Envelope, roofing, cladding and finishes (Part 9) (Small Buildings)

Last updated October 22, 2026

Values this chapter turns on

min slope, asphalt shingles, normal application: 1 in 3; min slope, asphalt shingles, normal application
minimum eave protection up the roof slope: 900 mm; minimum eave protection up the roof slope
waterproof finish in a shower stall, above floor: 1.8 m; waterproof finish in a shower stall, above floor
clearance of moisture-prone cladding to ground: 200 mm; clearance of moisture-prone cladding to ground

This chapter covers the building envelope and finishes in Part 9: insulation, air and vapour barriers and where low permeance materials may go, roofing, cladding and stucco, interior wall finishes and flooring. These rules apply to offices, stores and apartments built under Part 9 just as they do to houses. Expect lookups of a single number and a few table readings, especially roof slopes and the outboard insulation ratio.

Insulation, air barriers and vapour barriers

Any wall, ceiling or floor separating conditioned space from unconditioned space, outdoor air or the ground needs three things: thermal insulation, an air barrier system and a vapour barrier. The materials must also sit in the right order OBC Div. B 9.25.1.1.. The amount of insulation in Part 9 is a performance statement. Actual values come from Part 12 and SB-12, covered in a later chapter.

Installation points: insulation must fill the full width and length of each cavity OBC Div. B 9.25.2.3.. It must run the full height of foundation walls around a basement or heated crawl space. Where exposed to weather and damage, it is covered with at least 6 mm treated plywood or 12 mm parging on lath.

The two barriers do different jobs, and the definitions show it. An air barrier system stops air movement. A vapour barrier controls the diffusion of water vapour. The air barrier must be continuous, including through the basement OBC Div. B 9.25.3.1.. Joints in sheet air barriers are sealed, or lapped at least 100 mm and clamped. Penetrations, hatches and sump pit covers are sealed or weatherstripped OBC Div. B 9.25.3.3..

A vapour barrier goes on the warm side OBC Div. B 9.25.4.3. and has a dry cup permeance of no more than 60 ng/(Pa x s x m2) OBC Div. B 9.25.4.2.. Where interior use will make a lot of moisture, the assembly is designed to Part 5 instead.

Low permeance materials on the cold side

Foam sheathing or a similar panel can trap moisture if it sits on the cold side of the wall. Article 9.25.5.1 decides when the location rule applies. It applies to sheet or panel materials with very low air leakage and a permeance under 60 OBC Div. B 9.25.5.1.. Thin wood-based sheathing (12.5 mm or less) is exempt. So is a material with a permeance of at least 30 and a thermal resistance of at least 0.7, where the site has under 6,000 degree-days. If the rule applies, the material must go on the warm face, outboard of a vented air space, or where the outboard to inboard thermal resistance ratio meets Table 9.25.5.2 OBC Div. B 9.25.5.2.. For walls, a vented air space must be at least 10 mm deep behind the cladding.

Heating degree-days (from SB-1)	Minimum outboard to inboard ratio
Under 5,000	0.20
5,000 to 5,999	0.30
6,000 to 6,999	0.35

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Roofing

Roofs must shed water, keep water out of assemblies and limit ice-dam leaks. Compliance is by Section 9.26 or by Part 5 OBC Div. B 9.26.1.2.. Minimum and maximum slopes come from Table 9.26.3.1 OBC Div. B 9.26.3.1.. The key rows:

Roofing	Minimum slope
Asphalt shingles, normal application	1 in 3
Asphalt shingles, low slope application	1 in 6
Wood shingles	1 in 4
Modified bituminous membrane	1 in 50

Gravelled built-up roofs may go flatter if roof drains sit at the low points. Profiled metal designed for low slopes may also go flatter.

Eave protection is required on shingle, shake and tile roofs. It runs at least 900 mm up the slope and at least 300 mm inside the inner face of the exterior wall OBC Div. B 9.26.5.1.. It is not needed over unheated garages, carports and porches, where the overhang exceeds 900 mm, on asphalt shingles installed to Subsection 9.26.8 (the method that gives at least 3 thicknesses of shingle over the roof), on slopes of 1 in 1.5 or steeper, or where there are 3,500 or fewer degree-days.

