Roofing, cladding and stucco: BCIN House Study Guide

Last updated October 22, 2026

Values this chapter turns on

min slope, asphalt shingles, normal method: 1 in 3; min slope, asphalt shingles, normal method
min eave protection up the slope: 900 mm; min eave protection up the slope
cladding clearance above finished ground: 200 mm; cladding clearance above finished ground
cladding clearance above a roof surface: 50 mm; cladding clearance above a roof surface

This chapter covers the outer skin of a house: roof coverings and flashing (Section 9.26.), exterior cladding and the two planes of rain protection (Section 9.27.), and stucco (Section 9.28.). The exam leans on numbers: minimum slopes, lap widths, flashing heights, eave protection limits and fastener counts. Most of them sit in short articles and a handful of tables.

Roofing basics, slopes and flashing

For Section 9.26., "roof" includes any platform that acts as a roof for collecting or draining rain, such as a deck over living space (OBC Div. B 9.26.1.1.). Roofing must shed water, keep water out of the assemblies and limit damage from ice damming (9.26.1.2.). Roofing nails must be corrosion resistant and long enough to go through the sheathing or 12 mm into it (9.26.2.3.).

Slopes. Table 9.26.3.1. sets minimum and maximum slopes by roofing type. Values candidates use most:

Roofing	Minimum slope
Asphalt shingles, normal application	1 in 3
Asphalt shingles, low slope application	1 in 6
Wood shingles	1 in 4
Cedar shakes	1 in 3
Profiled metal roofing	1 in 4

A 1 in 4 roof is flatter than 1 in 3, so asphalt shingles on it must use the low slope method of Subsection 9.26.8. Remember that 1 in 2 is steeper than 1 in 3. A bigger second number means a flatter roof.

Flashing. Sheet metal roof flashing minimums are in 9.26.4.2., for example 0.33 mm galvanized steel or 0.48 mm aluminum. Valleys on shingled roofs are flashed (9.26.4.3.). An open valley takes at least one layer of 600 mm sheet metal or two layers of roll roofing. At masonry walls and chimneys (9.26.4.4.), counter flashing is embedded at least 25 mm, runs at least 150 mm down and laps the base flashing at least 100 mm. Step flashing has at least a 75 mm head lap. Against other wall claddings (9.26.4.5.), flashing goes 75 mm up behind the sheathing paper and 75 mm out on the roof.

Chimney saddles (9.26.4.8.) are needed where the upper side of a chimney is more than 750 mm wide. The saddle may be left out if sheet metal flashing goes up the chimney at least one sixth of its width, but not less than 150 mm.

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Eave protection

9.26.5.1. requires eave protection on shingle, shake and tile roofs. It runs from the roof edge at least 900 mm up the slope, and to a line at least 300 mm inside the inner face of the exterior wall. It is not required:

over unheated garages, carports and porches,
where the overhang is more than 900 mm measured along the slope to the inner face of the wall,
on low slope asphalt shingle roofs built to 9.26.8.,
on slopes of 1 in 1.5 or steeper,
in areas with 3,500 or fewer degree-days.

Eave protection materials are listed in 9.26.5.2., for example Type M or S roll roofing with 100 mm laps, or self-sealing modified bituminous membranes. Underlay, where used, overlaps the eave protection by at least 100 mm and has 50 mm head and end laps (9.26.6.2.).

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Shingles and shakes

Asphalt shingles on normal slopes (Subsection 9.26.7.):

Item	Requirement
Coverage	At least 2 thicknesses
Head lap	At least 50 mm
Fasteners, 1 m shingle	At least 4, or 6 if staples have an 11 mm crown
Fastener location	25 to 40 mm from each end, at least 12 mm above cutouts
Hips and ridges	100 mm each side, lapped 150 mm

The fastener rules are in 9.26.7.4.. Low slope application (Subsection 9.26.8.) needs triple coverage except for the first 2 courses, plus continuous cement bands under each course.

