Parts 4 to 7 provisions referenced by Part 9 (Small Buildings)

Last updated October 22, 2026

Values this chapter turns on

guard point load, general locations: 1.0 kN; guard point load, general locations
guard load outward at top, general locations: 0.75 kN/m; guard load outward at top, general locations
handrail point load, any direction: 0.9 kN; handrail point load, any direction
general shower valve outlet temperature limit: 49°C; general shower valve outlet temperature limit

Part 9 often sends you out to Parts 4 to 7: for engineered guards and firewalls, for foundations beyond the Part 9 tables, for environmental separation design, and for a few HVAC and plumbing items. The Small Buildings syllabus lists only selected articles from these Parts. This chapter walks through each one. Several of these articles name external standards (CSA, ASTM). The exam can ask which standard the Code calls up, but you do not need the content of the standard.

Loads on guards, handrails and firewalls

OBC Div. B 4.1.2.1. lists the load types a structure must be designed for, each with a symbol: D (dead), E (earthquake), H (lateral earth pressure), L (live), S (snow and rain), T (temperature, shrinkage and similar effects) and W (wind). Loads are grouped as permanent, variable or rare. Buildings also get an Importance Category (Low, Normal, High or Post-disaster) for snow, wind and earthquake loads. Community centres and elementary, middle and secondary schools are High (Table 4.1.2.1.).

Table 4.1.5.3. gives minimum uniform live loads by use. A few to recognise: offices on upper floors 2.4 kPa, retail and wholesale 4.8 kPa, exits and corridors (general) 4.8 kPa, residential areas 1.9 kPa, roofs 1.0 kPa, factories 6.0 kPa.

Guard and handrail loads are in OBC Div. B 4.1.5.14.:

Element	Minimum specified live load
Guard, general locations, outward at top	0.75 kN/m or 1.0 kN point, whichever governs
Guard, open viewing stands without fixed seats, and means of egress in grandstands, stadia, bleachers and arenas	3.0 kN/m
Guard, equipment platform access ways	1.0 kN point
Guard, inward	half the outward load
Guard infill elements (pickets, panels)	0.5 kN over 100 mm by 100 mm
Guard, vertical at top	1.5 kN/m
Handrails, all	0.9 kN point, any direction
Handrails outside dwelling units	also 0.7 kN/m

Firewalls must resist the larger of the normal lateral design loads or a factored lateral load of 0.5 kPa under fire conditions. Where the structure has a lower fire-resistance rating than the firewall, assume support from one side only, or provide another support system (OBC Div. B 4.1.5.17.).

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Foundations and structural material standards

Section 4.2. applies to excavations and foundations. The syllabus excludes steel piles, high strength tendons, permafrost, swelling soils, expanding rock, construction on fill and deep foundations.

A subsurface investigation, including groundwater, must be done by or under a professional engineer (OBC Div. B 4.2.2.1.).
Field review is continuous for deep foundations, retaining structures and engineered fill, and "as required" for shallow foundations and excavation work (4.2.2.3.).
If soil, rock or groundwater differ from the design assumptions, the designer must reassess the design (4.2.2.4.).
The bearing surface must be below the level of frost damage unless the foundation is designed against frost or sits on material not susceptible to frost (4.2.4.4.).
Excavations must not damage adjacent buildings, water must be controlled, and loss of ground prevented (4.2.5.2., 4.2.5.6.).
Wood exposed to soil or air above the lowest groundwater table must be preservative treated (4.2.3.2.).

Section 4.3. names the design standard for each material: wood to CSA O86, masonry to CSA S304, concrete to CSA A23.3, structural steel to CSA S16, cold-formed steel to CSA S136, aluminum to CSA S157 (OBC Div. B 4.3.1.1., 4.3.3.1., 4.3.4.1.).

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Environmental separation

Part 5 covers heat, air, moisture and sound transfer through assemblies that separate different environments (OBC Div. B 5.1.1.1.). The syllabus excludes 5.4. (air leakage), 5.7. (surface and ground water) and 5.8. (sound).

Common threads:

Above ground climatic loads come from Supplementary Standard SB-1 (5.2.1.1.).
Materials that resist heat transfer must limit condensation on the warm side and within the assembly, and minimize ice damming on sloped roofs (5.3.1.2.).
A vapour barrier must provide the principal resistance to vapour diffusion, unless uncontrolled diffusion will not harm health, safety, use or building services (5.5.1.1.).
Assemblies exposed to precipitation must limit its entry into the assembly and prevent it reaching the interior (5.6.1.1.). Downspouts not connected to a sewer must direct water away and prevent erosion (5.6.2.2.).
Metal-framed glazing between conditioned and unconditioned space needs a thermal break, except storm units and fire-rated units (5.9.2.4.).

Notice the repeated three-part test: a requirement can be relaxed where the failure would not adversely affect the health or safety of building users, the intended use, or the operation of building services.

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HVAC installation standards and air openings

Only Sentence 6.2.1.5.(1) is listed: solid fuel-burning appliances for central heating must be installed to CSA B365 and the manufacturer's instructions (OBC Div. B 6.2.1.5.).

