BCA) forms Volume 1 and 2 of NCC
Height limits: Determined by building classification (Class 1-10) and
type of construction (A, B, C corresponding roughly to IBC Types I, III, V).
Rise in storeys and floor area per Table C1.1
Fire resistance: NCC Volume 1 Specification C1.1; fire resistance levels (FRL)
expressed as structural adequacy / integrity / insulation in minutes
(e.g., 120/120/120)
Accessibility: NCC Section D (Access and Egress) + AS 1428.1 (Design for
Access and Mobility, General Requirements)
Energy: NCC Section J (Energy Efficiency); NatHERS for residential
NBC (National Building Code, Canada)
Scope: Model code published by NRC; adopted by provinces with modifications
Height limits: Part 3 Table 3.2.2.A (building area and height based on
major occupancy and construction type: noncombustible vs combustible)
Fire resistance: Part 3 Subsection 3.2.2; fire-resistance ratings by
building use and height. Combustible construction limited to 6 storeys
(recent amendments allow up to 12 for mass timber in some provinces)
Accessibility: CSA B651 (Accessible Design for the Built Environment);
NBC Part 3 Section 3.8 (Barrier-Free Design)
Energy: NECB (National Energy Code for Buildings) 2020; tiered energy
performance targets
Key Comparative Observations
Prescriptive vs performance: IBC and NBC use prescriptive tables for
height/area. UK and Australian codes allow performance-based fire engineering
as a standard path, enabling designs exceeding prescriptive limits with
adequate justification.
Fire resistance philosophy: IBC rates individual assemblies. UK and
Eurocodes focus on whole-building fire strategy with insulation, integrity,
and load-bearing criteria assessed separately.
Accessibility scope: ADA focuses on public accommodations and commercial
facilities. UK Part M applies to all new buildings including dwellings.
Australia AS 1428.1 is among the most stringent for public buildings.
Energy trajectory: All jurisdictions are converging toward near-zero
energy new construction by 2030. UK's Future Homes Standard (2025) and EU's
EPBD recast (2024) lead with most aggressive targets.
Mass timber: IBC 2021 introduced Type IV-A/B/C for tall mass timber.
NBC allows up to 12 stories in some provinces. UK has no prescriptive tall
timber path but performance-based approaches have enabled projects up to
10 stories. Australia NCC 2019 introduced provisions for mass timber up to
25 m effective height.
This skill provides general code guidance for architectural decision-making.
All code interpretations must be verified against the specific edition adopted
by the authority having jurisdiction (AHJ). Building officials have final
authority on code compliance.