Last updated
When this shows up on the exam
Spatial separation is a favourite calculation on the House and Small Buildings exams. A typical question gives a wall size, a distance to a lot line or street, and an occupancy, then asks for the maximum window area, or the fire-resistance rating and cladding the wall needs. Houses use Subsection 9.10.15. Other Part 9 buildings use Subsection 9.10.14. Small Buildings questions also use the Part 3 tables in Subsection 3.2.3.
The method
- Pick the right rules. A building with only dwelling units and no unit above another (or a house with a secondary suite) uses OBC Div. B 9.10.15.1.OBC Div. B 9.10.15.1. Application(1) This Subsection applies to (a) buildings that contain only dwelling units and have no dwelling unit above another dwelling unit, and (b) houses with a secondary suite including their common spaces. (See Note A-9.10.15.1.(1)) Other Part 9 buildings use 9.10.14.1.OBC Div. B 9.10.14.1. Application(1) This Subsection applies to buildings other than those to which Subsection 9.10.15, applies. (2) This Subsection does not apply to a house with a secondary suite. Part 3 buildings use 3.2.3.1.OBC Div. B 3.2.3.1. Limiting Distance and Area of Unprotected Openings(1) Except as permitted by Articles 3.2.3.10. to 3.2.3.12., the area of unprotected openings in an exposing building face for the applicable limiting distance shall be not more than the value determined in accordance with (a) Table 3.2.3.1.-B or Table 3.2.3.1.-C for an exposing building face conforming to Article…
- Find the area of the exposing building face. Take the wall facing one direction, from finished ground level to the uppermost ceiling, so length times height (9.10.15.2.(1)OBC Div. B 9.10.15.2. Area and Location of Exposing Building Face(1) The area of an exposing building face shall be (a) taken as the exterior wall area facing in one direction on any side of a building, and (b) calculated as (i) the total area measured from the finished ground level to the uppermost ceiling, (ii) the area for each fire compartment, where a building is divided into…, 3.2.3.2.(1)OBC Div. B 3.2.3.2. Area of Exposing Building Face(1) Except as permitted by Sentences (2) and (3), the area of an exposing building face shall be calculated as the total area of exterior wall facing in one direction on any side of a building measured from the finished ground level to the uppermost ceiling. (2) If a building is divided by fire separations into fire…).
- Find the limiting distance. Measure at right angles from the face to the property line, to the centre line of a street, lane or public thoroughfare, or to an imaginary line between two buildings on the same property (limiting distance definitionOBC Div. A 1.4.1.2.(1) Limiting distanceLimiting distance means the distance from an exposing building face to a property line, the centre line of a street, lane or public thoroughfare, or to an imaginary line between 2 buildings or fire compartments on the same property, measured at right angles to the exposing building face.).
- Adjust the limiting distance if needed. With no adequate fire department, the required limiting distance is doubled for a house that is not sprinklered throughout (9.10.15.3A.OBC Div. B 9.10.15.3A. Inadequate Firefighting Facilities(1) Where there is no fire department or where a fire department is not organized, trained and equipped to meet the needs of the community, the required limiting distance determined from Sentences 9.10.15.4.(2) and (5) and Sentence 9.10.15.5.(6), shall be doubled for a building that is not sprinklered throughout.). The article ties this to the limiting distance found with the portions method of 9.10.15.4.(2)OBC Div. B 9.10.15.4. Glazed Openings in Exposing Building Face(1) Except as provided in Sentences (6) to (9), the maximum area of glazed openings in an exposing building face shall (a) conform to Table 9.10.15.4., (b) conform to Subsection 3.2.3. as if the glazed openings were unprotected openings, or (c) where the limiting distance is not less than 1.2 m, be equal to or less…. In practice you read each portion's column at half its actual distance.
- Read the table. The row heading is a maximum face area, so use the first row equal to or larger than your face. Neither the articles nor the table notes say intermediate values may be interpolated, so use the column for the next lower limiting distance. For houses use Table 9.10.15.4.OBC Div. B Table 9.10.15.4. Maximum Aggregate Area of Glazed Openings, % of Exposing Building Face AreaTable 9.10.15.4. — Maximum Aggregate Area of Glazed Openings, % of Exposing Building Face Area Forming Part of Subclause 9.10.15.2.(1)(b)(iii) and Sentences 9.10.15.4.(1) and (2) Maximum Total Area of Exposing Building Face , m² | Limiting Distance : Less than 1.2 m | Limiting Distance : 1.2 m | Limiting Distance …; for other Part 9 buildings, Table 9.10.14.4.OBC Div. B Table 9.10.14.4. Residential, business and personal services, and low-hazard industrialTable 9.10.14.4 — Residential, business and personal services, and low-hazard industrial Forming Part of Sentence 9.10.14.4.(1) Maximum Total Area of Exposing Building Face, m² | Limiting Distance, <1.2 m | Limiting Distance, 1.2 m | Limiting Distance, 1.5 m | Limiting Distance, 2 m | Limiting Distance, 2.5 m |… (two parts: residential, business and low-hazard industrial; mercantile and medium-hazard industrial).
- Multiply. Percentage times face area gives the maximum aggregate opening area in m².
- Check the other routes. Where the limiting distance is at least 1.2 m, a house may instead use the limiting distance squared (9.10.15.4.(1)(c)OBC Div. B 9.10.15.4. Glazed Openings in Exposing Building Face(1) Except as provided in Sentences (6) to (9), the maximum area of glazed openings in an exposing building face shall (a) conform to Table 9.10.15.4., (b) conform to Subsection 3.2.3. as if the glazed openings were unprotected openings, or (c) where the limiting distance is not less than 1.2 m, be equal to or less…). Other Part 9 buildings use the limiting distance squared, or half of it for mercantile and medium-hazard industrial (9.10.14.4.(1)(c)OBC Div. B 9.10.14.4. Openings in Exposing Building Face(1) Except as provided in Sentences (6) to (10) and Sentence 9.10.14.6.(1), the maximum aggregate area of unprotected openings in an exposing building face shall (a) conform to Table 9.10.14.4., (b) conform to Subsection 3.2.3., or (c) where the limiting distance is not less than 1.2 m, be equal to or less than (i)…). The Part 3 tables are a third route. Any one route that works is acceptable.
- Apply increases. Glass block, or full sprinkler protection of the rooms behind the face, allows up to twice the area (9.10.15.4.(7)OBC Div. B 9.10.15.4. Glazed Openings in Exposing Building Face(1) Except as provided in Sentences (6) to (9), the maximum area of glazed openings in an exposing building face shall (a) conform to Table 9.10.15.4., (b) conform to Subsection 3.2.3. as if the glazed openings were unprotected openings, or (c) where the limiting distance is not less than 1.2 m, be equal to or less…).