Strip shingles need at least 4 fasteners per 1 m shingle, or 6 staples with an 11 mm crown OBC Div. B 9.26.7.4.. A chimney wider than 750 mm on its upper side needs a saddle, unless the sheet metal flashing option is used OBC Div. B 9.26.4.8.. Downspouts that do not go to a sewer need extensions that carry water away and prevent erosion OBC Div. B 9.26.18.2..

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Cladding and stucco

Walls that enclose residential space, or space that directly serves it, need two planes of protection OBC Div. B 9.27.2.2.. The first plane is the cladding. The second is a drainage plane with flashing that catches and drains what gets past OBC Div. B 9.27.2.3.. At least one layer of sheathing membrane goes under siding, stucco or veneer, with 100 mm laps and upper sheets over lower ones OBC Div. B 9.27.3.3..

Flashing is needed at horizontal joints, offsets and changes of substrate. It is not needed where the upper cladding laps the lower by at least 25 mm. It turns up at least 50 mm behind the membrane, slopes at least 6% outward, has end dams and ends in a drip OBC Div. B 9.27.3.8.. Cladding that moisture can damage, such as OSB, plywood or untreated wood, stays 200 mm above finished ground and 50 mm above a roof OBC Div. B 9.27.2.4..

Stucco rule	Value	Article
Clearance above ground (not over concrete or masonry)	200 mm	9.28.1.4
Coats	2 base coats plus a finish coat	9.28.6.2
Total thickness from face of lath	15 mm	9.28.6.2

See OBC Div. B 9.28.1.4. and OBC Div. B 9.28.6.2.. Sheathing can be left out under stucco only where horizontal wire or paper-backed welded wire lath is used OBC Div. B 9.28.4.2..

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Interior finishes and flooring

Finishes must also meet the fire and sound rules of 9.10 and 9.11 OBC Div. B 9.29.1.1.. Waterproof finish heights are a frequent question OBC Div. B 9.29.2.1.:

Location	Waterproof finish to at least
Shower stall	1.8 m above the floor
Bathtub with shower	1.2 m above the rim
Bathtub without shower	400 mm above the rim

Tile around tubs and showers goes on moisture-resistant backing OBC Div. B 9.29.10.4..

Finished flooring is required in residential occupancies OBC Div. B 9.30.1.1.. Bathrooms, kitchens, public entrance halls, laundries and general storage areas need water-resistant flooring OBC Div. B 9.30.1.2.. Panel-type underlay is required in four cases: under resilient flooring, parquet, tile or carpet on lumber subfloors; under resilient flooring, parquet or carpet on panel subfloors with unsupported edges; under tile set in adhesive; and under resilient flooring on waferboard or strandboard OBC Div. B 9.30.2.1.. Underlay is at least 6 mm thick OBC Div. B 9.30.2.2..

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Common traps

The air barrier and the vapour barrier are different defined terms with different jobs. Polyethylene can do both, but the code tests them separately.
In the outboard ratio, use the degree-day row for the site and count everything outboard of the material's inner face.
Asphalt shingles on a 1 in 4 roof are allowed only by the low slope method.
Eave protection exemptions are a closed list. If none of them fits, eave protection is required, whatever the occupancy.
Waterproof finish in a shower stall is measured from the floor. For tubs it is measured from the rim.

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
Insulation, air barriers and vapour barriers	Any wall, ceiling or floor separating conditioned space from unconditioned space, outdoor air or the ground needs three things: thermal insulation, an air barrier system and a…
Roofing	Roofs must shed water, keep water out of assemblies and limit ice-dam leaks.
Cladding and stucco	Walls that enclose residential space, or space that directly serves it, need two planes of protection.
Interior finishes and flooring	Tile around tubs and showers goes on moisture-resistant backing.

Insulation, air barriers and vapour barriers
Any wall, ceiling or floor separating conditioned space from unconditioned space, outdoor air or the ground needs three things: thermal insulation, an air barrier system and a…
Roofing
Roofs must shed water, keep water out of assemblies and limit ice-dam leaks.
Cladding and stucco
Walls that enclose residential space, or space that directly serves it, need two planes of protection.
Interior finishes and flooring
Tile around tubs and showers goes on moisture-resistant backing.