OBC Div. B 6.3.2.9. covers air openings. Supply, return and exhaust openings less than 2 m above the floor need grilles that stop a 15 mm sphere. Outdoor air intakes must be at least 0.3 m above roofs or grade, allowing for snow, and screens on intakes and exhaust outlets have openings of not more than 15 mm.

From OBC Div. B 6.3.2.10., the listed item is Sentence (7): a dryer exhaust duct must be independent of other exhaust ducts, cleanable over its whole length, and made of smooth corrosion-resistant material.

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Plumbing: storm drainage, temperature control, relief valves and water efficiency

Storm drainage must connect to a public storm sewer, a public combined sewer or a designated storm water disposal location (OBC Div. B 7.1.2.2.).
Hot water to tubs, showers and basins used by residents of Group B, Division 2 or 3 occupancies, group homes and child care facilities needs controls, accessible only to staff, that keep the water at not more than 43°C (7.2.10.7A.).
Shower valves must be pressure-balanced or thermostatic, with outlet temperature limited to 49°C (7.2.10.7B.).
Roof hydraulic load is the 15 min rainfall from SB-1 times the drained area plus half the largest adjoining vertical wall (7.4.10.4.). Flow control roof drains need at least one drain per 900 m² and a drain-down time of not more than 24 h.
Pressure relief valves limit tank pressure to the lesser of 1,100 kPa or half the test pressure. Temperature relief valves sense within the top 150 mm and keep water below 99°C. No shut-off valve between a tank and its relief valves (7.6.1.7.).
Public washroom lavatories need automatic shut-off (7.6.4.1.).

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Common traps

Using 0.9 kN for guards. That is the handrail point load; the guard point load is 1.0 kN.
Forgetting that the inward guard load is only half the outward one.
Using 43°C for showers in general. 43°C applies to care and child care settings; 49°C is the general shower valve limit.
Adding the full vertical wall area in roof drainage. Only half of the largest adjoining wall counts.

Chapter review

Chapter at a glance

One line per section: the idea to carry into the exam. Then the answers that most often catch candidates out.

Chapter at a glance: the key idea in each section
Section	Key idea
Loads on guards, handrails and firewalls	Firewalls must resist the larger of the normal lateral design loads or a factored lateral load of 0.5 kPa under fire conditions.
Foundations and structural material standards	Section 4.2. applies to excavations and foundations.
Environmental separation	Part 5 covers heat, air, moisture and sound transfer through assemblies that separate different environments.
HVAC installation standards and air openings	Only Sentence 6.2.1.5.(1) is listed: solid fuel-burning appliances for central heating must be installed to CSA B365 and the manufacturer's instructions.
Plumbing: storm drainage, temperature control, relief valves and water efficiency	A flat roof of 400 m² drains past a 60 m² parapet wall that is the largest adjoining vertical surface.

Loads on guards, handrails and firewalls
Firewalls must resist the larger of the normal lateral design loads or a factored lateral load of 0.5 kPa under fire conditions.
Foundations and structural material standards
Section 4.2. applies to excavations and foundations.
Environmental separation
Part 5 covers heat, air, moisture and sound transfer through assemblies that separate different environments.
HVAC installation standards and air openings
Only Sentence 6.2.1.5.(1) is listed: solid fuel-burning appliances for central heating must be installed to CSA B365 and the manufacturer's instructions.
Plumbing: storm drainage, temperature control, relief valves and water efficiency
A flat roof of 400 m² drains past a 60 m² parapet wall that is the largest adjoining vertical surface.

Usual exam traps

Using 0.9 kN for guards. That is the handrail point load; the guard point load is 1.0 kN.
Forgetting that the inward guard load is only half the outward one.
Using 43°C for showers in general. 43°C applies to care and child care settings; 49°C is the general shower valve limit.
Adding the full vertical wall area in roof drainage. Only half of the largest adjoining wall counts.

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Questions on Parts 4 to 7 provisions referenced by Part 9, in the exam format, every answer explained and cited to its article. Sign in to start; a free account gets the free questions.

Practice this chapter Small Buildings calculations

Code cited in this chapter

Based on the official 2024 Building Code Compendium on ontario.ca.