- Check construction. For a house, a face with a limiting distance under 0.6 m needs a 45 min rating plus metal or noncombustible cladding, or one of the other cladding or tested-wall options listed (9.10.15.5.(2)OBC Div. B 9.10.15.5. Construction of Exposing Building Face of Houses(1) Except as provided in Sentences (1.1), (2), (4) and (6), each exposing building face and any exterior wall located above an exposing building face that encloses an attic or roof space shall be constructed in conformance with Subsection 9.10.8., (a) for the exposing building face as a whole, or (b) for any number…). Openings closer than 1.2 m need rated closures (9.10.15.4.(8)OBC Div. B 9.10.15.4. Glazed Openings in Exposing Building Face(1) Except as provided in Sentences (6) to (9), the maximum area of glazed openings in an exposing building face shall (a) conform to Table 9.10.15.4., (b) conform to Subsection 3.2.3. as if the glazed openings were unprotected openings, or (c) where the limiting distance is not less than 1.2 m, be equal to or less…). For other Part 9 buildings, the permitted opening percentage sets the rating and cladding in Table 9.10.14.5.OBC Div. B Table 9.10.14.5. Minimum Construction Requirements for Exposing Building Faces — Forming Part of Sentence 9.10.14.5.(1)Table 9.10.14.5 — Minimum Construction Requirements for Exposing Building Faces — Forming Part of Sentence 9.10.14.5.(1) Forming Part of Sentence 9.10.14.5.(1) Occupancy Classification of Building | Maximum Area of Unprotected Openings Permitted, % of Exposing Building Face Area | Minimum Required Fire-Resistance…; Part 3 uses Table 3.2.3.7.OBC Div. B Table 3.2.3.7. Minimum Construction Requirements for Exposing Building FacesTable 3.2.3.7 — Minimum Construction Requirements for Exposing Building Faces Forming Part of Sentences 3.1.6.9.(5) and 3.2.3.7.(1) to (4) Occupancy Classification of Building or Fire Compartment | Maximum Area of Unprotected Openings Permitted, % of Exposing Building Face Area | Minimum Required Fire-Resistance…
Worked example 1: house side wall
A detached house wall is 9 m long and 5 m from finished ground to the uppermost ceiling. It is 4 m from the side lot line.
| Step | Working | Result |
|---|---|---|
| Face area | 9 m × 5 m | 45 m² |
| Table row | 45 m² is not over 50 m² | 50 m² row |
| Table column | limiting distance 4 m | 4 m column |
| Value | Table 9.10.15.4., 50 row, 4 m column | 28% |
| Table route | 0.28 × 45 m² | 12.6 m² |
| Squared route | 4 m × 4 m | 16 m² |
The table allows 12.6 m². The limiting-distance-squared route allows 16 m², so the designer may provide up to 16 m² of glazing (OBC Div. B 9.10.15.4.(1)OBC Div. B 9.10.15.4. Glazed Openings in Exposing Building Face(1) Except as provided in Sentences (6) to (9), the maximum area of glazed openings in an exposing building face shall (a) conform to Table 9.10.15.4., (b) conform to Subsection 3.2.3. as if the glazed openings were unprotected openings, or (c) where the limiting distance is not less than 1.2 m, be equal to or less…).
Worked example 2: house facing a lane
A rear wall 8 m long and 5.5 m high is 1.5 m from the lot line. Beyond the lot line is a public lane 5 m wide.
| Step | Working | Result |
|---|---|---|
| Limiting distance | 1.5 m + (5 m ÷ 2) | 4.0 m |
| Face area | 8 m × 5.5 m | 44 m² |
| Table value | 50 row, 4 m column | 28% |
| Table route | 0.28 × 44 m² | 12.3 m² |
Measuring only to the lot line (1.5 m) would give 8%, or 3.5 m². That is the most common error on lane and street questions.
Worked example 3: Part 3 office, not sprinklered
A Group D office is not sprinklered. One wall is 15 m long and 4 m high, with a limiting distance of 2 m.
| Step | Working | Result |
|---|---|---|
| Face area | 15 m × 4 m | 60 m² |
| L/H ratio | 15 ÷ 4 | 3.75, so the "3:1 to 10:1" line |
| Table value | Table 3.2.3.1.-B, 60 row, 3:1 to 10:1, 2 m | 10% |
| Aggregate | 0.10 × 60 m² | 6.0 m² |
| Largest single opening | Table 3.2.3.1.-A, 2.0 m | 1.88 m² |
Table 3.2.3.1.-BOBC Div. B Table 3.2.3.1-B. Area of Unprotected Openings for Groups A, C, D, and F, Division 3 Occupancies, %Table 3.2.3.1.-B — Area of Unprotected Openings for Groups A, C, D, and F, Division 3 Occupancies, % Forming Part of Article 3.2.3.1. Exposing Building Face, Maximum Area, m² | Ratio (L/H or H/L)[1] | Limiting Distance, 0 m | Limiting Distance, 1.2 m | Limiting Distance, 1.5 m | Limiting Distance, 2 m | Limiting… applies to unsprinklered Groups A, C, D and F, Division 3. The note to the table says to use whichever ratio is greater, L/H or H/L. Because the limiting distance is 2 m or less, each individual opening is also capped (3.2.3.1.(5)OBC Div. B 3.2.3.1. Limiting Distance and Area of Unprotected Openings(1) Except as permitted by Articles 3.2.3.10. to 3.2.3.12., the area of unprotected openings in an exposing building face for the applicable limiting distance shall be not more than the value determined in accordance with (a) Table 3.2.3.1.-B or Table 3.2.3.1.-C for an exposing building face conforming to Article…, Table 3.2.3.1.-AOBC Div. B Table 3.2.3.1-A. Maximum Concentrated Area of Unprotected OpeningsTable 3.2.3.1.-A Maximum Concentrated Area of Unprotected Openings Forming Part of Sentence 3.2.3.1.(5) Limiting Distance, m | Maximum Area of Individual Unprotected Openings, m² 1.2 | 0.35 1.5 | 0.78 2.0 | 1.88). Between 1.2 m and 2 m the formula 0.24 × ((2 × LD) − 1.2)² gives the cap directly: at 1.8 m it is 0.24 × 2.4² = 1.38 m². Openings serving one room must be at least 2 m apart.