Usual exam traps

The air barrier and the vapour barrier are different defined terms with different jobs. Polyethylene can do both, but the code tests them separately.
In the outboard ratio, use the degree-day row for the site and count everything outboard of the material's inner face.
Asphalt shingles on a 1 in 4 roof are allowed only by the low slope method.
Eave protection exemptions are a closed list. If none of them fits, eave protection is required, whatever the occupancy.
Waterproof finish in a shower stall is measured from the floor. For tubs it is measured from the rim.

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Questions on Envelope, roofing, cladding and finishes (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 9.25.1.1. Scope and Application
(1)This Section is concerned with heat, air and water vapour transfer and measures to control condensation.
(2)All walls, ceilings and floors separating conditioned space from unconditioned space, the exterior air or the ground shall be
(a)provided with
(i)thermal insulation conforming to Subsection 9.25.2.,
(ii)an air barrier system conforming to Subsection 9.25.3., and
(iii)a vapour barrier conforming to Subsection 9.25.4., and
(b)constructed in such a way that the properties and relative position of all materials conform to Subsection 9.25.5. (See Note A-9.25.1.1.(2))
(3)Insulation and sealing of heating and ventilating ducts shall conform to Sections 9.32., 9.33.
Open OBC Div. B 9.25.1.1. in the code viewer
OBC Div. B 9.25.2.3. Installation of Thermal Insulation
(1)Insulation shall be installed so that there is a reasonably uniform insulating value over the entire face of the insulated area.
(2)Insulation shall be applied to the full width and length of the space between furring or framing.
(3)Except where the insulation provides the principal resistance to air leakage, thermal insulation shall be installed so that at least one face is in full and continuous contact with an element with low air permeance. (See Note A-9.25.2.3.(3))
(4)Insulation shall be installed over the full height of foundation walls enclosing a basement or heated crawl space.
(5)Insulation around concrete slabs-on-ground shall be located so that heat from the building is not restricted from reaching the ground beneath the perimeter, where exterior walls are not supported by footings extending below frost level.
(6)Where insulation is exposed to the weather and subject to mechanical damage, it shall be protected with not less than
(a)6 mm preservative-treated plywood, or
(b)12 mm cement parging on wire lath applied to the exposed face and edge.
(7)Except as permitted in Sentence (7.1), insulation and vapour barrier located in areas where it may be subject to mechanical damage shall be protected by a covering such as gypsum board, plywood, particleboard, OSB, waferboard or hardboard.
(7.1)In unfinished basements, the protection required in Sentence (7) need not be provided for mineral fibre insulation, provided it is covered with a membrane which complies with the requirements of Section 9.25.4.
(8)Insulation in factory-built buildings shall be installed so that it will not become dislodged during transportation.
Open OBC Div. B 9.25.2.3. in the code viewer
OBC Div. A 1.4.1.2.(1) Air barrier system
Air barrier system means the assembly installed to provide a continuous barrier to the movement of air.
Open OBC Div. A 1.4.1.2.(1) in the code viewer
OBC Div. A 1.4.1.2.(1) Vapour barrier
Vapour barrier means the elements installed to control the diffusion of water vapour. (See Note A-1.4.1.2.(1))
Open OBC Div. A 1.4.1.2.(1) in the code viewer
OBC Div. B 9.25.3.1. Required Barrier to Air Leakage
(1)Wall, ceiling and floor assemblies that separate conditioned space from unconditioned space or from the ground shall be constructed so as to include an air barrier system that will provide a continuous barrier to air leakage
(a)from the interior of the building into wall, floor, attic or roof spaces sufficient to prevent excessive moisture condensation in such spaces during the winter, and
(b)from the exterior or the ground inward sufficient to
(i)prevent moisture condensation on the room side during winter,
(ii)ensure comfortable conditions for the occupants, and
(iii)minimize the ingress of soil gas. (See Note A-9.25.3.1.(1))
(2)The continuity of the air barrier system shall extend throughout the basement.
Open OBC Div. B 9.25.3.1. in the code viewer
OBC Div. B 9.25.3.3. Continuity of the Air Barrier System
(1)Where the air barrier system consists of an air-impermeable panel-type material, all joints shall be sealed to prevent air leakage.
(2)Where the air barrier system consists of flexible sheet material, all joints shall be
(a)sealed with compatible material such as tape or flexible sealant, or
(b)except as required by Sentence (2.1), lapped not less than 100 mm and clamped, such as between framing members, furring or blocking, and rigid panels.
(2.1)Where an air barrier system consisting of flexible sheet material is installed at locations where it is not supported by an interior finish, such as a behind a bathtub, shower enclosure or fireplace, the continuity of the air barrier shall be maintained by sealing its joints.
(3)Where an interior wall meets an exterior wall, ceiling, floor or roof required to be provided with air barrier protection, the air barrier system shall extend across the intersection and shall be sealed in accordance with Sentences (1) and (2).