OBC Div. B 4.1.2.1. Loads and Effects
(1)Except as provided in Article 4.1.2.2., the following categories of loads, specified loads and effects shall be taken into consideration in the design of a building and its structural members and connections:
Loads and Effects — Forming Part of Sentence 4.1.2.1.(1)
Symbol | Description
D | dead load — a permanent load due to the weight of building components, as specified in Subsection 4.1.4.
E | earthquake load and effects — a rare load due to an earthquake, as specified in Subsection 4.1.8.
H | a permanent load due to lateral earth pressure, including groundwater
L | live load — a variable load due to intended use and occupancy (including loads due to cranes and the pressure of liquids in containers), as specified in Subsection 4.1.5.
L_XC | live load exclusive of crane loads,
C | live load due to cranes including self weight,
C_d | self weight of all cranes positioned for maximum effects,
C₇ | crane bumper impact load,
P | permanent effects caused by pre-stress,
S | variable load due to snow, including ice and associated rain, as specified in Article 4.1.6.2., or due to rain, as specified in Article 4.1.6.4.
T | effects due to contraction, expansion, or deflection caused by temperature changes, shrinkage, moisture changes, creep, ground settlement, or a combination thereof, and (See Note A-4.1.2.1.(1))
W | wind load — a variable load due to wind, as specified in Subsection 4.1.7.
where
(a)load means the imposed deformations (i.e. deflections, displacements or motions that induce deformations and forces in the structure), forces and pressures applied to the building structure,
(b)permanent load is a load that changes very little once it has been applied to the structure, except during repair,
(c)variable load is a load that frequently changes in magnitude, direction or location, and
(d)rare load is a load that occurs infrequently and for a short time only.
(2)Minimum specified values of the loads described in Sentence (1), as set forth in Subsections 4.1.4. to 4.1.8., shall be increased to account for dynamic effects where applicable.
(3)For the purpose of determining specified loads S, W or E in Subsections 4.1.6., 4.1.7. and 4.1.8., buildings shall be assigned an Importance Category based on intended use and occupancy, in accordance with Table 4.1.2.1. (See Note A-4.1.2.1.(3))
Open OBC Div. B 4.1.2.1. in the code viewer
OBC Div. B Table 4.1.2.1. Importance Categories for Buildings[1]
Table 4.1.2.1. Importance Categories for Buildings[1] Forming Part of Sentence 4.1.2.1.(3) Type of Building | Importance Category A Low Importance Category building is a building that represents a low direct or indirect hazard to human life in the event of structural failure. | Low A Normal Importance Category building is a building that does not meet the criteria for a Low Importance Category building, High Importance Category building or post-disaster building. | Normal A High Importance Category building is a building that provides a greater degree of safety to human life than a Normal Importance Category building. Community centres and elementary, middle and secondary schools are High Importance Category buildings. | High A post-disaster building. | Post-disaster Notes to Table 4.1.2.1. (1) See Note A-Table 4.1.2.1.
Open OBC Div. B Table 4.1.2.1. in the code viewer
OBC Div. B Table 4.1.5.3. Specified Uniformly Distributed Live Loads on an Area of Floor or Roof
Table 4.1.5.3. — Specified Uniformly Distributed Live Loads on an Area of Floor or Roof Forming Part of Sentence 4.1.5.3.(1) Use of Area of Floor or Roof | Minimum Specified Load, kPa (a) Assembly Areas Arenas[1] (areas without fixed seats that have backs) | 4.8 (a) Assembly Areas Auditoria | 4.8 (a) Assembly Areas Churches (areas without fixed seats that have backs) | 4.8 (a) Assembly Areas Dance floors | 4.8 (a) Assembly Areas Dining areas[2] | 4.8 (a) Assembly Areas Foyers and entrance halls | 4.8 (a) Assembly Areas Grandstands[1] (areas without fixed seats that have backs), reviewing stands and bleachers | 4.8 (a) Assembly Areas Gymnasia | 4.8 (a) Assembly Areas Lecture halls[1] (areas without fixed seats that have backs) | 4.8 (a) Assembly Areas Museums | 4.8 (a) Assembly Areas Promenades | 4.8 (a) Assembly Areas Rinks | 4.8 (a) Assembly Areas Stadia[1] (areas without fixed seats that have backs) | 4.8 (a) Assembly Areas Stages | 4.8 (a) Assembly Areas Theatres (areas without fixed seats that have backs) | 4.8 (a) Assembly Areas Other areas with similar uses | 4.8 (b) Classrooms and courtrooms with or without fixed seats[1] | 2.4 (c) Portions of assembly areas with fixed seats that have backs for the following uses: Arenas[1] | 2.9 (c) Portions of assembly areas with fixed seats that have backs for the following uses: Grandstands[1] | 2.9 (c) Portions of assembly areas with fixed seats that have backs for the following uses: Stadia[1] | 2.9 (d) Portions of assembly areas with fixed seats that have backs for the following uses: Churches | 2.4 (d) Portions of assembly areas with fixed seats that have backs for the following uses: Lecture halls[1] | 2.4 (d) Portions of assembly areas with fixed seats that have backs for the following uses: Theatres | 2.4 (e) Vomitories, exits, lobbies and corridors[1] | 4.8 Attics[1] Accessible by a stairway in residential occupancies only | 1.4 Attics[1] Having limited accessibility so that there is no storage of equipment or material | 0.5 Balconies Exterior | 4.8 Balconies Interior and mezzanines that could be used by an assembly of people as a viewing area[1] | 4.8 Balconies Interior and mezzanines other than above | [3] Corridors, lobbies and aisles[1] Other than those listed below | 4.8 Corridors, lobbies and aisles[1] Not more than 1 200 mm in width and all upper floor corridors of residential areas only of apartments, hotels and motels (that cannot be used by an assembly of people as a viewing area) | [3] Corridors, lobbies and aisles[1] In a Group B, Division 3 occupancy that contains sleeping accommodation for not more than 10 persons and not more than 6 occupants require assistance in evacuation in case of an emergency | 2.4 Equipment areas and service rooms including Generator rooms | 3.6[4] Equipment areas and service rooms including Mechanical equipment exclusive of elevators | 3.6[4] Equipment areas and service rooms including Machine rooms | 3.6[4] Equipment areas and service rooms including Pump rooms | 3.6[4] Equipment areas and service rooms including Transformer vaults | 3.6[4] Equipment areas and service rooms including Ventilating or air-conditioning equipment | 3.6[4] Exits and fire escapes | 4.8 Factories | 6.0[4] Footbridges | 4.8 Garages for Vehicles