Worked example 4: rating and cladding for a Part 3 face
A Group C building is sprinklered throughout. A wall is 25 m by 6 m (150 m²) with a limiting distance of 4 m. Table 3.2.3.1.-DOBC Div. B Table 3.2.3.1-D. Area of Unprotected Opening for Groups A, B, C, D and F, Division 3 Occupancies, %Table 3.2.3.1.-D — Area of Unprotected Opening for Groups A, B, C, D and F, Division 3 Occupancies, % Forming Part of Sentence 3.1.6.9.(5) and Article 3.2.3.1. Exposing Building Face, Maximum Area, m² | Limiting Distance, 0 m | Limiting Distance, 1.2 m | Limiting Distance, 1.5 m | Limiting Distance, 2 m | Limiting…, "150 or more" row, 4 m column, gives 30%, so 45 m². In Table 3.2.3.7.OBC Div. B Table 3.2.3.7. Minimum Construction Requirements for Exposing Building FacesTable 3.2.3.7 — Minimum Construction Requirements for Exposing Building Faces Forming Part of Sentences 3.1.6.9.(5) and 3.2.3.7.(1) to (4) Occupancy Classification of Building or Fire Compartment | Maximum Area of Unprotected Openings Permitted, % of Exposing Building Face Area | Minimum Required Fire-Resistance…, 30% falls in the band over 25 to 50, so the face needs a 45 min rating and noncombustible cladding. The cladding waiver in 3.2.3.7.(4)OBC Div. B 3.2.3.7. Construction of Exposing Building Face(1) Except as provided by Sentences (3) and (4) and Articles 3.2.3.10. and 3.2.3.11., the fire-resistance rating, construction and cladding for exposing building faces of buildings or fire compartments of Group A, B, C, D or Group F, Division 3 occupancy classification shall comply with Table 3.2.3.7. (2) Except as… needs a limiting distance greater than 5 m, so it does not help here.
Common mistakes
- Measuring to the lot line instead of the centre line of the street or lane.
- Measuring to the far side of the street instead of its centre line.
- Rounding the face area down to a smaller row, or the limiting distance up to a larger column.
- Interpolating between columns when nothing in the articles or tables provides for it.
- Forgetting the limiting-distance-squared route, which often beats the table.
- Using the full limiting distance squared for a mercantile building (it gets half).
- Forgetting to halve the effective limiting distance of each portion where there is no adequate fire department.
- Doubling the actual limiting distance instead of the required one.
- Forgetting the 2x increase for sprinklers or glass block, or applying it twice.
- With portions of a house face, reading the row for the portion area instead of the total face area (9.10.15.4.(2)OBC Div. B 9.10.15.4. Glazed Openings in Exposing Building Face(1) Except as provided in Sentences (6) to (9), the maximum area of glazed openings in an exposing building face shall (a) conform to Table 9.10.15.4., (b) conform to Subsection 3.2.3. as if the glazed openings were unprotected openings, or (c) where the limiting distance is not less than 1.2 m, be equal to or less…).
- Using the actual window percentage in Table 9.10.14.5. or 3.2.3.7. instead of the permitted percentage.
- Using the wrong L/H ratio line, or the wrong Part 3 table for the occupancy and sprinkler status.
Find it fast in the code PDF
Bookmark Division B > Part 9 > Section 9.10 > Subsection 9.10.15 for houses and Subsection 9.10.14 for other Part 9 buildings. For Part 3, bookmark Division B > Part 3 > Section 3.2 > Subsection 3.2.3. Useful Ctrl+F phrases:
- "Maximum Aggregate Area of Glazed Openings" (house table)
- "the limiting distance squared"
- "Inadequate Firefighting Facilities"
- "Maximum Concentrated Area of Unprotected Openings"
- "Area of Unprotected Openings for Groups A, C, D"
- "Minimum Construction Requirements for Exposing Building Faces"
- "centre line of a street, lane or public thoroughfare"
Drill these questions
Calculation questions in the exam format, each worked and cited. Pick your exam; sign in to start, a free account gets the free questions.
Code cited in this method
Based on the official 2024 Building Code Compendium on ontario.ca.
© King's Printer for Ontario, 2024. Reproduced with permission.
OBC Div. B 9.10.15.1. Application
Open OBC Div. B 9.10.15.1. in the code viewer(1)This Subsection applies to
(a)buildings that contain only dwelling units and have no dwelling unit above another dwelling unit, and
(b)houses with a secondary suite including their common spaces. (See Note A-9.10.15.1.(1))
OBC Div. B 9.10.14.1. Application
Open OBC Div. B 9.10.14.1. in the code viewer(1)This Subsection applies to buildings other than those to which Subsection 9.10.15, applies.
(2)This Subsection does not apply to a house with a secondary suite.
OBC Div. B 3.2.3.1. Limiting Distance and Area of Unprotected Openings
Open OBC Div. B 3.2.3.1. in the code viewer(1)Except as permitted by Articles 3.2.3.10. to 3.2.3.12., the area of unprotected openings in an exposing building face for the applicable limiting distance shall be not more than the value determined in accordance with
(a)Table 3.2.3.1.-B or Table 3.2.3.1.-C for an exposing building face conforming to Article 3.2.3.2. of a building or fire compartment which is not sprinklered, or
(b)Table 3.2.3.1.-D or Table 3.2.3.1.-E for an exposing building face conforming to Article 3.2.3.2. of a sprinklered fire compartment that is part of a building which is sprinklered in conformance with Section 3.2. (See Note A-3) (See also Article 3.1.18.3.)
(2)The area of the unprotected openings in an exposing building face shall be the aggregate area of unprotected openings expressed as a percentage of the area of the exposing building face in Table 3.2.3.1.-B, 3.2.3.1.-C, 3.2.3.1.-D or 3.2.3.1.-E. (See Sentence 3.2.3.2.(1))
(3)For the purpose of determining the type of construction and cladding and the fire-resistance rating of an exterior wall,
(a)the exposing building face shall be taken as the projection of the exterior wall onto a vertical plane located so that no portion of the exterior wall of the building or of a fire compartment, if the fire compartment complies with the requirements of Article 3.2.3.2., is between the vertical plane and the line to which the limiting distance is measured, and
(b)the area of unprotected openings shall be determined from Table 3.2.3.1.-B, 3.2.3.1.-C, 3.2.3.1.-D or 3.2.3.1.-E.
(4)For the purpose of determining the actual percentage of unprotected openings permitted in an exterior wall, the location of the exposing building face is permitted to be taken at a vertical plane located so that there are no unprotected openings between the vertical plane and the line to which the limiting distance is measured. (See Note A-3.2.3.1.(4))
(5)Except for buildings that are sprinklered, where the limiting distance is 2 m or less, individual unprotected openings in an exposing building face shall be no greater than
(a)the area stated in Table 3.2.3.1.-A, or
(b)where the limiting distance equal to or greater than 1.2 m, the area calculated by
Area =
Area = 0.24[((2 × LD) − 1.2)^2]
where
Area = area of the unprotected opening, and
LD = limiting distance.
(6)The spacing between individual unprotected openings described in Sentence (5) that serve a single room or space described in Sentence (7) shall not be less than
(a)2 m horizontally of another unprotected opening that is on the same exposing building face and serves the single room or space, or
(b)2 m vertically of another unprotected opening that serves the single room or space, or another room or space on the same storey.
(7)For the purpose of Sentence (6), "single room or space" means a room or space that
(a)is not divided by a wall,
(b)is divided by
(i)a wall that extends less than 1.5 m from the interior face of the exterior wall, or
(ii)a partial height wall, or
(c)consists of two or more stacked spaces that are on the same storey.
(8)If a building has any storey that is not sprinklered and firefighting facilities cannot reach it within 10 min of the alarm being received, the required limiting distance shall be doubled.