(4)Where an interior wall projects through a ceiling or extends to become an exterior wall, spaces in the wall shall be blocked to provide continuity across those spaces with the air barrier system in the abutting walls or ceiling by
(a)sealing each air barrier to the blocking, or
(b)wrapping each air barrier around the transition and sealing in accordance with Sentences (1) and (2).
(5)Where an interior floor projects through an exterior wall to become an exterior floor,
(a)the air barrier of the wall under the floor shall be continuous with or sealed to the subfloor or the air barrier on the underside of the floor,
(b)the air barrier of the wall above the floor shall be continuous with or sealed to the subfloor or the air barrier on the top of the floor, and
(c)the spaces between floor joists shall be blocked and sealed.
(5.1)Where a header wrap is used as an air barrier, it shall be sealed or lapped to the wall air barrier above and below in accordance with Sentences (1) and (2).
(6)Penetrations of the air barrier system, such as those created by the installation of electrical wiring, electrical boxes, piping or ductwork, shall be sealed to maintain the integrity of the air barrier system over the entire surface.
(6.1)Where an interior air barrier is penetrated by doors, windows and other fenestration, the air barrier shall be sealed to the door frame or window frame with
(a)compatible tape, or
(b)spray foam insulation.
(6.2)Where an exterior air barrier is penetrated by doors, windows and other fenestration, the air barrier shall be sealed to the door frame or window frame with
(a)compatible flexible flashing material,
(b)caulking, or
(c)spray foam insulation.
(7)Where access hatches and sump pit covers are installed through assemblies constructed with an air barrier system, they shall be weatherstripped around their perimeters to prevent air leakage.
(8)Clearances between chimneys or gas vents and the surrounding construction that would permit air leakage from within the building into a wall or attic or roof space shall be sealed by noncombustible material to prevent such leakage and shall be sealed to the air barrier with tape or another compatible material, and to the vent with high temperature caulking in accordance with the manufacturer's installation instructions.
(9)Reserved.
(10)Sump pit covers shall be sealed to maintain continuity of the air barrier system.
Open OBC Div. B 9.25.3.3. in the code viewer
OBC Div. B 9.25.4.3. Installation of Vapour Barriers
(1)Products installed to function as the vapour barrier shall protect the warm side of wall, ceiling and floor assemblies.
(2)Where different products are used for the vapour barrier and the insulation, the vapour barrier shall be installed sufficiently close to the warm side of the insulation to prevent condensation at design conditions. (See Note A-9.25.4.3.(2) and A-9.25.5.1.(1))
(3)Where the same product is used for the vapour barrier and the insulation, the product shall be installed sufficiently close to the warm side of the assembly to prevent condensation at design conditions. (See Note A-9.25.4.3.(2) , A-9.25.5.1.(1) and A-9.25.5.2.)
Open OBC Div. B 9.25.4.3. in the code viewer
OBC Div. B 9.25.4.2. Vapour Barrier Materials
(1)Except as provided in Sentence (2), vapour barriers shall have a permeance not greater than 60 ng/(Pa×s×m²) measured in accordance with ASTM E96 / E96 M, "Standard Test Methods for Water Vapor Transmission of Materials," using the desiccant method (dry cup).
(2)Thermally insulated foundation wall assemblies are permitted to be constructed with variable-permeance vapour barriers having a permeance not greater than 60 ng/(Pa×s×m²) using the desiccant method (dry cup) and greater than 300 ng/(Pa×s×m²) using the water method (wet cup) measured in accordance with ASTM E96 / E96 M, "Standard Test Methods for Water Vapor Transmission of Materials." (See Note A-9.25.4.2.(2))
(3)Where the intended use of the interior space will result in high moisture generation, the assembly shall be designed according to Part 5. (See Note A-9.25.4.2.(3))
(4)Where polyethylene is installed to serve only as the vapour barrier, it shall comply with Clause 4.4, Thermal Stability, and Clause 5.7, Oxidative Induction Time, of CAN/CGSB-51.34-M, "Vapour Barrier, Polyethylene Sheet for Use in Building Construction."
(5)Membrane-type vapour barriers other than polyethylene shall conform to the requirements of CAN/CGSB-51.33-M, "Vapour Barrier, Sheet, Excluding Polyethylene, for Use in Building Construction."
(6)Membrane-type vapour barriers other than polyethylene that are susceptible to deterioration under prolonged exposure to direct ultraviolet radiation shall
(a)be covered, or
(b)only be installed in locations that are not exposed to direct ultraviolet radiation after the completion of construction. (See Note A-9.25.4.2.(6))
(7)Where a coating is applied to gypsum board to function as the vapour barrier, the permeance of the coating shall be determined in accordance with CAN/CGSB-1.501-M, "Method for Permeance of Coated Wallboard."
(8)Where insulation functions as the vapour barrier, it shall be sufficiently thick so as to meet the requirement of Sentence (1).
Open OBC Div. B 9.25.4.2. in the code viewer

