version: "1.0.0" name: building-codes description: > 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.

Building Codes

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

• 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

A-2: Assembly for food and/or drink consumption

• Examples: restaurants, bars, nightclubs, banquet halls, cafeterias
• Occupant load factor: 1.4 m² net per person (15 ft² net) for unconcentrated

tables/chairs; 0.65 m² net (7 ft²) for standing/concentrated use

• Typical fire load: moderate to high (40-80 MJ/m²) due to kitchen equipment
• Key code requirements: commercial kitchen hood suppression (Type I hood per

IMC 507), grease duct fire protection, separation from assembly seating

A-3: Assembly for worship, recreation, or amusement not in A-1/A-2

• Examples: churches, mosques, synagogues, museums, galleries, libraries (reading

rooms), community halls, bowling alleys, courtrooms

• 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.

F-1: Factory Industrial Moderate-Hazard

• Examples: aircraft manufacturing, furniture manufacturing, millwork, printing,

woodworking

• Occupant load factor: 11.6 m² gross per person (125 ft² gross)
• Typical fire load: high (80-200+ MJ/m²)
• Key code requirements: often requires Type I or II construction for multi-story;

sprinklers per IBC 903.2.4 when area exceeds threshold

F-2: Factory Industrial Low-Hazard

• Examples: beverage bottling, brick manufacturing, ceramic production, foundries,

glass products, metal fabrication (noncombustible)

• Occupant load factor: 11.6 m² gross per person (125 ft² gross)
• Typical fire load: low to moderate (20-60 MJ/m²)
• Key code requirements: most permissive industrial classification; noncombustible

materials in process reduce fire load

Group H -- High-Hazard

Buildings containing materials that pose a physical or health hazard beyond exempt quantities per IFC Table 307.1(1) and 307.1(2).

H-1: Detonation hazard

• Materials: explosives, organic peroxides (unclassified detonable)
• Key code requirements: detached building, minimum setback distances per

quantity-distance tables, blast-resistant construction

H-2: Deflagration or accelerated burning hazard

• Materials: flammable gases, flammable/combustible liquids (Class I-A, I-B, I-C),

organic peroxides (Class I), oxidizers (Class 4)

• Key code requirements: explosion venting, mechanical ventilation, automatic

sprinklers, max 1-story for some uses

H-3: Physical hazard materials not in H-1 or H-2

• Materials: combustible fiber, flammable solids, consumer fireworks (1.4G),

oxidizers (Class 1-3)

• Key code requirements: sprinklers, separation from other occupancies

H-4: Health hazard materials

• Materials: corrosives, highly toxic materials, toxic materials
• Key code requirements: continuous ventilation, emergency alarm,

spill containment

H-5: Semiconductor fabrication and similar

• Materials: HPM (hazardous production materials) in semiconductor fabs
• Key code requirements: HPM storage and handling per IFC Chapter 27,

continuous gas monitoring, emergency ventilation

Group I -- Institutional

Buildings where occupants are under restraint or incapable of self-preservation.

I-1: Condition 1, supervised residential (more than 16 persons)

• Examples: assisted living, group homes (> 16), halfway houses, residential

board and care

• Occupant load factor: 18.6 m² gross per person (200 ft² gross)
• Typical fire load: moderate (40-60 MJ/m²)
• Key code requirements: NFPA 13 sprinklers required, manual fire alarm,

smoke detection in sleeping rooms and corridors

I-2: Medical care / 24-hour supervision (more than 5 persons)

• Examples: hospitals, nursing homes, psychiatric facilities, detoxification
• Occupant load factor: 22.3 m² gross per person (240 ft² gross) inpatient
• Typical fire load: moderate (40-80 MJ/m²)
• Key code requirements: defend-in-place strategy, smoke compartments max

2090 m² (22,500 ft²), 2-hour fire-rated corridors in some jurisdictions, 1-hour corridor per IBC Table 1020.1, automatic sprinklers required

I-3: Restrained occupancy

• Examples: prisons, jails, reformatories, detention centers
• Occupant load factor: 11.1 m² gross per person (120 ft² gross)
• Conditions 1-5 based on degree of restraint
• Key code requirements: staff-release smoke detection, remote locking,

defend-in-place with smoke compartments

I-4: Day care (more than 5 persons of any age)

• Examples: adult day care, child care for children under 2.5 years
• Occupant load factor: 3.3 m² net per person (35 ft² net)
• Key code requirements: if above or below level of exit discharge,

classified as I-4; otherwise may be E or I-4 depending on occupants

Group M -- Mercantile

Buildings for display and sale of merchandise.