(9)If the surface temperature on the unexposed surface of a wall assembly exceeds the temperature limit of a standard fire test as permitted by Article 3.1.7.2., an allowance shall be made for the radiation from the hot unexposed wall surface by adding an equivalent area of unprotected opening to the area of actual openings as follows:
A_C = A + (A_E × F_EO)
where
A_C = corrected area of unprotected openings including actual and equivalent openings,
A = actual area of unprotected openings,
A_F = area of exterior surface of the exposing building face, exclusive of openings, on which the temperature limit of the standard test is exceeded, and
F_EO = an equivalent opening factor derived from the following expression:
F_EO = ((T_u + 273)^4)/((T_e + 273)^4)
T_u = average temperature in degrees Celsius of the unexposed wall surface at the time the required fire-resistance rating is reached under test conditions,
T_e = 892°C for a fire-resistance rating not less than 45 min, 927°C for a fire-resistance rating not less than 1 h, and 1,010°C for a fire-resistance rating not less than 2 h.
(10)Unless a closure used to protect an opening in an exposing building face has a protective performance equivalent to that required for the wall assembly in which it is located, an equivalent area of unprotected opening, determined in accordance with the procedures of Sentence (9) shall be added to the greater of
(a)the actual area of unprotected openings, or
(b)the corrected area of unprotected openings.
(11)The required limiting distance for an exposing building face is permitted to be measured to a point beyond the property line that is not the centre line of a street, lane or public thoroughfare if
(a)the owners of the properties on which the limiting distance is measured and the municipality enter into an agreement in which such owners agree that,
(i)each owner covenants that, for the benefit of land owned by the other covenantors, the owner will not construct a building on his or her property unless the limiting distance for exposing building faces in respect of the proposed construction is measured in accordance with the agreement,
(ii)the covenants contained in the agreement are intended to run with the lands, and the agreement shall be binding on the parties and their respective heirs, executors, administrators, successors and assigns,
(iii)the agreement shall not be amended or deleted from title without the consent of the municipality, and
(iv)they will comply with such other conditions as the municipality considers necessary, including indemnification of the municipality by the other parties, and
(b)the agreement referred to in Clause (a) is registered against the title of the properties to which it applies.
(12)Where an agreement referred to in Sentence (11) is registered against the title of a property, the limiting distance for exposing building faces shall be measured to the point referred to in the agreement.
OBC Div. B 9.10.15.2. Area and Location of Exposing Building Face
Open OBC Div. B 9.10.15.2. in the code viewer(1)The area of an exposing building face shall be
(a)taken as the exterior wall area facing in one direction on any side of a building, and
(b)calculated as
(i)the total area measured from the finished ground level to the uppermost ceiling,
(ii)the area for each fire compartment, where a building is divided into fire compartments by fire separations with fire-resistance ratings not less than 45 min, or
(iii)where Table 9.10.15.4. is used to determine the maximum aggregate area of glazed openings, the area of any number of individual portions of the exposing building face. (See Note A-9.10.15.4.(2))
(2)Reserved.
(3)For the purpose of using Table 9.10.15.4. to determine the maximum aggregate area of glazed openings in an irregularly shaped or skewed exterior wall, the location of the exposing building face shall be taken as a vertical plane located so that there are no glazed openings between the vertical plane and the line to which the limiting distance is measured. (See Note A-3.2.3.1.(4))
(4)In determining the required cladding-sheathing assembly and fire-resistance rating for an irregularly shaped or skewed exterior wall, the location of the exposing building face shall be taken as a vertical plane located so that no portion of the actual exposing building face is between the vertical plane and the line to which the limiting distance is measured. (See Article 9.10.15.5. and Note A-3.2.3.1.(4).)
(5)The required limiting distance for an exposing building face is permitted to be measured to a point beyond the property line that is not the centre line of a street, lane or public thoroughfare if,
(a)the owners of the properties on which the limiting distance is measured and the municipality enter into an agreement in which such owners agree that,
(i)each owner covenants that, for the benefit of land owned by the other covenantors, the owner will not construct a building on his or her property unless the limiting distance for exposing building faces in respect of the proposed construction is measured in accordance with the agreement,
(ii)the covenants contained in the agreement are intended to run with the lands, and the agreement shall be binding on the parties and their respective heirs, executors, administrators, successors and assigns,
(iii)the agreement shall not be amended or deleted from title without the consent of the municipality, and
(iv)they will comply with such other conditions as the municipality considers necessary, including indemnification of the municipality by the other parties, and
(b)the agreement referred to in Clause (a) is registered against the title of the properties to which it applies.
(6)Where an agreement referred to in Sentence (5) is registered against the title of a property, the limiting distance for exposing building faces in respect of the construction of any buildings on the property shall be measured to the point referred to in the agreement.
OBC Div. B 3.2.3.2. Area of Exposing Building Face
Open OBC Div. B 3.2.3.2. in the code viewer(1)Except as permitted by Sentences (2) and (3), the area of an exposing building face shall be calculated as the total area of exterior wall facing in one direction on any side of a building measured from the finished ground level to the uppermost ceiling.
(2)If a building is divided by fire separations into fire compartments, the area of exposing building face is permitted to be calculated for each fire compartment provided the fire separations have a fire-resistance rating not less than 45 min.
(3)In a building that is sprinklered throughout and contains an interconnected floor space, the area of the exposing building face for the interconnected floor space is permitted to be determined by considering each storey as a separate fire compartment notwithstanding openings through the floor assemblies.
OBC Div. A 1.4.1.2.(1) Limiting distance
Open OBC Div. A 1.4.1.2.(1) in the code viewerLimiting distance means the distance from an exposing building face to a property line, the centre line of a street, lane or public thoroughfare, or to an imaginary line between 2 buildings or fire compartments on the same property, measured at right angles to the exposing building face.
OBC Div. B 9.10.15.3A. Inadequate Firefighting Facilities
Open OBC Div. B 9.10.15.3A. in the code viewer(1)Where there is no fire department or where a fire department is not organized, trained and equipped to meet the needs of the community, the required limiting distance determined from Sentences 9.10.15.4.(2) and (5) and Sentence 9.10.15.5.(6), shall be doubled for a building that is not sprinklered throughout.
OBC Div. B 9.10.15.4. Glazed Openings in Exposing Building Face
Open OBC Div. B 9.10.15.4. in the code viewer(1)Except as provided in Sentences (6) to (9), the maximum area of glazed openings in an exposing building face shall
(a)conform to Table 9.10.15.4.,
(b)conform to Subsection 3.2.3. as if the glazed openings were unprotected openings, or
(c)where the limiting distance is not less than 1.2 m, be equal to or less than the limiting distance squared.