not exceeding 4 000 kg gross weight | 2.4 Garages for Vehicles exceeding 4 000 kg but not exceeding 9 000 kg gross weight | 6.0 Garages for Vehicles exceeding 9 000 kg gross weight[1] | 12.0 Kitchens (other than residential) | 4.8 Libraries Stack rooms | 7.2 Libraries Reading and study rooms | 2.9 Office areas[1] (not including record storage and computer rooms) located in Basement, and floors, including mezzanines, with direct access to the exterior at ground level | 4.8 Office areas[1] (not including record storage and computer rooms) located in Other floors | 2.4 Operating rooms and laboratories | 3.6 Patients’ bedrooms | 1.9 Recreation areas that cannot be used for assembly purposes including Billiard rooms | 3.6 Recreation areas that cannot be used for assembly purposes including Bowling alleys | 3.6 Recreation areas that cannot be used for assembly purposes including Pool rooms | 3.6 Residential areas (within the scope of Article 1.3.3.2. of Division A) Sleeping and living quarters in apartments, hotels, motels, boarding schools and colleges | 1.9 Residential areas (within the scope of Article 1.3.3.2. of Division A) Work areas within live/work units | 2.4 Residential areas (within the scope of Article 1.3.3.2. of Division A) Bedrooms and other areas | 1.9 Residential areas (within the scope of Article 1.3.3.2. of Division A) Other areas | 1.9 Residential areas (within the scope of Article 1.3.3.2. of Division A) Stairs within dwelling units | 1.9 Retail and wholesale areas | 4.8 Roofs[1] | 1.0[5] Sidewalks and driveways over areaways and basements[1] | 12.0[5] Storage areas, including locker rooms in apartment buildings | 4.8[4] Toilet areas | 2.4 Underground slabs with earth cover | [5] Warehouses | 4.8[4] Notes to Table 4.1.5.3.: (1) See Note A-Table 4.1.5.3. (2) See Article 4.1.5.6. (3) See Article 4.1.5.4. (4) See Sentence 4.1.5.1.(1). (5) See Article 4.1.5.5.
Open OBC Div. B Table 4.1.5.3. in the code viewer
OBC Div. B 4.1.5.14. Loads on Guards and Handrails)
(1)The minimum horizontal specified live load applied outward at the minimum required height of every required guard shall be
(a)3.0 kN/m for open viewing stands without fixed seats and for means of egress in grandstands, stadia, bleachers and arenas,
(b)1.0 kN applied at any point, so as to produce the most critical effect, for access ways to equipment platforms, contiguous stairs and similar areas where the gathering of many people is improbable, and
(c)0.75 kN/m or 1.0 kN applied at any point so as to produce the most critical effect, whichever governs for locations other than those described in Clauses (a) and (b).
(2)The minimum horizontal specified live load applied inward at the minimum required height of every required guard shall be half that specified in Sentence (1).
(3)Individual elements within the guard, including solid panels and pickets, shall be designed for a horizontal specified live load of 0.5 kN applied outward over an area of 100 mm by 100 mm located at any point on the element or elements so as to produce the most critical effect.
(4)The size of the opening between any two adjacent vertical elements within a guard shall not exceed the limits required by Part 3 when each of these elements is subjected to a horizontal specified live load of 0.1 kN applied in opposite directions in the in-plane direction of the guard so as to produce the most critical effect.
(5)The specified live loads required in Sentence (3) need not be considered to act simultaneously with the loads provided for in Sentences (1), (2), (6) and (7).
(6)The minimum specified live load applied vertically at the top of every required guard shall be 1.5 kN/m and need not be considered to act simultaneously with the horizontal specified live load provided for in Sentences (1), (3) and (7).
(7)Handrails and their supports shall be designed and constructed to withstand the following minimum specified live loads, which need not be considered to act simultaneously:
(a)0.9 kN applied at any point and in any direction for all handrails, and
(b)0.7 kN/m applied in any direction for handrails not located within dwelling units.
Open OBC Div. B 4.1.5.14. in the code viewer
OBC Div. B 4.1.5.17. Firewalls
(1)Firewalls shall be designed to resist the maximum effect due to,
(a)the appropriate lateral design loads prescribed elsewhere in this Section, or
(b)a factored lateral load of 0.5 kPa under fire conditions, as described in Sentence (2).
(2)Under fire conditions, where the fire-resistance rating of the structure is less than that of the firewall,
(a)lateral support shall be assumed to be provided by the structure on one side only, or
(b)another structural support system capable of resisting the loads imposed by a fire on either side of the firewall shall be provided.
Open OBC Div. B 4.1.5.17. in the code viewer
OBC Div. B 4.2.2.1. Subsurface Investigation
(1)A subsurface investigation, including groundwater conditions, shall be carried out by or under the direction of a professional engineer having knowledge and experience in planning and executing such investigations to a degree appropriate for the building and its use, the ground and the surrounding site conditions. (See Note A-4.2.2.1.(1))
Open OBC Div. B 4.2.2.1. in the code viewer
OBC Div. B 4.2.2.3. Field Review
(1)A field review shall be carried out by the designer or by another suitably qualified person to ascertain that the subsurface conditions are consistent with the design and that construction is carried out in accordance with the design and good engineering practice. (See Note A-4.2.2.3.(1))
(2)The review required by Sentence (1) shall be carried out
(a)on a continuous basis
(i)during the construction of all deep foundation units with all pertinent information recorded for each foundation unit,
(ii)during the installation and removal of retaining structures and related backfilling operations, and
(iii)during the placement of engineered fills that are to be used to support the foundation units, and
(b)as required, unless otherwise directed by the chief building official,
(i)in the construction of all shallow foundation units, and
(ii)in excavating, dewatering and other related works.
Open OBC Div. B 4.2.2.3. in the code viewer
OBC Div. B 4.2.2.4. Altered Subsurface Condition
(1)If, during construction, the soil, rock or groundwater is found not to be of the type or in the condition used in design and as indicated on the drawings, the design shall be reassessed by the designer.
(2)If, during construction, climatic or any other conditions change the properties of the soil, rock or groundwater, the design shall be reassessed by the designer.
Open OBC Div. B 4.2.2.4. in the code viewer