Wood shingle exposure comes from Table 9.26.9.6., read by grade, length and slope. For example, No. 2 grade, 400 mm long shingles on a slope of 1 in 3 or steeper may be exposed 100 mm; on a flatter slope, 90 mm. Wood shakes may be exposed up to 190 mm (450 mm long) or 240 mm (600 mm long) (9.26.10.5.).

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Cladding and the second plane of protection

Walls enclosing residential space need a first plane of protection (the cladding) and a second plane that catches water that gets past and drains it out (9.27.2.2., 9.27.2.3.). The second plane is a drainage plane plus flashing (9.27.3.1.). Normally that means at least one layer of sheathing membrane with 100 mm laps, upper sheets over lower (9.27.3.3.). Exceptions: non-wood rigid insulating sheathing (9.27.3.4.), and face-sealed panel cladding or locked-seam metal (9.27.3.6.). With no sheathing at all, two layers of membrane are needed (9.27.3.5.).

Clearances for cladding that moisture can harm (9.27.2.4.): 200 mm above finished ground and 50 mm above a roof surface.

Flashing (9.27.3.8.) goes at horizontal cladding joints and offsets, and over openings where the drop from the eave to the top of the trim is more than one quarter of the eave overhang. It extends 50 mm up behind the membrane, slopes at least 6% outward and laps 10 mm over the element below. It ends in end-dams and a drip at least 5 mm out.

Attachment. Cladding is fastened to framing, furring or blocking (9.27.5.1.). Some products may go to sheathing only, if the sheathing is thick enough. Blocking is at least 38 x 38 mm at 600 mm o.c. Furring over sheathing is at least 19 x 38 mm. Fastener size and spacing are in Table 9.27.5.4.-A; for example, horizontal vinyl siding uses 38 mm fasteners at 400 mm o.c. Fasteners must penetrate 19 mm (shingles and shakes), 32 mm (vinyl and polypropylene) or 25 mm (others) into framing (9.27.5.7.).

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Siding types

Lumber siding (9.27.6.): drop, rustic and lapped siding at least 14.3 mm thick and at most 286 mm wide. Overlap is 1 mm per 16 mm of width, but at least 25 mm for lapped bevel siding, 9.5 mm for matched siding and 12 mm for battens (9.27.6.3.). A 140 mm bevel board works out to under 9 mm, so the 25 mm floor governs.
Metal (9.27.11.1.): steel sheet at least 0.33 mm. Aluminum sheet at least 0.58 mm, or 0.46 mm where backed.
Vinyl (9.27.12.1.): ASTM D3679. Attachment follows 9.27.5., with nails centred in the slots so the siding can move.

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Stucco

Key rules in Section 9.28.:

Item	Requirement
Clearance above finished ground	200 mm, unless over concrete or masonry (9.28.1.4.)
Coats	2 base coats and a finish coat, total at least 15 mm (9.28.6.2.)
First and second coats	At least 6 mm each; finish coat at least 3 mm
Lath laps	50 mm; corners reinforced 150 mm each side (9.28.4.5.)
Self-furring	Lath held at least 6 mm off the backing
Cold weather	At least 10°C during application and for 48 h after (9.28.6.1.)
Working time	Apply within 3 h of mixing

Sheathing is needed under stucco on wood frame unless horizontal wire or paper-backed welded wire lath is used (9.28.4.2.). Aluminum flashing must be separated from stucco (9.28.1.5.).

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Common traps

Reading 1 in 1.5 as flatter than 1 in 3. It is steeper.
Using 200 mm (ground) when the question is about a roof (50 mm).
Taking the one-sixth chimney value without checking the 150 mm minimum, or the reverse.
Applying the 1 mm per 16 mm rule without the 25 mm floor for bevel siding.

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
Roofing basics, slopes and flashing	For Section 9.26., "roof" includes any platform that acts as a roof for collecting or draining rain, such as a deck over living space.
Eave protection	Eave protection materials are listed in, for example Type M or S roll roofing with 100 mm laps, or self-sealing modified bituminous membranes.
Shingles and shakes	Wood shingle exposure comes from, read by grade, length and slope.
Cladding and the second plane of protection	Walls enclosing residential space need a first plane of protection (the cladding) and a second plane that catches water that gets past and drains it out.
Stucco	Sheathing is needed under stucco on wood frame unless horizontal wire or paper-backed welded wire lath is used.