(2)Where the limits on the area of glazed openings are determined for individual portions of the exposing building face, as described in Subclause 9.10.15.2.(1)(b)(iii), the maximum aggregate area of glazed openings for any portion shall be determined using the values in Table 9.10.15.4. corresponding to
(a)the maximum total area of exposing building face, which is equal to the sum of all portions of the exposing building face, and
(b)the limiting distance of each portion. (See Note A-9.10.15.4.(2))
(3)Reserved.
(4)Reserved.
(5)Reserved
(6)The limits on the area of glazed openings shall not apply to the exposing building face of a dwelling unit facing a detached garage or accessory building, where
(a)the detached garage or accessory building serves only one dwelling unit,
(b)the detached garage or accessory building is located on the same property as that dwelling unit, and
(c)the dwelling unit served by the detached garage or accessory building is the only major occupancy on the property.
(7)The maximum aggregate area of glazed openings in an exposing building face is permitted to be up to twice the area determined in accordance with Sentence (1), where
(a)the glazed openings consist of glass blocks, as described in Article 9.10.13.7., or
(b)the building is sprinklered, provided all rooms, including closets, bathrooms and attached garages, that are adjacent to the exposing building face and that have glazed openings are sprinklered, notwithstanding any exemptions in the sprinkler standards referenced in Article 3.2.5.12.
(8)Except as provided in Sentence (9), openings in a wall having a limiting distance of less than 1.2 m shall be protected by closures, of other than wired glass or glass block, whose fire-protection rating is in conformance with the fire-resistance rating required for the wall.
(9)An opening in an exposing building face not more than 130 cm² need not be protected by a closure.
Show all 18 articles
OBC Div. B Table 9.10.15.4. Maximum Aggregate Area of Glazed Openings, % of Exposing Building Face Area
Open OBC Div. B Table 9.10.15.4. in the code viewerTable 9.10.15.4. — Maximum Aggregate Area of Glazed Openings, % of Exposing Building Face Area Forming Part of Subclause 9.10.15.2.(1)(b)(iii) and Sentences 9.10.15.4.(1) and (2) Maximum Total Area of Exposing Building Face , m² | Limiting Distance : Less than 1.2 m | Limiting Distance : 1.2 m | Limiting Distance : 1.5 m | Limiting Distance : 2 m | Limiting Distance : 2.5 m | Limiting Distance : 3 m | Limiting Distance : 4 m | Limiting Distance : 6 m | Limiting Distance : 8 m | Limiting Distance : 10 m | Limiting Distance : 12 m | Limiting Distance : 16 m | Limiting Distance : 20 m | Limiting Distance : 25 m 10 | 0 | 8 | 12 | 21 | 33 | 55 | 96 | 100 | 100 | 100 | 100 | 100 | 100 | 100 15 | 0 | 8 | 10 | 17 | 25 | 37 | 67 | 100 | 100 | 100 | 100 | 100 | 100 | 100 20 | 0 | 8 | 10 | 15 | 21 | 30 | 53 | 100 | 100 | 100 | 100 | 100 | 100 | 100 25 | 0 | 8 | 9 | 13 | 19 | 26 | 45 | 100 | 100 | 100 | 100 | 100 | 100 | 100 30 | 0 | 7 | 9 | 12 | 17 | 23 | 39 | 88 | 100 | 100 | 100 | 100 | 100 | 100 40 | 0 | 7 | 8 | 11 | 15 | 20 | 32 | 69 | 100 | 100 | 100 | 100 | 100 | 100 50 | 0 | 7 | 8 | 10 | 14 | 18 | 28 | 57 | 100 | 100 | 100 | 100 | 100 | 100 100 | 0 | 7 | 8 | 9 | 11 | 13 | 18 | 34 | 56 | 84 | 100 | 100 | 100 | 100 Over 100 | 0 | 7 | 7 | 8 | 9 | 10 | 12 | 19 | 28 | 40 | 55 | 92 | 100 | 100
OBC Div. B Table 9.10.14.4. Residential, business and personal services, and low-hazard industrial
Open OBC Div. B Table 9.10.14.4. in the code viewerTable 9.10.14.4 — Residential, business and personal services, and low-hazard industrial Forming Part of Sentence 9.10.14.4.(1) Maximum Total Area of Exposing Building Face, m² | Limiting Distance, <1.2 m | Limiting Distance, 1.2 m | Limiting Distance, 1.5 m | Limiting Distance, 2 m | Limiting Distance, 2.5 m | Limiting Distance, 3 m | Limiting Distance, 4 m | Limiting Distance, 6 m | Limiting Distance, 8 m | Limiting Distance, 10 m | Limiting Distance, 12 m | Limiting Distance, 16 m | Limiting Distance, 20 m | Limiting Distance, 25 m 10 | 0% | 8% | 12% | 21% | 33% | 55% | 96% | 100% | 100% | 100% | 100% | 100% | 100% | 100% 15 | 0% | 8% | 10% | 17% | 25% | 37% | 67% | 100% | 100% | 100% | 100% | 100% | 100% | 100% 20 | 0% | 8% | 10% | 15% | 21% | 30% | 53% | 100% | 100% | 100% | 100% | 100% | 100% | 100% 25 | 0% | 8% | 9% | 13% | 19% | 26% | 45% | 100% | 100% | 100% | 100% | 100% | 100% | 100% 30 | 0% | 7% | 9% | 12% | 17% | 23% | 39% | 88% | 100% | 100% | 100% | 100% | 100% | 100% 40 | 0% | 7% | 8% | 11% | 15% | 20% | 32% | 69% | 100% | 100% | 100% | 100% | 100% | 100% 50 | 0% | 7% | 8% | 10% | 14% | 18% | 28% | 57% | 100% | 100% | 100% | 100% | 100% | 100% 100 | 0% | 7% | 8% | 9% | 11% | 13% | 18% | 34% | 56% | 84% | 100% | 100% | 100% | 100% Over 100 | 0% | 7% | 7% | 8% | 9% | 10% | 12% | 19% | 28% | 40% | 55% | 92% | 100% | 100% Table 9.10.14.4 (continued) — Mercantile and medium-hazard industrial Maximum Total Area of Exposing Building Face, m² | Limiting Distance, <1.2 m | Limiting Distance, 1.2 m | Limiting Distance, 1.5 m | Limiting Distance, 2 m | Limiting Distance, 2.5 m | Limiting Distance, 3 m | Limiting Distance, 4 m | Limiting Distance, 6 m | Limiting Distance, 8 m | Limiting Distance, 10 m | Limiting Distance, 12 m | Limiting Distance, 16 m | Limiting Distance, 20 m | Limiting Distance, 25 m 10 | 0% | 4% | 6% | 10% | 17% | 25% | 48% | 100% | 100% | 100% | 100% | 100% | 100% | 100% 15 | 0% | 4% | 5% | 8% | 13% | 18% | 34% | 82% | 100% | 100% | 100% | 100% | 100% | 100% 20 | 0% | 4% | 5% | 7% | 11% | 15% | 27% | 63% | 100% | 100% | 100% | 100% | 100% | 100% 25 | 0% | 4% | 5% | 7% | 9% | 13% | 22% | 51% | 94% | 100% | 100% | 100% | 100% | 100% 30 | 0% | 4% | 4% | 6% | 9% | 12% | 20% | 44% | 80% | 100% | 100% | 100% | 100% | 100% 40 | 0% | 4% | 4% | 6% | 8% | 10% | 16% | 34% | 61% | 97% | 100% | 100% | 100% | 100% 50 | 0% | 4% | 4% | 5% | 7% | 9% | 14% | 29% | 50% | 79% | 100% | 100% | 100% | 100% 100 | 0% | 4% | 4% | 4% | 5% | 6% | 9% | 17% | 28% | 42% | 60% | 100% | 100% | 100% Over 100 | 0% | 4% | 4% | 4% | 4% | 5% | 6% | 10% | 14% | 20% | 27% | 46% | 70% | 100%
OBC Div. B 9.10.14.4. Openings in Exposing Building Face
Open OBC Div. B 9.10.14.4. in the code viewer(1)Except as provided in Sentences (6) to (10) and Sentence 9.10.14.6.(1), the maximum aggregate area of unprotected openings in an exposing building face shall
(a)conform to Table 9.10.14.4.,
(b)conform to Subsection 3.2.3., or
(c)where the limiting distance is not less than 1.2 m, be equal to or less than
(i)the limiting distance squared, for residential occupancies, business and personal services occupancies and low-hazard industrial occupancies, and
(ii)half the limiting distance squared, for mercantile occupancies and medium-hazard industrial occupancies.