Show all 31 articles

OBC Div. B 4.2.4.4. Depth of Foundations
(1)Except as permitted in Sentence (2), the bearing surface of a foundation shall be below the level of potential damage, including damage resulting from frost action, and the foundation shall be designed to prevent damage resulting from adfreezing and frost jacking. (See Note A-4.2.4.4.(1))
(2)The bearing surface of a foundation need not be below the level of potential damage from frost where the foundation
(a)is designed against frost action, or
(b)overlies material not susceptible to frost action.
Open OBC Div. B 4.2.4.4. in the code viewer
OBC Div. B 4.2.5.2. Excavation Construction
(1)Every excavation shall be undertaken in such a manner as to prevent movement that would cause damage to adjacent buildings at all phases of construction.
(2)Material shall not be placed nor shall equipment be operated or placed in or adjacent to an excavation in a manner that may endanger the integrity of the excavation or its supports.
Open OBC Div. B 4.2.5.2. in the code viewer
OBC Div. B 4.2.5.6. Loss of Ground
(1)At all phases of excavation and construction, loss of ground due to water or any other cause shall be prevented.
Open OBC Div. B 4.2.5.6. in the code viewer
OBC Div. B 4.2.3.2. Preservation Treatment of Wood
(1)Wood exposed to soil, rock or air above the lowest anticipated groundwater table shall be treated with preservative in conformance with CAN/CSA-O80 Series, "Wood preservation," and the requirements of the appropriate standard as follows:
(a)CAN/CSA-O80.1, "Specification of treated wood,"
(b)CAN/CSA-O80.2, "Processing and treatment," or
(c)CAN/CSA-O80.3, "Preservative formulations."
(2)Wood treated as required in Sentence (1) shall be cared for as provided in Clause 4 of CAN/CSA-O80.0, "General requirements for wood preservation."
Open OBC Div. B 4.2.3.2. in the code viewer
OBC Div. B 4.3.1.1. Design Basis for Wood
(1)Buildings and their structural members made of wood shall conform to CSA O86, "Engineering design in wood."
Open OBC Div. B 4.3.1.1. in the code viewer
OBC Div. B 4.3.3.1. Design Basis for Plain, Reinforced and Pre-stressed Concrete
(1)Buildings and their structural members made of plain, reinforced and pre-stressed concrete shall conform to CSA A23.3, "Design of concrete structures." (See Note A-4.3.3.1.(1))
Open OBC Div. B 4.3.3.1. in the code viewer
OBC Div. B 4.3.4.1. Design Basis for Structural Steel
(1)Buildings and their structural members made of structural steel shall conform to CSA S16, "Design of steel structures." (See Note A-4.3.4.1.(1))
Open OBC Div. B 4.3.4.1. in the code viewer
OBC Div. B 5.1.1.1. Scope
(1)This Part is concerned with
(a)the control of condensation
(i)in building components and assemblies, and
(ii)on building materials, components and assemblies, and
(b)the transfer of heat, air, moisture and sound through
(i)building materials, components and assemblies, and
(ii)interfaces between building materials, components and assemblies. (See Note A-5.1.1.1.(1))
Open OBC Div. B 5.1.1.1. in the code viewer
OBC Div. B 5.2.1.1. Exterior Environmental Loads
(1)Above ground climatic loads shall be determined according to MMAH Supplementary Standard SB-1, "Climatic and Seismic Data."
(2)Except as provided in Sentence (3), below ground exterior environmental loads not described in MMAH Supplementary Standard SB-1, "Climatic and Seismic Data," shall be determined from existing geological and hydrological data or from site tests.
(3)Where local design and construction practice has shown soil temperature analysis to be unnecessary, soil temperatures need not be determined. (See Note A-5.2.1.1.(3))
Open OBC Div. B 5.2.1.1. in the code viewer
OBC Div. B 5.3.1.2. Properties to Resist Heat Transfer or Dissipate Heat
(1)Taking into account the conditions on either side of the environmental separator, materials and components installed to provide the required resistance to heat transfer or the means implemented to dissipate heat shall provide sufficient resistance or dissipation,
(a)to minimize surface condensation on the warm side of the component or assembly,
(b)in conjunction with other materials and components in the assembly, to minimize condensation within the component or assembly,
(c)in conjunction with systems installed for space conditioning, to meet the interior design thermal conditions for the intended occupancy, and
(d)to minimize ice damming on sloped roofs. (See Note A-5.3.1.2.(1))
Open OBC Div. B 5.3.1.2. in the code viewer
OBC Div. B 5.5.1.1. Required Resistance to Vapour Diffusion
(1)Where a building component or assembly is subjected to differentials in temperature and water vapour pressure, the properties and position of the materials and components in those components or assemblies shall be such that they control vapour diffusion or permit venting to the exterior so as to minimize accumulation of condensation in the building component or assembly.
(2)Except as provided in Sentence (3), a vapour barrier shall be installed to provide the principal resistance to water vapour diffusion.
(3)A vapour barrier is not required where it can be shown that uncontrolled vapour diffusion will not adversely affect any of
(a)the health or safety of building users,
(b)the intended use of the building, or
(c)the operation of building services.
Open OBC Div. B 5.5.1.1. in the code viewer