Show all 31 articles

OBC Div. B 9.25.5.1. General
(1)Except as provided in Sentences (2) to (4), sheet and panel-type materials incorporated into assemblies described in Article 9.25.1.1. shall conform to Article 9.25.5.2. where
(a)the material has
(i)an air leakage characteristic less than 0.1L/(s × m^2) at 75 Pa, and
(ii)a water vapour permeance less than 60 ng/(Pa×s×m²) when measured in accordance with ASTM E96 / E96 M, "Standard Test Methods for Water Vapor Transmission of Materials," using the desiccant method (dry cup), and (See Note A-9.25.5.1.(1) (a)(ii))
(b)the intended use of the interior space where the materials are installed will not result in high moisture generation. (See Note A-9.25.5.1.(1))
(2)Where the intended use of the interior space will result in high moisture generation, the assembly shall be designed according to Part 5.
(3)Wood-based sheathing materials not more than 12.5 mm thick and complying with Article 9.23.17.2. need not comply with Sentence (1). (See Note A-9.25.5.1.(3))
(4)Where a material has a water vapour permeance not less than 30 ng/( Pa × s × m^2 ) and a thermal resistance not less than 0.7 ( Pa × s × m^2 ) and the heating degree-days of the building location are less than 6000, the assembly need not comply with Sentence (1).
Open OBC Div. B 9.25.5.1. in the code viewer
OBC Div. B 9.25.5.2. Position of Low Permeance Materials
(1)Sheet and panel-type materials described in Article 9.25.5.1. shall be installed
(a)on the warm face of the assembly, (See also Article 9.25.4.2.)
(b)at a location where the ratio between the total thermal resistance of all materials outboard of its innermost impermeable surface and the total thermal resistance of all materials inboard of that surface is not less than that required by Table 9.25.5.2., or
(c)outboard of an air space that is vented to the outdoors.
(2)For walls, the air space described in Clause (1)(c) shall be drained and ventilated and shall be not less than 10 mm deep behind the cladding, over the full height and width of the wall.
Open OBC Div. B 9.25.5.2. in the code viewer
OBC Div. B 9.26.1.2. Required Protection
(1)Roofs shall be protected with roofing, including flashing, installed so as to
(a)effectively shed water,
(b)prevent the ingress of water and moisture into building assemblies and occupied space, and
(c)minimize the ingress of water due to ice damming into building assemblies.
(2)Compliance with Sentence (1) shall be demonstrated by conforming to
(a)this Section, or
(b)Part 5.
Open OBC Div. B 9.26.1.2. in the code viewer
OBC Div. B 9.26.3.1. Slope
(1)Except as provided in Sentences (2) and (3), the slopes on which roof coverings may be applied shall conform to Table 9.26.3.1.
(2)Asphalt and gravel or coal tar and gravel roofs may be constructed with lower slopes than required in Sentence (1) when effective drainage is provided by roof drains located at the lowest points on the roofs.
(3)Profiled metal roof cladding systems specifically designed for low-slope applications are permitted to be installed with lower slopes than required in Sentence (1), provided they are installed in conformance with the manufacturer's written recommendations.
(4)Except where back-slope will not adversely affect adjacent supported or supporting constructions due to water ingress, roofs and constructions that effectively serve as roofs shall be constructed with sufficient slope away from
(a)exterior walls, and
(b)guards that are connected to the roof, or to a construction that effectively serves as a roof, by more than pickets or posts.
(See Notes A-9.26.1.1.(1), A-9.26.4.1. and A-9.27.3.8.(4))
(5)The slope required in Sentence (4) shall be sufficient to maintain a positive slope
(a)after expected shrinkage of the building frame, where these surfaces are supported by exterior walls and on exterior columns, and (See Note A-9.27.3.8.(4))