(2)Except as provided in Sentence 9.10.14.6.(1), openings in a wall having a limiting distance of less than 1.2 m shall be protected by closures, of other than wired glass or glass block, whose fire protection rating is in conformance with the fire-resistance rating required for the wall.
(3)Reserved.
(4)Reserved.
(5)Reserved.
(6)The maximum aggregate area of unprotected openings is permitted to be up to twice the area determined according to Sentence (1), where the unprotected openings are glazed with
(a)wired glass in steel frames as described in Article 9.10.13.5., or
(b)glass blocks, as described in Article 9.10.13.7.
(7)Where the building is sprinklered, the maximum aggregate area of unprotected openings is permitted to be up to twice the area determined according to Sentence (1), provided all rooms, including closets and bathrooms, that are adjacent to the exposing building face and that have unprotected openings are sprinklered, notwithstanding any exemptions in the sprinkler standards referenced in Article 3.2.5.12.
(8)The maximum aggregate area of unprotected openings in an exposing building face of a storage garage need not comply with Sentence (1), where
(a)all storeys are constructed as open-air storeys, and
(b)the storage garage has a limiting distance of not less than 3 m.
(9)The maximum aggregate area of unprotected openings in an exposing building face of a storey that faces a street and is the same level as the street need not comply with Sentence (1) where the limiting distance is not less than 9 m.
(10)Except as provided in Sentence (11), for garages or accessory buildings that serve a single dwelling unit only and are detached from any building, the maximum aggregate area of glazed openings shall comply with the requirements for unprotected openings.
(11)The limits on the area of glazed openings need not apply to the exposing building face of a detached garage or accessory building facing a dwelling unit, where
(a)the detached garage or accessory building serves only one dwelling unit,
(b)the detached garage or accessory building is located on the same property as that dwelling unit, and
(c)the dwelling unit served by the detached garage or accessory building is the only major occupancy on the property.
OBC Div. B 9.10.15.5. Construction of Exposing Building Face of Houses
Open OBC Div. B 9.10.15.5. in the code viewer(1)Except as provided in Sentences (1.1), (2), (4) and (6), each exposing building face and any exterior wall located above an exposing building face that encloses an attic or roof space shall be constructed in conformance with Subsection 9.10.8.,
(a)for the exposing building face as a whole, or
(b)for any number of separate portions of the exposing building face.
(1.1)Sentence (1) does not apply where
(a)the limiting distance is not less than 1.2 m,
(b)the limiting distance is less than 1.2 m but not less than 0.6 m, provided that the exposing building face has a fire-resistance rating of not less than 45 min, or
(c)the limiting distance is less than 0.6 m, provided that the exposing building face has a fire-resistance rating of not less than 45 min and is clad with noncombustible material.
(2)Except as provided in Sentences (4) and (5), where the limiting distance is less than 0.6 m, the exposing building face and exterior walls located above the exposing building face that enclose an attic or roof space shall have a fire-resistance rating of not less than 45 min, and
(a)the cladding shall be metal or noncombustible cladding installed in accordance with Section 9.20., 9.27. or 9.28., (See Note A-9.10.14.5.(1)),
(b)the cladding shall
(i)conform to Subsection 9.27.12.,
(ii)be installed without furring members over gypsum sheathing at least 12.7 mm thick or over masonry,
(iii)has a flame-spread rating not more than 25 when tested in accordance with Sentence 3.1.12.1.(2), and
(iv)not exceed 2 mm in thickness exclusive of fasteners, joints and local reinforcements, or
(c)the wall assembly shall comply with Clause 3.1.5.5.(1)(b) when tested in conformance with CAN/ULC-S134, "Standard Method of Fire Test of Exterior Wall Assemblies."
(3)Reserved.
(4)The requirements for fire-resistance rating and type of cladding-sheathing assembly shall not apply to the exposing building face or projections from an exposing building face of a dwelling unit facing a detached garage or accessory building, or a garage or accessory building facing a dwelling unit, where
(a)the detached garage or accessory building serves only one dwelling unit,
(b)the detached garage or accessory building is located on the same property as that dwelling unit, and
(c)the dwelling unit served by the detached garage or accessory building is the only major occupancy on the property.
(5)Except for buildings containing 1 or 2 dwelling units only, combustible projections on the exterior of a wall that are more than 1 m above ground level and that could expose an adjacent building to fire spread shall not be permitted within
(a)1.2 m of a property line or the centre line of a public way, or
(b)2.4 m of a combustible projection on another building on the same property.
(6)Reserved.
(7)Reserved.
(8)Reserved.
(9)Reserved.
(10)Reserved.
(11)Reserved.
(12)Reserved.
(13)Heavy timber and steel columns need not conform to the requirements of Sentence (1) provided the limiting distance is not less than 3 m.