Roofing basics, slopes and flashing
For Section 9.26., "roof" includes any platform that acts as a roof for collecting or draining rain, such as a deck over living space.
Eave protection
Eave protection materials are listed in, for example Type M or S roll roofing with 100 mm laps, or self-sealing modified bituminous membranes.
Shingles and shakes
Wood shingle exposure comes from, read by grade, length and slope.
Cladding and the second plane of protection
Walls enclosing residential space need a first plane of protection (the cladding) and a second plane that catches water that gets past and drains it out.
Stucco
Sheathing is needed under stucco on wood frame unless horizontal wire or paper-backed welded wire lath is used.

Usual exam traps

Reading 1 in 1.5 as flatter than 1 in 3. It is steeper.
Using 200 mm (ground) when the question is about a roof (50 mm).
Taking the one-sixth chimney value without checking the 150 mm minimum, or the reverse.
Applying the 1 mm per 16 mm rule without the 25 mm floor for bevel siding.

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Questions on Roofing, cladding and stucco, in the exam format, every answer explained and cited to its article. Sign in to start; a free account gets the free questions.

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Code cited in this chapter

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

OBC Div. B 9.26.1.1. Definitions
(1)For the purpose of this Section, the term "roof" shall mean sloped or near-horizontal assemblies that protect the spaces beneath them, including platforms that effectively serve as roofs with respect to the accumulation or drainage of precipitation. (See Note A-9.26.1.1.(1))
(2)For the purpose of this Section, the term "roofing" shall mean the primary covering for roofs.
Open OBC Div. B 9.26.1.1. 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 9.26.2.3. Nails
(1)Nails used for roofing shall be corrosion-resistant roofing or shingle nails conforming to
(a)ASTM F1667, "Standard Specification for Driven Fasteners: Nails, Spikes, and Staples," or
(b)CSA B111, "Wire Nails, Spikes and Staples."
(2)Nails shall have sufficient length to penetrate through or 12 mm into, roof sheathing.
(3)Nails used with asphalt roofing shall have a head diameter of not less than 9.5 mm and a shank thickness of not less than 2.95 mm.
(4)Nails used with wood shingles or shakes shall have a head diameter of not less than 4.8 mm and a shank thickness of not less than 2.0 mm and shall be stainless steel, aluminum or hot-dipped galvanized. (See Note A-9.26.2.3.(4))
Open OBC Div. B 9.26.2.3. in the code viewer
OBC Div. B Table 9.26.3.1. Roofing Types and Slope Limits
Table 9.26.3.1. — Roofing Types and Slope Limits Forming Part of Sentence 9.26.3.1.(1) Type of Roofing | Minimum Slope | Maximum Slope Asphalt Shingles Low slope application | 1 in 6 | no limit Asphalt Shingles Normal application | 1 in 3 | no limit Built-up Roofing Asphalt base (without gravel) | 1 in 25 | 1 in 2 Built-up Roofing Asphalt base (gravelled) | 1 in 50[1] | 1 in 4 Built-up Roofing Coal-tar base (gravelled) | 1 in 50[1] | 1 in 25 Built-up Roofing Cold process | 1 in 25 | 1 in 1.33 Cedar Shakes | 1 in 3 | no limit Clay Tile | 1 in 2 | no limit Glass Fibre Reinforced Polyester Roofing Panels | 1 in 4 | no limit Modified Bituminous Membranes | 1 in 50 | 1 in 4 Profiled Metal Roofing | 1 in 4[2] | no limit Roll Roofing 480 mm wide selvage asphalt roofing | 1 in 6 | no limit Roll Roofing Cold application felt | 1 in 50 | 1 in 1.33 Roll Roofing Smooth and mineral surfaced | 1 in 4 | no limit Sheet Metal Shingles | 1 in 4[2] | no limit Slate Shingles | 1 in 2 | no limit Wood Shingles | 1 in 4 | no limit Notes to Table 9.26.3.1.: (1) See Sentence 9.26.3.1.(2). (2) See Sentence 9.26.3.1.(3).
