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Ontario Building Code FAQ

222 plain-English answers to real Ontario Building Code questions — focused deep on Part 3 (fire protection, occupant safety and accessibility) and Part 9 (housing and small buildings).

Part 3 — Fire Protection, Occupant Safety and Accessibility

3.1Application
Which buildings fall under Part 3 of the Ontario Building Code? How is major occupancy classified under the Ontario Building Code? How are building height and building area determined under the Ontario Building Code? What is a high building under the Ontario Building Code? What are the requirements for mixed occupancy buildings in Ontario?
3.2Functional Statements / Building Fire Safety
When is noncombustible construction required under the Ontario Building Code? When are automatic sprinklers required in a building in Ontario? What are the fire department access route requirements under the Ontario Building Code? When is a fire alarm system required in a building in Ontario? How does spatial separation limit windows near property lines in Ontario? When is a standpipe system required under the Ontario Building Code?
3.3Safety Within Floor Areas
What fire separation is required between suites in Ontario? What is the minimum corridor width under the Ontario Building Code? How long can a dead-end corridor be under the Ontario Building Code? How do you calculate occupant load under the Ontario Building Code? When must doors swing in the direction of exit travel in Ontario? When does a room or suite need two egress doorways under the Ontario Building Code? How is travel distance measured within a floor area in Ontario? What fire separations are required for hazardous rooms under the Ontario Building Code? What are the aisle requirements for assembly seating in Ontario? What are the special egress rules for care occupancies under the Ontario Building Code? What are the egress requirements for residential suites under the Ontario Building Code?
3.4Exits
When are two exits required from a floor area in Ontario? How is required exit width calculated under the Ontario Building Code? How many exits does a floor area need under the Ontario Building Code? How far apart must exits be located under the Ontario Building Code? What is the maximum travel distance to an exit under the Ontario Building Code? What are the required dimensions for exit stairs under the Ontario Building Code? What are the exit sign requirements under the Ontario Building Code? What fire separation is required around exits in Ontario? What is a horizontal exit and when can it be used in Ontario? When can exterior stairs be used as exits under the Ontario Building Code? Can an exit pass through a lobby under the Ontario Building Code?
3.5Vertical Transportation
What are the elevator requirements under the Ontario Building Code? Which buildings need an elevator under the Ontario Building Code? When is a firefighters' elevator required in Ontario, and what must it include? What are the escalator and moving walk requirements in the Ontario Building Code? What does the Ontario Building Code require for elevator machine rooms? What are the code requirements for dumbwaiters and material lifts in Ontario?
3.6Service Facilities
What fire separation is required for service rooms in Ontario? Where can fuel-fired appliances be located in a Part 3 building in Ontario? What does the Ontario Building Code require for electrical vaults and transformer rooms? What are the requirements for vertical service spaces and shafts in Ontario? What are the incinerator room requirements in the Ontario Building Code?
3.7Health Requirements
How many washroom fixtures does a building need under the Ontario Building Code? When is a universal washroom required in an Ontario building? Are drinking fountains required by the Ontario Building Code? What are the medical gas piping requirements in the Ontario Building Code? What does the Ontario Building Code require for food premises like restaurant kitchens? Can a bedroom or sleeping room have no window under the Ontario Building Code?
3.8Barrier-Free Design
When does a building need to be barrier-free (accessible) in Ontario? Which buildings are exempt from barrier-free design requirements in Ontario? How wide must a barrier-free path of travel be in Ontario? How many barrier-free entrances does a building need in Ontario? What are the accessible (barrier-free) toilet stall dimensions in Ontario? What must a universal washroom include under the Ontario Building Code? What is the maximum ramp slope for barrier-free ramps in Ontario? What are the accessible parking requirements for buildings in Ontario? Where are power door operators required in Ontario buildings? How many wheelchair spaces are required in assembly seating in Ontario? How many barrier-free suites are required in hotels and apartment buildings in Ontario?
3.9Portable Classrooms
When do the Ontario Building Code portable classroom rules apply? What are the exit requirements for portable classrooms in Ontario? Do portable classrooms need a fire alarm system in Ontario? What foundations and anchorage do portable classrooms need in Ontario?
3.10Self-Service Storage Buildings
What Ontario Building Code rules apply to self-service storage buildings? What fire separations are required in a self-storage building in Ontario? How many exits does a self-storage building need in Ontario, and what are the travel distance limits? Do self-storage buildings need sprinklers under the Ontario Building Code?
3.11Public Pools
What counts as a public pool under the Ontario Building Code? What are the deck requirements for a public pool in Ontario? Where do water depth markings have to go on a public pool in Ontario? What are the drain and suction entrapment safety rules for public pools in Ontario? What emergency and safety equipment must a public pool have in Ontario? Does an outdoor public pool need a fence or enclosure in Ontario?
3.12Public Spas
What counts as a public spa or hot tub under the Ontario Building Code? What safety features does a public spa need under the Ontario Building Code? What are the water treatment and recirculation requirements for public spas in Ontario? What emergency provisions must a public spa have in Ontario?
3.13Rapid Transit Stations
When does OBC Section 3.13 apply to rapid transit stations in Ontario? What are the egress requirements for transit station platforms in Ontario? What fire safety systems are required in rapid transit stations in Ontario? Do rapid transit stations in Ontario have to be accessible?
3.14Tents and Air-Supported Structures
When does a tent need a building permit in Ontario? What flame resistance standard must tent fabric meet in Ontario? What clearance and exit requirements apply to tents in Ontario? How is the occupant limit for an event tent determined in Ontario?
3.15Signs
When does a sign need a building permit under the Ontario Building Code? What are the structural requirements for signs under the Ontario Building Code? What rules apply to projecting signs over sidewalks in Ontario? What are the requirements for roof signs on buildings in Ontario?
3.16Shelf and Rack Storage Systems
When does warehouse racking need a building permit or engineering in Ontario? Do storage racks in Ontario need to be designed for earthquakes? How does high rack storage affect sprinkler requirements in Ontario? What egress requirements apply around storage racks in warehouses in Ontario?
3.17Demountable Stages and Support Structures
When does the Ontario Building Code apply to demountable event stages? What engineering is required for demountable stages and support structures in Ontario? Are guards required on the edges of temporary stages in Ontario? What inspections are required for demountable stages in Ontario?
3.18Additional Requirements for Existing Buildings
What triggers the additional Part 3 requirements for existing buildings in Ontario? What compliance alternatives exist for existing buildings under the Ontario Building Code? How does Section 3.18 relate to Part 11 renovation rules in Ontario? What upgrades are required when changing the use of an existing building in Ontario?