OBC Div. B Table 9.10.14.5. Minimum Construction Requirements for Exposing Building Faces — Forming Part of Sentence 9.10.14.5.(1)
Open OBC Div. B Table 9.10.14.5. in the code viewerTable 9.10.14.5 — Minimum Construction Requirements for Exposing Building Faces — Forming Part of Sentence 9.10.14.5.(1) Forming Part of Sentence 9.10.14.5.(1) Occupancy Classification of Building | Maximum Area of Unprotected Openings Permitted, % of Exposing Building Face Area | Minimum Required Fire-Resistance Rating | Type of Construction Required | Type of Cladding Required Residential, business and personal services, and low-hazard industrial | 0 - 10 | 1 h | Noncombustible | Noncombustible Residential, business and personal services, and low-hazard industrial | > 10 but ≤25 | 1 h | Combustible or noncombustible | Noncombustible Residential, business and personal services, and low-hazard industrial | > 25 but < 100 | 45 min | Combustible or noncombustible | Combustible or noncombustible Mercantile and medium-hazard industrial | 0 - 10 | 2 h | Noncombustible | Noncombustible Mercantile and medium-hazard industrial | > 10 but ≤25 | 2 h | Combustible or noncombustible | Noncombustible Mercantile and medium-hazard industrial | > 25 but < 100 | 1 h | Combustible or noncombustible | Combustible or noncombustible
OBC Div. B Table 3.2.3.7. Minimum Construction Requirements for Exposing Building Faces
Open OBC Div. B Table 3.2.3.7. in the code viewerTable 3.2.3.7 — Minimum Construction Requirements for Exposing Building Faces Forming Part of Sentences 3.1.6.9.(5) and 3.2.3.7.(1) to (4) Occupancy Classification of Building or Fire Compartment | Maximum Area of Unprotected Openings Permitted, % of Exposing Building Face Area | Minimum Required Fire-Resistance Rating | Type of Construction Required | Type of Cladding Required Group A, B, C, D, or Group F, Division 3 | 0 to 10 | 1 h | Noncombustible | Noncombustible Group A, B, C, D, or Group F, Division 3 | > 10 to 25 | 1 h | Combustible, Encapsulated Mass Timber Construction, or Noncombustible | Noncombustible Group A, B, C, D, or Group F, Division 3 | > 25 to 50 | 45 min | Combustible, Encapsulated Mass Timber Construction, or Noncombustible | Noncombustible Group A, B, C, D, or Group F, Division 3 | > 50 to < 100 | 45 min | Combustible, Encapsulated Mass Timber Construction, or Noncombustible | Combustible or Noncombustible[1][2] Group E, or Group F, Division 1 or 2 | 0 to 10 | 2 h | Noncombustible | Noncombustible Group E, or Group F, Division 1 or 2 | > 10 to 25 | 2 h | Combustible, Encapsulated Mass Timber Construction, or Noncombustible | Noncombustible Group E, or Group F, Division 1 or 2 | > 25 to 50 | 1 h | Combustible, Encapsulated Mass Timber Construction, or Noncombustible | Noncombustible Group E, or Group F, Division 1 or 2 | > 50 to < 100 | 1 h | Combustible, Encapsulated Mass Timber Construction, or Noncombustible | Combustible or Noncombustible Notes to Table 3.2.3.7.: (1) The cladding on Group C buildings within the scope of Article 3.2.2.51. and on Group D buildings within the scope of Article 3.2.2.60. shall be noncombustible or consist of a wall that satisfies the requirements of Article 3.1.4.8. (2) The cladding on buildings or parts thereof conforming to Article 3.2.2.48., 3.2.2.57. or 3.2.2.93. shall conform to Article 3.1.6.9. or be noncombustible.
OBC Div. B Table 3.2.3.1-B. Area of Unprotected Openings for Groups A, C, D, and F, Division 3 Occupancies, %
Open OBC Div. B Table 3.2.3.1-B. in the code viewerTable 3.2.3.1.-B — Area of Unprotected Openings for Groups A, C, D, and F, Division 3 Occupancies, % Forming Part of Article 3.2.3.1. Exposing Building Face, Maximum Area, m² | Ratio (L/H or H/L)[1] | Limiting Distance, 0 m | Limiting Distance, 1.2 m | Limiting Distance, 1.5 m | Limiting Distance, 2 m | Limiting Distance, 2.5 m | Limiting Distance, 3 m | Limiting Distance, 4 m | Limiting Distance, 5 m | Limiting Distance, 6 m | Limiting Distance, 7 m | Limiting Distance, 8 m | Limiting Distance, 9 m | Limiting Distance, 10 m | Limiting Distance, 11 m | Limiting Distance, 12 m | Limiting Distance, 13 m | Limiting Distance, 14 m | Limiting Distance, 16 m | Limiting Distance, 18 m | Limiting Distance, 20 m | Limiting Distance, 25 m | Limiting Distance, 30 m | Limiting Distance, 35 m | Limiting Distance, 40 m | Limiting Distance, 45 m | Limiting Distance, 50 m 10 | Less than 3:1 | 0 | 8 | 10 | 18 | 29 | 46 | 91 | 100 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A 10 | 3:1 to 10:1 | 0 | 8 | 12 | 21 | 33 | 50 | 96 | 100 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A 10 | over 10:1 | 0 | 11 | 18 | 32 | 48 | 68 | 100 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A 15 | Less than 3:1 | 0 | 7 | 9 | 14 | 22 | 33 | 63 | 100 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A 15 | 3:1 to 10:1 | 0 | 8 | 10 | 17 | 25 | 37 | 67 | 100 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A 15 | over 10:1 | 0 | 10 | 15 | 26 | 39 | 53 | 87 | 100 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A 20 | Less than 3:1 | 0 | 7 | 9 | 12 | 18 | 26 | 49 | 81 | 100 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A 20 | 3:1 to 10:1 | 0 | 8 | 10 | 15 | 21 | 30 | 53 | 85 | 100 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A 20 | over 10:1 | 0 | 9 | 14 | 23 | 33 | 45 | 72 | 100 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A 25 | Less than 3:1 | 0 | 7 | 8 | 11 | 16 | 23 | 41 | 66 | 98 | 100 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A 25 | 3:1 to 10:1 | 0 | 8 | 9 | 13 | 19 | 26 | 45 | 70 | 100 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A 