Open OBC Div. B Table 9.26.3.1. in the code viewer
OBC Div. B 9.26.4.2. Materials
(1)Sheet metal flashing shall consist of not less than
(a)1.73 mm thick sheet lead,
(b)0.33 mm thick galvanized steel,
(c)0.33 mm thick copper,
(d)0.35 mm thick zinc, or
(e)0.48 mm thick aluminum.
Open OBC Div. B 9.26.4.2. in the code viewer
OBC Div. B 9.26.4.3. Valley Flashing
(1)Where sloping surfaces of shingled roofs intersect to form a valley, the valley shall be flashed.
(2)Valley flashing shall be installed over continuous sheathing.
(3)Closed valleys shall not be used with rigid shingles on slopes of less than 1 in 1.2.
(3.1)Closed valley flashing shall consist of sheet metal, self sealing composite membranes consisting of polyethylene and bituminous material or one layer of either Type S smooth surface roll roofing or Type M mineral surface roll roofing (mineral surface down) not less than 600 mm wide, and nails shall not penetrate the flashing within 75 mm of its edge or 124 mm of the bottom of the valley centre line.
(4)Open valleys shall be flashed with at least
(a)one layer of sheet metal not less than 600 mm wide, or
(b)2 layers of roll roofing.
(5)The bottom layer of roofing required in Sentence (4) shall consist of at least Type S smooth roll roofing or Type M mineral surface roll roofing (mineral surface down) not less than 457 mm wide, centred in the valley and fastened with nails spaced not more than 450 mm o.c. located 25 mm away from the edges.
(6)The top layer of roofing required in Sentence (4) shall consist of at least Type M mineral surface roll roofing (mineral surface up), 914 mm wide, centred in the valley, applied over a 100 mm wide strip of cement along each edge of the bottom layer, and fastened with a sufficient number of nails to hold it in place until the shingles are applied.
Open OBC Div. B 9.26.4.3. in the code viewer
OBC Div. B 9.26.4.4. Intersection of Shingle Roofs and Masonry
(1)The intersection of shingle roofs and masonry walls or chimneys shall be protected with flashing.
(2)Counter flashing required in Sentence (1) shall be embedded not less than 25 mm in the masonry and shall extend not less than 150 mm down the masonry and lap the lower flashing not less than 100 mm.
(3)Flashing along the slopes of a roof described in Sentence (1) shall be stepped so that there is not less than a 75 mm head lap in both the lower flashing and counter flashing.
(4)Where the roof described in Sentence (1) slopes upwards from the masonry, the flashing shall extend up the roof slope to a point equal in height to the flashing on the masonry, but not less than 1.5 times the shingle exposure.
Open OBC Div. B 9.26.4.4. in the code viewer
OBC Div. B 9.26.4.5. Intersection of Shingle Roofs and Walls Other Than Masonry
(1)The intersection of shingle roofs and walls clad with other than masonry shall be protected with flashing.
(2)Flashing required in Sentence (1) shall be installed so that it extends up the wall not less than 75 mm behind the sheathing paper, and extends not less than 75 mm horizontally.
(3)Along the slope of the roof, the flashing required in Sentence (1) shall be stepped with not less than a 75 mm head lap.
Open OBC Div. B 9.26.4.5. in the code viewer