OBC Div. B 5.6.1.1. Required Protection from Precipitation
(1)Except as provided in Sentence (2), where a building component or assembly is exposed to precipitation, the component or assembly shall
(a)minimize ingress of precipitation into the component or assembly, and
(b)prevent ingress of precipitation into interior space.
(2)Protection from ingress of precipitation is not required where it can be shown that such ingress will not adversely affect any of
(a)the health or safety of building users,
(b)the intended use of the building, or
(c)the operation of building services.
Open OBC Div. B 5.6.1.1. in the code viewer
OBC Div. B 5.6.2.2. Accumulation and Disposal
(1)Where water, snow or ice can accumulate on a building, provision shall be made to minimize the likelihood of hazardous conditions arising from such accumulation.
(2)Where precipitation can accumulate on sloped or horizontal assemblies, provision shall be made for drainage conforming with Section 7.4.
(3)Where downspouts are provided and are not connected to a sewer, provisions shall be made to,
(a)divert the water from the building, and
(b)prevent soil erosion.
(4)Junctions between vertical assemblies, and sloped or horizontal assemblies, shall be designed and constructed to minimize the flow of water from the sloped or horizontal assembly onto the vertical assembly.
Open OBC Div. B 5.6.2.2. in the code viewer
OBC Div. B 5.9.2.4. Heat Transfer
(1)Windows, doors and skylights shall meet the heat transfer performance requirements stated in Section 5.3. (See Note A-5.3.1.2.)
(2)Except as provided in Sentence (3), all metal-framed glazed assemblies separating interior conditioned space from interior unconditioned space or exterior space shall incorporate a thermal break to minimize condensation.
(3)Metal-framed glazed assemblies need not comply with Sentence (2) where these assemblies are
(a)storm windows or doors, or
(b)windows or doors that are required to have a fire-protection ratings. (See Note A-5.9.2.4.(3))
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OBC Div. B 6.2.1.5. Installation Standards
(1)The installation of solid fuel-burning appliances for central heating systems shall comply with CSA B365, "Installation code for solid-fuel-burning appliances and equipment" and the manufacturer's installation instructions.
(2)The solid fuel-fired appliances in Sentence (1) shall conform to CSA B366.1, "Solid-fuel-fired central heating appliances."
(3)The design and installation of earth energy systems shall conform to CAN/CSA-C448.2, "Design and installation of earth energy systems for residential and other small buildings," where such systems use groundwater, submerged heat exchangers or ground heat exchangers to serve,
(a)a house with or without a secondary unit, or,
(b)a building, other than a house with or without a secondary unit, where the conditioned space is not more than 1,400 m².
(4)Except for a house with or without a secondary unit, the design and installation of earth energy systems shall conform to CAN/CSA-C448.1, "Design and installation of earth energy systems for commercial and institutional buildings," where such systems use groundwater, submerged heat exchangers or ground heat exchangers to condition a floor space area more than 1,400 m².
(5)The design and installation of solid fuel-burning stoves, ranges and space heaters, including the requirements for combustion air, shall conform to the requirements of CSA B365, "Installation code for solid-fuel-burning appliances and equipment" and the manufacturer's installation instructions.
(6)The design and installation of hydronic heating systems shall conform to
(a)CSA B214, "Installation code for hydronic heating systems," or
(b)good engineering practice appropriate to the circumstances such as described in Article 6.2.1.1.
(7)Solid fuel-burning stoves, furnaces and hydronic heating systems designed to burn solid fuels, other than coal, shall conform to the particulate emission limits of,
(a)CSA B415.1, "Performance Testing of Solid-Fuel-Burning Heating Appliances," or
(b)the "Standards of Performance for New Residential Wood Heaters," set out in Subpart AAA of Part 60 of Title 40 of the Code of Federal Regulations, published by the United States Environmental Protection Agency, as it read on March 16, 2015.
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OBC Div. B 6.3.2.9. Supply, Return, Intake and Exhaust Air Openings
(1)Supply, return and exhaust air openings located less than 2 m above the floor in rooms or spaces in buildings shall be protected by grilles having openings of a size that will not allow the passage of a 15 mm diam sphere.
(2)Outdoor air intakes shall be located so that
(a)the quality of the air entering the building complies with Sentence 6.2.1.2.(1), and
(b)they are separated a minimum distance from sources of contaminants in accordance with Table 6.3.2.9.
(3)Outdoor air intakes shall be installed not less than 0.3 m above roofs, landscape grades or other surfaces, taking into account anticipated snow accumulation levels.
(4)Exterior openings for outdoor air intakes and exhaust outlets shall be shielded from the entry of snow and rain and shall be fitted with corrosion-resistant screens of mesh having openings not larger than 15 mm, except where experience has shown that climatic conditions require larger openings to prevent the screen openings from icing over.