(b)once design loading is taken into consideration, where these surfaces are cantilevered from exterior walls.
Open OBC Div. B 9.26.3.1. in the code viewer
OBC Div. B 9.26.5.1. Required Eave Protection
(1)Except as provided in Sentence (2), eave protection shall be provided on shingle, shake or tile roofs, extending from the edge of the roof a minimum of 900 mm up the roof slope to a line not less than 300 mm inside the inner face of the exterior wall.
(2)Eave protection is not required
(a)over unheated garages, carports and porches,
(b)where the roof overhang exceeds 900 mm measured along the roof slope from the edge of the roof to the inner face of the exterior wall.
(c)on roofs of asphalt shingles installed in accordance with Subsection 9.26.8.,
(d)on roofs with slopes of 1 in 1.5 or greater, or
(e)in regions with 3,500 or fewer degree-days.
Open OBC Div. B 9.26.5.1. in the code viewer
OBC Div. B 9.26.7.4. Fasteners
(1)Except as provided in Sentence (2), shingles shall be fastened with at least 4 nails or staples for 1 m wide shingles so that no nails or staples are exposed.
(2)Where staples with an 11 mm crown are used, shingles shall be fastened with at least 6 staples.
(3)Fasteners may be reduced for narrower shingles in proportion to the width of the shingle or when shingles incorporating interlocking devices are used.
(4)Fasteners referred to in Sentences (1) and (2) shall be located 25 mm to 40 mm from each end of each strip shingle with other fasteners equally spaced between them.
(5)Fasteners referred to in Sentences (1) and (2) shall be located not less than 12 mm above the tops of the cutouts.
Open OBC Div. B 9.26.7.4. in the code viewer
OBC Div. B 9.26.4.8. Chimney Saddles
(1)Except as otherwise permitted in Sentence (5), chimney saddles shall be installed where the upper side of a chimney on a sloping roof is more than 750 mm wide.
(2)Chimney saddles shall be covered with sheet metal or roofing material of weight and quality equivalent to the roofing.
(3)Saddles shall be flashed where they intersect the roof.
(4)The intersection of the saddle and the chimney shall be flashed and counterflashed as described in Article 9.26.4.4.
(5)A chimney saddle need not be installed if the intersection between the chimney and roof is protected by sheet metal flashing that extends up the chimney to a height equal to at least one-sixth the width of the chimney, but not less than 150 mm, and up the roof slope to a point equal in height to the flashing on the chimney, but not less than 1.5 times the shingle exposure.
(6)Flashing described in Sentence (5) at the chimney shall be counterflashed as required by Article 9.26.4.4.
Open OBC Div. B 9.26.4.8. in the code viewer
OBC Div. B 9.26.18.2. Downspouts
(1)Where downspouts are provided and are not connected to a sewer, extensions shall be provided to carry rainwater away from the building in a manner which will prevent soil erosion.
Open OBC Div. B 9.26.18.2. in the code viewer
OBC Div. B 9.27.2.2. Minimum Protection from Precipitation Ingress
(1)Reserved.
(2)Reserved.
(3)Reserved.
(4)Exterior walls exposed to precipitation shall be protected against precipitation ingress by an exterior cladding assembly consisting of a first plane of protection and a second plane of protection, where such walls enclose spaces of residential occupancy or spaces that directly serve spaces of residential occupancy. (See Note A-9.27.2.2.(4))
(5)Reserved.
(6)Reserved.
Open OBC Div. B 9.27.2.2. in the code viewer
OBC Div. B 9.27.2.3. First and Second Planes of Protection
(1)Where walls required to provide protection from precipitation comprise cladding assemblies with first and second planes of protection,
(a)the first plane of protection shall
(i)consist of cladding, with appropriate trim, accessory pieces and fasteners, and