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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 9.26.5.1. 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 9.26.5.2. Materials
(1)Eave protection shall be laid beneath the starter strip and shall consist of
(a)No. 15 asphalt-saturated felt laid in two plies lapped 480 mm and cemented together with lap cement,
(b)Type M or S roll roofing laid with not less than 100 mm head and end laps cemented together with lap cement,
(c)glass fibre or polyester fibre coated base sheets, or
(d)self-sealing composite membranes consisting of modified bituminous coated material.
Open OBC Div. B 9.26.5.2. in the code viewer
OBC Div. B 9.26.6.2. Installation
(1)When used with shingles, underlay shall be installed parallel to the eaves with head and end lap of not less than 50 mm.
(2)The top edge of each strip of underlay referred to in Sentence (1) shall be fastened with sufficient roofing nails to hold it in place until the shingles are applied.
(3)The underlay referred to in Sentence (1) shall overlap the eave protection by not less than 100 mm. (See Article 9.26.10.2. for underlay beneath wood shakes.)
Open OBC Div. B 9.26.6.2. in the code viewer
OBC Div. B 9.26.7.1. Coverage
(1)Coverage shall be not less than 2 thicknesses of shingle over the entire roof, disregarding cutouts.
Open OBC Div. B 9.26.7.1. 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 9.26.8.1. Coverage
(1)Except for the first 2 courses, coverage shall be not less than 3 thicknesses of shingle over the entire roof, disregarding cutouts.
Open OBC Div. B 9.26.8.1. in the code viewer
OBC Div. B Table 9.26.9.6. Maximum Exposure, mm
Table 9.26.9.6. — Maximum Exposure, mm Forming Part of Sentence 9.26.9.6.(1) Roof Slope | No. 1 or A Grade Length of Shingle: 400 mm | No. 1 or A Grade Length of Shingle: 450 mm | No. 1 or A Grade Length of Shingle: 600 mm | No. 2 or B Grade Length of Shingle: 400 mm | No. 2 or B Grade Length of Shingle: 450 mm | No. 2 or B Grade Length of Shingle: 600 mm < 1 in 3 | 100 | 115 | 165 | 90 | 100 | 140 ≥ 1 in 3 | 125 | 140 | 190 | 100 | 115 | 165
Open OBC Div. B Table 9.26.9.6. in the code viewer
OBC Div. B 9.26.10.5. Exposure
(1)The exposure of wood shakes shall not exceed
(a)190 mm for shakes not less than 450 mm long, and
(b)240 mm for shakes not less than 600 mm long.
Open OBC Div. B 9.26.10.5. 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 9.27.3.1. Elements of the Second Plane of Protection
(1)The second plane of protection shall consist of a drainage plane having an appropriate inner boundary and flashing to dissipate rainwater to the exterior.
(2)Except for cladding systems conforming to Subsection 9.27.14., the inner boundary of the drainage plane shall comply with Articles 9.27.3.2. to 9.27.3.6.
(3)The protection provided by the second plane of protection shall be maintained
(a)at wall penetrations created by the installation of components and services such as windows, doors, ventilation ducts, piping, wiring and electrical outlets, and
(b)at the interface with other wall assemblies.
(4)Flashing material and its installation shall comply with Articles 9.27.3.7. and 9.27.3.8.
Open OBC Div. B 9.27.3.1. 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 9.27.3.4. Insulating Sheathing in Lieu of Sheathing Membrane
(1)Where non-wood-based rigid exterior insulating sheathing, or exterior insulating sheathing with an integral sheathing membrane is installed, a separate sheathing membrane is not required.
(2)Where insulating sheathing is installed as provided in Sentence (1),
(a)sheathing panels subject to moisture deterioration shall be sealed at all joints, and
(b)the joints of sheathing panels not subject to moisture deterioration shall be
(i)sealed at all joints, or
(ii)lapped or tongue and groove, and detailed to ensure drainage of water to the exterior. (See Note A-9.27.3.4.(2))
Open OBC Div. B 9.27.3.4. in the code viewer
OBC Div. B 9.27.3.6. Face Sealed Cladding
(1)Sheathing membrane is permitted to be omitted beneath cladding when the joints in the cladding are formed to effectively prevent the passage of wind and rain in conformance with Sentence (2) or (3), as applicable.
(2)Cladding consisting of sheets of plywood, hardboard, OSB, waferboard or fibre cement is considered to meet the requirements of Sentence (1), provided the cladding is applied so that