(5)Screens required in Sentence (4) shall be accessible for maintenance.
(6)Combustible grilles, diffusers and other devices covering supply, return, intake and exhaust openings shall comply with Article 3.6.5.7.
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OBC Div. B 6.3.2.10. Exhaust Ducts and Outlets
(1)Except as provided in Sentence (2), exhaust ducts of non-mechanical ventilating systems serving separate rooms or spaces shall not be combined.
(2)Exhaust ducts of non-mechanical ventilating systems serving similar occupancies may be combined immediately below the point of final delivery to the outdoors, such as at the base of a roof ventilator.
(3)Exhaust ducts of ventilating systems shall have provision for the removal of condensation where this may be a problem.
(4)Exhaust outlets shall be designed to prevent back draft under wind conditions.
(5)Except as permitted in Sentence (6), exhaust systems shall discharge directly to the outdoors. (See Note A-6.3.2.10.(5) and (6))
(6)Exhaust systems are permitted to exhaust into a storage garage, provided
(a)they serve rooms that are accessible only from that storage garage,
(b)the exhaust contains no contaminants that would adversely affect the air quality in the storage garage, and (See Note A-6.3.2.10.(6)(b))
(c)they are designed in accordance with Sentence 6.3.2.7.(3). (See Note A-6.3.2.10.(5) and (6))
(7)Exhaust ducts connected to laundry drying equipment shall be,
(a)independent of other exhaust ducts,
(b)designed and installed so that the entire duct can be cleaned, and
(c)constructed of smooth corrosion-resistant material. (See Note A-6.3.2.10.(7) and (8))
(8)Where collective venting of multiple installations of laundry-drying equipment is used, the ventilation system shall
(a)be connected to a common exhaust duct that is vented by one central exhaust fan,
(b)include an interlock to activate the central exhaust fan when laundry-drying equipment is in use, and
(c)be provided with make-up air. (See Note A-6.3.2.10.(7) and (8))
(9)Exhaust ducts or vents connected to laundry-drying equipment shall discharge directly to the outdoors.
(10)Except as provided in Sentence (12) and except for self-contained systems serving individual dwelling units, exhaust ducts serving rooms containing water closets, urinals, basins, showers or slop sinks shall be independent of other exhaust ducts.
(11)Except as provided in Sentence (12) and except for self-contained systems serving individual dwelling units, exhaust ducts serving rooms containing residential cooking equipment shall be independent of other exhaust ducts.
(12)Two or more exhaust systems described in Sentences (10) and (11) may be interconnected or connected with exhaust ducts serving other areas of the building, provided
(a)the connections are made at the inlet of an exhaust fan, and all interconnected systems are equipped with suitable back pressure devices to prevent the passage of odours from one system to another when the fan is not in operation, or
(b)the exhaust ducts discharge to a shaft that is served by an exhaust fan having a capacity that is equal to or greater than the combined capacity of the exhaust fans discharging to the plenum multiplied by the operation diversity factor, provided that the exhaust fan serving the shaft operates continuously. (See Note A-6.3.2.10.(12)(b))
(13)Where exhaust ducts containing air from conditioned spaces pass through or are adjacent to unconditioned spaces, the ducts shall be constructed to prevent condensation from forming on the inside or outside of the ducts.
(14)Except as provided in Sentence (15), exhaust air shall be provided at a rate not less than 24 L/s for each water closet, urinal, shower or slop sink.
(15)Except as provided in Sentence 6.3.1.1.(4), exhaust air shall be provided for fixtures in dwelling units in accordance with ANSI/ASHRAE 62.1, "Ventilation for Acceptable Indoor Air Quality."
(16)Except for wash basins (lavatories), sanitary facilities in a food premises shall be mechanically ventilated and shall be capable of exhausting air at the rate of not less than 24 L/s for each sanitary fixture listed in Sentence (17).
(17)The mechanical ventilation described in Sentence (16) applies to rooms containing water closets, urinals, basins, showers or slop sinks.
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OBC Div. B 7.1.2.2. Storm Drainage Systems
(1)Except as provided in Section 7.7., storm drainage systems and private sewers conveying storm sewage shall be connected to a public storm sewer, a public combined sewer or a designated storm water disposal location.
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OBC Div. B 7.2.10.7A. Temperature Control Devices
(1)A water distribution system supplying hot water to any bathtub, shower or hand basin that is accessible to a patient or resident in a Group B, Division 2 or 3 occupancy or a resident of a group home, home for special care or residence for adults with developmental disabilities, or children within child care facilities shall have one or more temperature gauges and control devices that are
(a)accessible only to supervisory staff, and
(b)capable of being adjusted to ensure that the temperature of the water supplied to the fixtures does not exceed 43°C.