(ii)be designed and constructed to minimize the passage of rain and snow into the wall by minimizing holes and managing precipitation ingress caused by kinetic energy of raindrops, surface tension, capillarity, gravity, and air pressure differences, (See Subsection 9.27.4.)
(b)the second plane of protection shall be designed and constructed to (See Subsection 9.27.3.)
(i)intercept all rain and snow that gets past the first plane of protection, and
(ii)effectively dissipate any rain or snow to the exterior, and
(c)the protection provided by the first and second planes of protection shall be maintained
(i)at wall penetrations created by the installation of components and services such as windows, doors, ventilation ducts, piping, wiring and electrical outlets, and
(ii)at the interface with other wall assemblies.
Open OBC Div. B 9.27.2.3. in the code viewer
OBC Div. B 9.27.3.3. Required Sheathing Membrane and Installation
(1)Except as provided in Articles 9.27.3.4. to 9.27.3.6., at least one layer of sheathing membrane shall be applied beneath siding, stucco or masonry veneer.
(2)Sheathing membrane required in Sentence (1) shall be applied so that joints are lapped not less than 100 mm.
(3)Where sheathing membrane required in Sentence (1) is applied horizontally, the upper sheets shall overlap the lower sheets.
Open OBC Div. B 9.27.3.3. in the code viewer
OBC Div. B 9.27.3.8. Flashing Installation
(1)Except as provided in Sentence (2), flashing shall be installed at
(a)every horizontal junction between cladding elements,
(b)every horizontal offset in the cladding, and
(c)every horizontal line where the cladding substrates change and where
(i)the substrates differ sufficiently for stresses to be concentrated along that line, or
(ii)the installation of the cladding on the lower substrate may compromise the drainage of moisture from behind the cladding above. (See Note A-9.27.3.8.(1))
(2)Flashing need not be installed as described in Sentence (1)
(a)where the upper cladding elements overlap the lower cladding elements by not less than 25 mm,
(b)where,
(i)the cladding above and below the joint is installed outboard of a drained and vented air space, and (See Clause 9.27.2.2.(1)(a))
(ii)the horizontal detail is constructed so as to minimize the ingress of precipitation into the air space, or
(c)at horizontal construction joints in stucco, where
(i)the joint is finished with an expansion-contraction strip, and
(ii)the cladding is installed outboard of a drained and vented air space. (See Clause 9.27.2.2.(1)(a))
(3)Flashing shall be installed over exterior wall openings where the vertical distance from the bottom of the eave to the top of the trim is more than one-quarter of the horizontal overhang of the eave. (See Note A-9.27.3.8.(3))
(4)Flashing described in Sentences (1) and (3) shall
(a)extend not less than 50 mm upward inboard of the sheathing membrane or sheathing installed in lieu of the sheathing membrane, (See Article 9.27.3.4.)
(b)have a slope of not less than 6% toward the exterior after the expected shrinkage of the building frame,
(c)terminate at each end with an end-dam
(i)with a height in millimetres not less than 25 mm or 1/10 the value of the 1-in-5 driving rain wind pressure in Pa, and
(ii)at the height defined in Subclause (c)(i), extending to the face of the adjacent cladding,
(d)lap not less than 10 mm vertically over the building element below, and
(e)terminate in a drip offset not less than 5 mm outward from the outer face of the building element below. (See Note A-9.27.3.8.(4))
(5)Where the sills of windows and doors installed in exterior walls are not self-flashing, flashing shall be installed between the underside of the window or door and the wall construction below. (See Note A-9.27.3.8.(5))
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OBC Div. B 9.27.2.4. Protection of Cladding from Moisture