(a)all edges are directly supported by framing,
(b)the vertical joints between adjacent sheets are sealed and
(i)covered with battens,
(ii)shiplapped, or
(iii)otherwise matched to provide weathertight joints, and
(c)the horizontal joints between adjacent sheets are sealed and
(i)shiplapped, or
(ii)otherwise matched to provide weathertight joints.
(3)Metal siding consisting of sheets of metal is considered to meet the requirements of Sentence (1) where the joints between sheets are of the locked-seam type.
Open OBC Div. B 9.27.3.6. in the code viewer
OBC Div. B 9.27.3.5. Sheathing Membranes in Lieu of Sheathing
(1)Except as provided in Article 9.27.3.6., where no sheathing is used, at least 2 layers of sheathing membrane shall be applied beneath the cladding. (See Article 9.23.17.1. and Note A-9.27.3.5.(1))
(2)All joints in the sheathing membrane required in Sentence (1) shall occur over framing, and the membrane shall be fastened to the framing with roofing nails or staples spaced not more than 150 mm along the edges of the outer layer of sheathing membrane.
(3)Wall sheathing is permitted to be used in lieu of one layer of sheathing membrane required in Sentence (1), and the thickness need not conform to Table 9.23.17.2.-A.
Open OBC Div. B 9.27.3.5. in the code viewer
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.
Open OBC Div. B 9.27.2.4. 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 9.27.5.1. Attachment
(1)Except as permitted by Sentences (2) to (5), cladding shall be fastened to the framing members or furring members, or to blocking between the framing members.
(2)Vertical lumber, stucco lath or reinforcing, vertically applied vinyl siding, vertically applied insulated vinyl siding, and polypropylene siding are permitted to be attached to sheathing only where the sheathing consists of not less than
(a)14.3 mm lumber,
(b)12.5 mm plywood, or
(c)12.5 mm OSB or waferboard.
(3)Vertically applied metal siding and wood shingles and shakes are permitted to be attached to the sheathing only where the sheathing consists of not less than
(a)14.3 mm lumber,
(b)7.5 mm plywood, or
(c)7.5 mm OSB or waferboard.
(4)Where wood shingles or shakes are applied to sheathing which is not suitable for attaching the shingles or shakes, the shingles or shakes are permitted to be attached to a wood lath not less than 38 mm by 9.5 mm thick securely nailed to the framing and applied as described in Article 9.27.7.5.
(5)Cladding, trim and furring members are permitted to be attached to the web fastening strips of flat wall insulating concrete form units using screws in accordance with Sentence 9.27.5.4.(2)
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OBC Div. B Table 9.27.5.4-A. Attachment of Cladding to Wood Framing, Furring Members or Blocking — Forming Part of Sentence 9.27.5.4.(1)
Table 9.27.5.4.-A Attachment of Cladding to Wood Framing, Furring Members or Blocking — Forming Part of Sentence 9.27.5.4.(1) Forming Part of Sentence 9.27.5.4.(1) Type of Cladding | Minimum Nail or Staple Length, mm[1] | Minimum Number of Nails or Staples | Maximum Nail or Staple Spacing, mm o.c. Wood trim | 51 | N/A | 600 Lumber siding or horizontal siding made from sheet metal | 51 | N/A | 600 Metal cladding | 38 | N/A | 600 (nailed to framing) 400 (nailed to sheathing only) Wood shakes up to 200 mm in width | 51 | 2 | N/A Wood shakes over 200 mm in width | 51 | 3 | N/A Wood shingles up to 200 mm in width | 32 | 2 | N/A Wood shingles over 200 mm in width | 32 | 3 | N/A Horizontally applied Vinyl and insulated vinyl siding | 38 | N/A | 400[2] Vertically Applied Vinyl and insulated vinyl siding | 38 | N/A | 300 Polypropylene siding | 38 | N/A | 400[2] Panel- or sheet-type cladding up to 7 mm thick | 38 | N/A | 150 (along edges) Panel- or sheet-type cladding over 7 mm thick | 51 | N/A | 300 (along intermediate supports) Notes to Table 9.27.5.4.-A: (1) The minimum fastener length need not exceed the minimum fastener penetration depth required by Article 9.27.5.7. (2) The maximum spacing of 400 mm o.c. applies to nails and staples used to attach horizontally applied vinyl, insulated vinyl and polypropylene siding, unless a greater spacing is permitted in an evaluation report prepared by an accredited certification organization.
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OBC Div. B 9.27.5.7. Penetration of Fasteners