Part 9 — Housing and Small Buildings

9.1General
Which buildings fall under Part 9 of the Ontario Building Code? When does a building need Part 3 design instead of Part 9 in Ontario?
9.2Definitions
What counts as a storey and building height under Part 9 in Ontario? What does 'grade' mean in the Ontario Building Code?
9.3Materials, Systems and Equipment
What concrete strength is required for house foundations in Ontario? Does framing lumber need to be grade stamped in Ontario?
9.4Structural Requirements
When can you use Part 9 span tables instead of an engineer in Ontario? What design loads apply to houses under Part 9 in Ontario? What are the basic foundation design rules for houses in Ontario?
9.5Design of Areas, Spaces and Doorways
What is the minimum bedroom size in Ontario? What is the minimum ceiling height in Ontario? What are the minimum living room, dining room and kitchen sizes in Ontario? What is the minimum door width between rooms in an Ontario house? What is the minimum hallway width in an Ontario house?
9.6Glass
Where is safety glass required in a house in Ontario? Is there a maximum glass size or thickness rule for houses in Ontario?
9.7Windows, Doors and Skylights
What standard must new windows meet in Ontario (NAFS)? How much window area is required for natural light in Ontario rooms? What are the requirements for exterior doors on houses in Ontario?
9.8Stairs, Ramps, Handrails and Guards
What is the maximum stair rise and minimum run in Ontario? What height must a stair handrail be in Ontario? How high must a deck guard or railing be in Ontario?
9.9Means of Egress
What size does a bedroom egress window need to be in Ontario? When does a house need two exits in Ontario? What are the egress requirements for basements in Ontario? What are the travel distance limits to an exit in small buildings in Ontario?
9.10Fire Protection
What fire separation does a basement apartment need in Ontario? Where are smoke alarms required in a house in Ontario? When are carbon monoxide alarms required in Ontario homes? What separation is required between an attached garage and the house in Ontario?
9.11Sound Transmission
What STC rating is required between dwelling units in Ontario? How do you build a wall or floor that meets STC 50 in Ontario?
9.12Excavation
How deep must you excavate below frost for foundations in Ontario? What are the topsoil removal and backfill rules for building in Ontario?
9.13Dampproofing, Waterproofing and Soil Gas Control
When is waterproofing required instead of dampproofing for a foundation in Ontario? What are the radon and soil gas control requirements for new houses in Ontario? Does foundation dampproofing go on the inside or outside of the wall in Ontario?
9.14Drainage
What are the weeping tile requirements for house foundations in Ontario? Where must foundation drains and weeping tile discharge in Ontario? What are the surface grading requirements around a house in Ontario?
9.15Footings and Foundations
What is the minimum footing size for a house in Ontario? How thick does a foundation wall need to be in Ontario? How deep do foundations have to be for frost protection in Ontario?
9.16Floors-on-Ground
What is the minimum concrete thickness for a basement floor slab in Ontario? What has to go under a basement floor slab in Ontario?
9.17Columns
What are the requirements for steel and wood columns in a basement in Ontario? What size footing does a basement column need in Ontario?
9.18Crawl Spaces
What are the ventilation and access requirements for crawl spaces in Ontario? What is the difference between a heated and unheated crawl space under the Ontario Building Code?
9.19Roof Spaces
How much attic ventilation does a roof need in Ontario? What are the attic access hatch requirements in Ontario?
9.20Masonry and ICF Walls Not In Contact with the Ground
How must brick veneer be supported and tied to a house in Ontario? How thick do above-grade masonry walls have to be in Ontario? What are the Ontario Building Code rules for above-grade ICF walls in houses?
9.21Masonry and Concrete Chimneys and Flues
How high does a chimney have to extend above the roof in Ontario? What are the flue lining requirements for masonry chimneys in Ontario? What clearance does a masonry chimney need from combustible materials in Ontario?
9.22Fireplaces
How big does a fireplace hearth extension need to be in Ontario? What clearances and damper requirements apply to fireplaces in Ontario?
9.23Wood Frame Construction
What stud size and spacing does the Ontario Building Code require for walls? What are the notching and drilling limits for floor joists in Ontario? What are the wall bracing and sheathing requirements for houses in Ontario?