(1)A clearance of not less than 200 mm shall be provided between finished ground and cladding that is adversely affected by moisture, such as untreated wood, plywood, OSB, waferboard and hardboard.
(2)A clearance of not less than 50 mm shall be provided between a roof surface and cladding that is adversely affected by moisture, such as untreated wood, plywood, OSB, waferboard and hardboard.
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OBC Div. B 9.28.1.4. Clearance Over Ground Level
(1)Stucco shall be not less than 200 mm above finished ground level except when it is applied over concrete or masonry.
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OBC Div. B 9.28.6.2. Number of Coats and Total Thickness
(1)Stucco shall be applied with at least 2 base coats and one finish coat, providing a total thickness of not less than 15 mm, measured from the face of the lath or face of the masonry where no lath is used.
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OBC Div. B 9.28.4.2. No Sheathing Required
(1)Sheathing need not be provided beneath stucco where not less than 1.19 mm diam galvanized wire is applied horizontally to the framing at vertical intervals of not more than 150 mm, or where paper-backed welded wire metal lath is used.
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OBC Div. B 9.29.1.1. Fire Protection and Sound Control
(1)A wall or ceiling finish shall also conform to the appropriate requirements in Sections 9.10. and 9.11. in addition to the requirements in this Section.
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OBC Div. B 9.29.2.1. Where Required
(1)Waterproof finish shall be provided to a height of not less than
(a)1.8 m above the floor in shower stalls,
(b)1.2 m above the rims of bathtubs equipped with showers, and
(c)400 mm above the rims of bathtubs not equipped with showers.
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OBC Div. B 9.29.10.4. Moisture Resistant Backing
(1)Ceramic and plastic tile installed on walls around bathtubs or showers shall be applied over moisture-resistant backing.
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OBC Div. B 9.30.1.1. Required Finished Flooring
(1)Finished flooring shall be provided in all residential occupancies.
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OBC Div. B 9.30.1.2. Water Resistance
(1)Finished flooring in bathrooms, kitchens, public entrance halls, laundry and general storage areas shall consist of resilient flooring, felted-synthetic-fibre floor coverings, concrete, terrazzo, ceramic tile, mastic or other types of flooring providing similar degrees of water resistance. (See Note A-9.30.1.2.(1))
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OBC Div. B 9.30.2.1. Required Underlay
(1)A panel-type underlay shall be provided under resilient flooring, parquet flooring, ceramic tile, felted-synthetic-fibre floor coverings or carpeting laid over lumber subflooring. (See Sentence 9.30.3.2.(1))
(2)Panel-type underlay shall be provided under resilient flooring, parquet flooring, felted-synthetic-fibre floor coverings or carpeting on panel-type subflooring whose edges are unsupported. (See Article 9.23.15.3.)
(3)Panel-type underlay shall be provided under ceramic tile applied with adhesive.
(4)Panel-type underlay shall be provided under resilient flooring on waferboard or strandboard subflooring.
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OBC Div. B 9.30.2.2. Materials and Thickness
(1)Panel-type underlay shall be not less than 6 mm thick and shall conform to
(a)ANSI A208.1, "Particleboard,"
(b)CAN/CGSB-11.3-M, "Hardboard,"
(c)ANSI/HPVA HP-1, "American National Standard for Hardwood and Decorative Plywood,"
(d)CSA O121, "Douglas fir plywood,"
(e)CSA O151, "Canadian softwood plywood,"
(f)CSA O153, "Poplar plywood," or
(g)CSA O437.0, "OSB and Waferboard."
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