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OBC Div. B 7.2.10.7B. Showers
(1)Except as provided for in Sentences (2) and (3), all valves supplying fixed location shower heads, shall be individually pressure-balanced or thermostatic-mixing valves, conforming to ASME A112.18.1 / CSA B125.1, "Plumbing Supply Fittings."
(2)An individually pressure-balanced or thermostatic-mixing valve is not required for shower heads having a single tempered water supply that is controlled by an automatic compensating valve conforming to CSA B125.3, "Plumbing fittings."
(3)Deck-mounted, hand-held, flexible-hose spray attachments are exempt from the thermal shock requirements of Sentences (1) and (4).
(4)Pressure-balanced, thermostatic-mixing or combination pressure-balanced and thermostatic-mixing type valves shall
(a)capable of limiting thermal shock, and
(b)designed so that the outlet temperature does not exceed 49°C or equipped with high-limit stops which shall be adjusted to a maximum hot water setting of 49°C.
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OBC Div. B 7.4.10.4. Hydraulic Loads from Roofs or Paved Surfaces
(1)Except as provided in Sentence (2), the hydraulic load in litres from a roof or paved surface is the maximum 15 min rainfall determined in conformance with MMAH Supplementary Standard SB-1, "Climatic and Seismic Data," multiplied by the sum of
(a)the area in square metres of the horizontal projection of the surface drained, and
(b)one-half the area in square metres of the largest adjoining vertical surface.
(2)Flow control roof drains may be installed, provided
(a)the maximum drain down time does not exceed 24 h,
(b)the roof structure is designed to carry the load of the stored water,
(c)one or more scuppers are installed not more than 30 m apart along the perimeter of the building so that
(i)up to 200% of the 15-minute rainfall intensity can be handled, and
(ii)the maximum depth of controlled water is limited to 150 mm,
(d)they are located not more than 15 m from the edge of the roof and not more than 30 m from adjacent drains, and
(e)there is at least one drain for each 900 m².
(3)Reserved.
(4)Where the height of the parapet is more than 150 mm or exceeds the height of the adjacent wall flashing,
(a)emergency roof overflows or scuppers described in Clause (2)(c) shall be provided, and
(b)there shall be a minimum of 2 roof drains.
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OBC Div. B 7.6.1.7. Relief Valves
(1)Every pressure vessel that is part of a plumbing system or connected to a plumbing system shall be equipped with a pressure-relief valve designed to open when the water pressure in the tank reaches the rated working pressure of the tank, and so located that the pressure in the tank shall not exceed 1,100 kPa or one-half the maximum test pressure sustained by the tank, whichever is the lesser.
(2)The hot water tank of a storage-type service water heater shall be equipped with a temperature-relief valve with a temperature-sensing element
(a)located within the top 150 mm of the tank, and
(b)designed to open and discharge sufficient water from the tank to keep the temperature of the water in the tank from exceeding 99°C under all operating conditions.
(3)A pressure-relief valve and temperature-relief valve may be combined where Sentences (1) and (2) are complied with.
(4)Indirect service water heaters shall be equipped with
(a)a pressure-relief valve, and
(b)a temperature-relief valve on every storage tank that forms part of the system.
(5)Pipes that convey water from a temperature-relief, pressure-relief, or a combined temperature- and pressure-relief valve shall
(a)be of a nominal pipe size at least equal to the NPS of the outlet of the valve,
(b)be rigid, slope downward from the valve, and terminate with an indirect connection above a floor drain, sump, or other safe location, with an air break of not more than 300 mm,
(c)have no thread at its outlet, and
(d)be capable of operating at a temperature of not less than 99°C. (See Note A-7.6.1.7.(5))
(6)The temperature-relief valve required in Clause (4)(b) shall
(a)have a temperature-sensing element located within the top 150 mm of the tank, and
(b)be designed to open and discharge sufficient water to keep the temperature of the water in the tank from exceeding 99°C under all operating conditions.
(7)No shut-off valve shall be installed on the pipe between any tank and the relief valves or on the discharge lines from such relief valves.
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OBC Div. B 7.6.4.1. Water Supply Fittings
(1)Each lavatory in a washroom with fixtures for public use shall be equipped with a device capable of automatically shutting off the flow of water when the lavatory is not in use. (See Note A-7.6.4.1.(1) and (3))
(2)An automatic compensating valve serving an individual shower head shall have a manufacturer's minimum-rated water flow rate equal to or less than the shower head it serves. (See Note A-7.6.4.1.(2))
(3)Where multiple shower heads installed in a public showering facility are served by one temperature control, each shower head shall be equipped with a device capable of automatically shutting off the flow of water when the shower head is not in use. (See Note A-7.6.4.1.(1) and (3))
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