9.24Sheet Steel Stud Wall Framing
When are steel studs allowed in a house under the Ontario Building Code? Can steel studs be used for load-bearing walls in Ontario houses?
9.25Heat Transfer, Air Leakage and Condensation Control
What are the insulation installation requirements in the Ontario Building Code? What are the attic insulation rules for houses in Ontario? Does polyethylene have to go on the warm side of the wall in Ontario?
9.26Roofing
What is the minimum roof slope for asphalt shingles and other roofing materials in Ontario? Where is ice and water shield (eave protection) required on roofs in Ontario? What are the roof flashing requirements for valleys, walls and chimneys in Ontario?
9.27Cladding
Do I need a rainscreen or air gap behind siding in Ontario? How far above the ground does siding have to be in Ontario? What are the code rules for installing vinyl siding in Ontario?
9.28Stucco
What are the lath and mix requirements for exterior stucco in Ontario? How much clearance does stucco need above the ground in Ontario?
9.29Interior Wall and Ceiling Finishes
What thickness of drywall is required and how must it be fastened in Ontario? What water-resistant backing and finish is required around tubs and showers in Ontario?
9.30Flooring
How thick does the subfloor need to be in an Ontario house? What kind of finish flooring is required in bathrooms and laundry rooms in Ontario?
9.31Plumbing Facilities
What plumbing fixtures must every dwelling unit have in Ontario? Which fixtures need hot and cold running water in an Ontario home? Is a floor drain required in the basement of a house in Ontario?
9.32Ventilation
How is the principal ventilation fan sized by number of bedrooms in Ontario? What are the exhaust fan requirements for bathrooms and kitchens in Ontario? What are the minimum openable window areas for natural ventilation in Ontario?
9.33Heating and Air-Conditioning
What indoor temperatures must a home heating system be designed to maintain in Ontario? How must heating and cooling systems be sized for houses in Ontario? What are the requirements for heating and air-conditioning ducts in Ontario homes?
9.34Electrical Facilities
Which rooms in a house require lighting outlets in Ontario? How does the Ontario Building Code relate to the Ontario Electrical Safety Code for house wiring?
9.35Garages and Carports
What are the foundation and floor slab requirements for garages in Ontario? What gas-proofing is required between an attached garage and the house in Ontario? What is the difference between a carport and a garage under the Ontario Building Code?
9.37Cottages
Which building code relaxations apply to seasonal cottages in Ontario? What foundation options are allowed for cottages in Ontario?
9.38Log Construction
What are the code requirements for log walls in Ontario? How much settling allowance do log homes need above windows, doors and partitions in Ontario?
9.39Park Model Trailers
When does the Ontario Building Code apply to park model trailers? What foundation and anchorage requirements apply to park model trailers in Ontario?
9.40Reinforced Concrete Slabs
When do the reinforced concrete slab rules apply, such as garage slabs over basements, in Ontario? What reinforcement and concrete requirements apply to suspended slabs in Ontario houses?
9.41Additional Requirements for Change of Use
What triggers change-of-use requirements in a small building in Ontario? What does the code require when converting a house to an office or daycare in Ontario? What upgrades are required when adding a second unit or basement apartment in Ontario?

More OBC topics — Parts 4 to 8

Part 4Structural Design
What loads must a guard (railing) resist under the Ontario Building Code? How is the design snow load calculated in Ontario? What live loads must residential floors be designed for in Ontario?
Part 5Environmental Separation
Where is a vapour barrier required in Ontario? What are the air barrier requirements in the Ontario Building Code? What performance standards do windows have to meet in Ontario?
Part 6Heating, Ventilating and Air-Conditioning
What are the ventilation requirements for buildings in Ontario? Where can exhaust ducts and vents discharge in Ontario? Is an HRV required in new homes in Ontario?
Part 7Plumbing
Is a backwater valve required in Ontario? Does every plumbing fixture need a trap in Ontario? What is the maximum hot water temperature allowed in Ontario?
Part 8Sewage Systems
When does Part 8 (septic systems) of the Ontario Building Code apply? How far must a septic system be from a well or house in Ontario? How is a septic tank sized in Ontario?

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