• Examples: department stores, retail shops, drug stores, markets, gas stations,

motor fuel-dispensing facilities

• Occupant load factor: 2.8 m² gross per person (30 ft² gross) for ground floor

and basement; 5.6 m² gross (60 ft²) for upper floors

• Typical fire load: moderate to high (50-150 MJ/m²) depending on stock
• Key code requirements: sprinklers when fire area > 1115 m² (12,000 ft²);

high-piled combustible storage (IFC Chapter 32) when stock > 3.7 m (12 ft)

Group R -- Residential

Buildings providing sleeping accommodations (not I group).

R-1: Transient (stays < 30 days)

• Examples: hotels, motels, boarding houses (transient)
• Occupant load factor: 18.6 m² gross per person (200 ft² gross)
• Typical fire load: moderate (30-60 MJ/m²)
• Key code requirements: automatic sprinklers (NFPA 13), single-station

smoke alarms in each sleeping room + corridor, manual fire alarm

R-2: Permanent (stays >= 30 days, more than 2 dwelling units)

• Examples: apartment buildings, condominiums, dormitories, monasteries
• 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.

S-1: Storage Moderate-Hazard

• Examples: furniture storage, tire storage, mattress storage, motor vehicle

repair garages, aircraft hangars (repair/storage)

• Occupant load factor: 27.9 m² gross per person (300 ft² gross)
• Typical fire load: high (80-200+ MJ/m²)
• Key code requirements: sprinklers when fire area > 1115 m² (12,000 ft²);

repair garages require mechanical ventilation per IMC

S-2: Storage Low-Hazard

• Examples: parking garages, aircraft hangars (storage only), noncombustible

material storage (metal, stone, glass)

• Occupant load factor: 27.9 m² gross per person (300 ft² gross)
• Typical fire load: low to moderate (10-40 MJ/m²)
• Key code requirements: open parking garages (IBC 406.5) get significant

height/area increases; enclosed garages require CO detection

Group U -- Utility and Miscellaneous

Buildings not classified in any other group.

• Examples: agricultural buildings, carports, fences > 1.8 m (6 ft), retaining

walls, tanks, towers, barns, greenhouses, sheds

• 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)
• Bearing walls (exterior): 3-hour FRR
• Bearing walls (interior): 3-hour FRR
• Floor construction: 2-hour FRR
• Roof construction: 1.5-hour FRR
• Typical materials: reinforced concrete, protected steel
• Applications: high-rise buildings, hospitals, large assembly

Type IB

• Structural frame: 2-hour FRR
• Bearing walls (exterior): 2-hour FRR
• Bearing walls (interior): 2-hour FRR
• Floor construction: 2-hour FRR
• Roof construction: 1-hour FRR
• Typical materials: reinforced concrete, protected steel
• Applications: mid-rise to high-rise office, residential, institutional

Type II -- Noncombustible (reduced ratings)

Structural elements are noncombustible but with lower or no fire resistance ratings.

Type IIA

• 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: protected steel, light-gauge steel framing with gypsum
• Applications: mid-rise office, retail, educational

Type IIB

• Structural frame: 0-hour FRR (noncombustible, unprotected)
• 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 steel, metal deck
• Applications: warehouses, single-story commercial, big-box retail

Type III -- Exterior Noncombustible, Interior Any

Exterior walls are noncombustible; interior structure may be combustible.

Type IIIA

• Structural frame: 1-hour FRR
• Bearing walls (exterior): 2-hour FRR (noncombustible)
• Bearing walls (interior): 1-hour FRR
• Floor construction: 1-hour FRR
• Roof construction: 1-hour FRR
• Typical materials: masonry/concrete exterior, wood-frame interior with

gypsum protection

• Applications: 3-5 story residential (apartments, hotels), mixed-use podium

Type IIIB

• Structural frame: 0-hour FRR
• Bearing walls (exterior): 2-hour FRR (noncombustible)
• Bearing walls (interior): 0-hour FRR
• Floor construction: 0-hour FRR
• Roof construction: 0-hour FRR
• Typical materials: masonry exterior, unprotected wood interior
• Applications: low-rise mixed-use, retail with residential above

Type IV -- Heavy Timber and Mass Timber

Type IV (Legacy Heavy Timber, now Type IV-HT)

• Structural frame: heavy timber (HT) -- min dimensions per IBC 602.4

(columns min 203 mm / 8 in, beams min 152 x 203 mm / 6 x 8 in)

• Bearing walls (exterior): 2-hour FRR (noncombustible)
• Floor construction: heavy timber (min 76 mm / 3 in thick)
• Roof construction: heavy timber (min 51 mm / 2 in thick)
• No concealed spaces permitted

Type IV-A (Mass Timber, highest protection)

• Structural frame: 3-hour FRR (mass timber fully encapsulated with

noncombustible protection)

• Floor/roof: 2-hour FRR (encapsulated)
• 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:

(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.)