(1)Fasteners for shakes and shingles shall penetrate through the nail-holding base or not less than 19 mm into the framing.
(2)Fasteners for vinyl cladding, insulated vinyl cladding and polypropylene cladding shall penetrate through the nail-holding base or not less than 32 mm into the framing.
(3)Fasteners for cladding other than that described in Sentences (1) and (2) shall penetrate through the nail-holding base or not less than 25 mm into the framing.
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OBC Div. B 9.27.6.2. Thickness and Width
(1)Drop, rustic, novelty, lapped board and vertical wood siding shall be not less than 14.3 mm thick and not more than 286 mm wide.
(2)Bevel siding shall be
(a)not less than 5 mm thick at the top, and
(b)not less than
(i)12 mm thick at the butt for siding 184 mm or less in width, and
(ii)14.3 mm thick at the butt for siding wider than 184 mm.
(3)Bevel siding shall be not more than 286 mm wide.
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OBC Div. B 9.27.6.3. Joints
(1)Lumber siding shall prevent water from entering at the joints by the use of lapped or matched joints or by vertical wood battens.
(2)Siding shall overlap not less than 1 mm per 16 mm width of lumber, but not less than
(a)9.5 mm for matched siding,
(b)25 mm for lapped bevel siding, or
(c)12 mm for vertical battens.
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OBC Div. B 9.27.11.1. Material Standards
(1)Steel sheet cladding, including horizontal and vertical strip steel siding, flashing and trim accessories, shall
(a)have a minimum thickness of 0.33 mm, and
(b)conform to CSSBI 23 M, "Standard for Residential Steel Cladding." (See Note A-9.27.11.1.(1))
(2)Horizontal and vertical strip aluminum siding, including flashing and trim accessories, shall conform to CAN/CGSB-93.2-M, "Prefinished Aluminum Siding, Soffits and Fascia, for Residential Use." (See Note A-9.27.11.1.(2) and (3))
(3)Aluminum sheet cladding shall conform to CAN/CGSB-93.1-M, "Sheet, Aluminum Alloy, Prefinished, Residential," and shall have a thickness of not less than 0.58 mm, except that siding supported by backing or sheathing shall have a thickness of not less than 0.46 mm. (See Note A-9.27.11.1.(2) and (3))
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OBC Div. B 9.27.12.1. Material Standards
(1)Vinyl siding shall conform to ASTM D3679, "Standard Specification for Rigid Poly (Vinyl Chloride) (PVC) Siding."
(2)Insulated vinyl siding shall conform to ASTM D7793, "Standard Specification for Insulated Vinyl Siding."
(3)Rigid vinyl soffits shall conform to ASTM D4477, "Standard Specification for Rigid (Unplasticized) Poly(Vinyl Chloride) (PVC) Soffit."
(4)Where vinyl siding, insulated vinyl siding or rigid vinyl soffits are required to have a flame-spread rating, the rating shall be determined in accordance with CAN/ULC-S102.2, "Standard Method of Test for Surface Burning Characteristics of Flooring, Floor Coverings, and Miscellaneous Materials and Assemblies."
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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 9.28.4.5. Application of Stucco Lath
(1)Stucco lath shall be applied with the long dimension horizontal.
(2)Horizontal and vertical joints in stucco lath shall be lapped not less than 50 mm.
(3)End joints of stucco lath shall be staggered and shall occur over framing members.
(4)External corners of stucco lath shall be reinforced with a vertical strip of lath or reinforcing extending not less than 150 mm on both sides of the corner, or the lath or reinforcing shall extend around corners not less than 150 mm.
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OBC Div. B 9.28.6.1. Low Temperature Conditions
(1)The base for stucco shall be maintained above freezing.
(2)Stucco shall be maintained at a temperature of not less than 10°C during application and for not less than 48 h afterwards.
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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 9.28.1.5. Flashing and Caulking
(1)Flashing and caulking used with stucco shall conform to Subsections 9.27.3. and 9.27.4., except that if aluminum flashing is used, it shall be separated from the stucco by an impervious membrane or coating. (See Article 9.7.6.2. for caulking around window frames.)
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