Section 3: Height and Area Limitations

Calculating Allowable Height

IBC controls height two ways:

1. Allowable stories above grade plane (IBC Table 504.4)
2. Allowable building height in feet/meters (IBC Table 504.3)

Both must be satisfied. The more restrictive governs.

Sprinkler height increase (IBC 504.2):

• An NFPA 13 sprinkler system adds 6.1 m (20 ft) to allowable height
• Adds 1 story to allowable stories (except for certain H and I occupancies)
• Type IB and higher with Group B, M, or S-2: unlimited height when sprinklered

Calculating Allowable Area

Base allowable area per floor is given by IBC Table 506.2 based on occupancy and construction type.

Frontage increase (If):

If = [F/P - 0.25] × 100 / 0.75

Where:

• F = building perimeter fronting on public way or open space > 6.1 m (20 ft) wide
• P = total building perimeter
• Maximum If = 75%
• Minimum F/P = 0.25 (no increase below this)

Sprinkler increase (Is):

• Multi-story: Is = 200% (area triples) for NFPA 13 system
• Single-story: Is = 300% (area quadruples) for NFPA 13 system

Allowable area per floor (Aa):

Aa = At + [At × If / 100] + [At × Is / 100]

Where At = tabular area from Table 506.2

Allowable total building area:

Total = Aa × number of stories (up to 3 stories)

For buildings > 3 stories, total area is not limited per floor but overall building footprint is governed by Aa.

Unlimited Area Buildings (IBC 507)

A building may have unlimited area when ALL of the following are met:

1. Single story (one story above grade plane)
2. NFPA 13 sprinkler system throughout
3. Construction type and occupancy per the following:

• Type I or IIA: Groups A, B, E, F, H (limited), M, S
• Type IIIA or IV: Groups B, F, M, S (with 18.3 m / 60 ft setback all sides)
• Type IIA: Group A-4 (open air) without sprinkler requirement

1. Perimeter access: 18.3 m (60 ft) minimum setback from lot lines on all

sides, or public way frontage for fire department access

These provisions enable large-footprint buildings: convention centers, big-box retail, warehouses, aircraft hangars, manufacturing plants.

Section 4: Means of Egress

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

1. 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).

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)

1. 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)

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:

(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:

(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)

(*Corridor walls in I occupancies are often required by other sections to be smoke partitions regardless of Table 1020.1 rating.)

Section 6: Plumbing Fixtures

Minimum Plumbing Fixture Requirements (IBC Table 2902.1 / IPC Table 403.1)

Minimum number of fixtures per occupant by occupancy group:

Assembly (A):

• Water closets: 1 per 125 males / 1 per 65 females
• Lavatories: 1 per 200 persons
• Drinking fountains: 1 per 500 persons
• Service sinks: 1 per building

Business (B):

• Water closets: 1 per 25 males / 1 per 25 females (up to 50 occupants);

additional per larger counts

• Lavatories: 1 per 40 persons
• Drinking fountains: 1 per 100 persons
• Service sinks: 1 per building

Educational (E):

• Water closets: 1 per 50 males / 1 per 50 females
• Lavatories: 1 per 50 persons
• Drinking fountains: 1 per 100 persons

Mercantile (M):

• Water closets: 1 per 500 males / 1 per 750 females (per code cycle --

verify current edition)

• Customer facilities required when floor area > 929 m² (10,000 ft²)

Residential (R-1, R-2):

• 1 water closet, 1 lavatory, 1 bathtub/shower per dwelling unit or

guest room

• Drinking fountains: 0 (private units)

Industrial / Factory (F):

• Water closets: 1 per 100 males / 1 per 100 females
• Lavatories: 1 per 100 persons
• Drinking fountains: 1 per 400 persons

Institutional (I):

• Varies by condition: I-2 requires accessible patient bathing and toilet

facilities per occupant ratios defined by licensing authorities

• Typically 1 WC per patient room in hospitals

Gender-Neutral / All-User Toilet Provisions

Current code trends (2021 IBC and later amendments):

• Single-occupant toilet rooms may be designated for use by any gender
• Multi-stall all-gender restrooms addressed in some jurisdictions
• Fixture count may be combined when using all-gender single-occupant rooms

Section 7: International Code Comparison

IBC (United States)

• Scope: Model code adopted by all 50 states (with local amendments)
• Height limits: Set by construction type and occupancy per prescriptive tables
• Fire resistance: Prescriptive fire resistance ratings per construction type

(Tables 601, 602)

• Accessibility: ICC A117.1 referenced; ADA/ABA standards enforced federally
• 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

1. 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.

1. 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.

1. 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.

1. 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.

1. 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.