25 | over 10:1 | 0 | 9 | 13 | 21 | 30 | 39 | 62 | 90 | 100 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A 30 | Less than 3:1 | 0 | 7 | 8 | 11 | 15 | 20 | 35 | 56 | 83 | 100 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A 30 | 3:1 to 10:1 | 0 | 7 | 9 | 12 | 17 | 23 | 39 | 61 | 88 | 100 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A 30 | over 10:1 | 0 | 8 | 12 | 19 | 27 | 36 | 56 | 79 | 100 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A 40 | Less than 3:1 | 0 | 7 | 8 | 10 | 13 | 17 | 28 | 44 | 64 | 89 | 100 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A 40 | 3:1 to 10:1 | 0 | 7 | 8 | 11 | 15 | 20 | 32 | 48 | 69 | 93 | 100 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A 40 | over 10:1 | 0 | 8 | 11 | 17 | 24 | 31 | 47 | 66 | 88 | 100 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A 50 | Less than 3:1 | 0 | 7 | 8 | 9 | 12 | 15 | 24 | 37 | 53 | 72 | 96 | 100 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A 50 | 3:1 to 10:1 | 0 | 7 | 8 | 10 | 14 | 18 | 28 | 41 | 57 | 77 | 100 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A 50 | over 10:1 | 0 | 8 | 10 | 15 | 21 | 28 | 41 | 57 | 76 | 97 | 100 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A 60 | Less than 3:1 | 0 | 7 | 8 | 9 | 11 | 14 | 21 | 32 | 45 | 62 | 81 | 100 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A 60 | 3:1 to 10:1 | 0 | 7 | 8 | 10 | 13 | 16 | 25 | 36 | 49 | 66 | 85 | 100 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A 60 | over 10:1 | 0 | 8 | 10 | 14 | 20 | 25 | 38 | 51 | 67 | 85 | 100 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A 80 | Less than 3:1 | 0 | 7 | 7 | 8 | 10 | 12 | 18 | 26 | 36 | 48 | 62 | 79 | 98 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A 80 | 3:1 to 10:1 | 0 | 7 | 8 | 9 | 11 | 14 | 21 | 29 | 40 | 52 | 67 | 84 | 100 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A 80 | over 10:1 | 0 | 8 | 9 | 13 | 17 | 22 | 32 | 44 | 56 | 70 | 86 | 100 | 100 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A 100 | Less than 3:1 | 0 | 7 | 7 | 8 | 9 | 11 | 16 | 22 | 30 | 40 | 51 | 65 | 80 | 97 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A 100 | 3:1 to 10:1 | 0 | 7 | 8 | 9 | 11 | 13 | 18 | 25 | 34 | 44 | 56 | 69 | 84 | 100 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A 100 | over 10:1 | 0 | 7 | 9 | 12 | 16 | 20 | 29 | 39 | 49 | 61 | 74 | 89 | 100 | 100 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A 150 | Less than 3:1 | 0 | 7 | 7 | 8 | 9 | 10 | 13 | 17 | 22 | 29 | 37 | 46 | 56 | 67 | 79 | 93 | 100 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A 150 | 3:1 to 10:1 | 0 | 7 | 7 | 8 | 10 | 11 | 15 | 20 | 26 | 33 | 41 | 50 | 60 | 71 | 84 | 97 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A 150 | over 10:1 | 0 | 7 | 8 | 11 | 13 | 17 | 24 | 31 | 39 | 48 | 57 | 68 | 79 | 91 | 100 | 100 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A 250 | Less than 3:1 | 0 | 7 | 7 | 7 | 8 | 9 | 10 | 13 | 16 | 20 | 25 | 30 | 36 | 43 | 51 | 59 | 68 | 87 | 100 | N/A | N/A | N/A | N/A | N/A | N/A | N/A 250 | 3:1 to 10:1 | 0 | 7 | 7 | 8 | 9 | 10 | 12 | 15 | 19 | 24 | 28 | 34 | 40 | 47 | 55 | 63 | 72 | 92 | 100 | N/A | N/A | N/A | N/A | N/A | N/A | N/A 250 | over 10:1 | 0 | 7 | 8 | 9 | 11 | 14 | 19 | 24 | 30 | 36 | 43 | 50 | 57 | 65 | 73 | 82 | 92 | 100 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A 350 | Less than 3:1 | 0 | 7 | 7 | 7 | 8 | 8 | 9 | 11 | 14 | 16 | 20 | 24 | 28 | 33 | 38 | 44 | 50 | 64 | 81 | 99 | N/A | N/A | N/A | N/A | N/A | N/A 350 | 3:1 to 10:1 | 0 | 7 | 7 | 8 | 9 | 9 | 11 | 13 | 16 | 19 | 23 | 27 | 32 | 37 | 42 | 48 | 55 | 69 | 85 | 100 | N/A | N/A | N/A | N/A | N/A | N/A 350 | over 10:1 | 0 | 7 | 8 | 9 | 10 | 12 | 16 | 21 | 25 | 30 | 36 | 41 | 47 | 53 | 59 | 66 | 73 | 88 | 100 | 100 | N/A | N/A | N/A | N/A | N/A | N/A 500 | Less than 3:1 | 0 | 7 | 7 | 7 | 7 | 8 | 9 | 10 | 12 | 14 | 16 | 19 | 22 | 25 | 29 | 33 | 37 | 47 | 59 | 71 | 100 | N/A | N/A | N/A | N/A | N/A 500 | 3:1 to 10:1 | 0 | 7 | 7 | 7 | 8 | 8 | 10 | 12 | 14 | 16 | 19 | 22 | 25 | 29 | 33 | 37 | 41 | 52 | 63 | 76 | 100 | N/A | N/A | N/A | N/A | N/A 500 | over 10:1 | 0 | 7 | 7 | 8 | 9 | 11 | 14 | 18 | 22 | 25 | 30 | 34 | 38 | 43 | 48 | 53 | 58 | 70 | 82 | 96 | 100 | N/A | N/A | N/A | N/A | N/A 1,000 | Less than 3:1 | 0 | 7 | 7 | 7 | 7 | 7 | 8 | 9 | 9 | 10 | 12 | 13 | 14 | 16 | 18 | 20 | 22 | 27 | 33 | 39 | 58 | 82 | 100 | N/A | N/A | N/A 1,000 | 3:1 to 10:1 | 0 | 7 | 7 | 7 | 7 | 8 | 9 | 10 | 11 | 12 | 14 | 15 | 17 | 19 | 21 | 23 | 26 | 31 | 37 | 43 | 63 | 86 | 100 | N/A | N/A | N/A 1,000 | over 10:1 | 0 | 7 | 7 | 8 | 8 | 9 | 11 | 13 | 16 | 19 | 21 | 24 | 27 | 30 | 33 | 36 | 39 | 46 | 53 | 60 | 82 | 100 | N/A | N/A | N/A | N/A 2,000 | Less than 3:1 | 0 | 7 | 7 | 7 | 7 | 7 | 7 | 8 | 8 | 9 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 17 | 20 | 23 | 33 | 44 | 58 | 74 | 93 | 100 2,000 | 3:1 to 10:1 | 0 | 7 | 7 | 7 | 7 | 7 | 8 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 20 | 23 | 27 | 37 | 49 | 63 | 79 | 97 | 100 2,000 | over 10:1 | 0 | 7 | 7 | 7 | 8 | 8 | 9 | 11 | 12 | 14 | 16 | 18 | 19 | 21 | 23 | 25 | 27 | 32 | 36 | 40 | 53 | 66 | 82 | 99 | 100 | N/A Notes to Table 3.2.3.1.-B: (1) Apply whichever is greater, L = Length of exposing building face H = Height of exposing building face
OBC Div. B Table 3.2.3.1-A. Maximum Concentrated Area of Unprotected Openings
Open OBC Div. B Table 3.2.3.1-A. in the code viewerTable 3.2.3.1.-A Maximum Concentrated Area of Unprotected Openings Forming Part of Sentence 3.2.3.1.(5) Limiting Distance, m | Maximum Area of Individual Unprotected Openings, m² 1.2 | 0.35 1.5 | 0.78 2.0 | 1.88
OBC Div. B Table 3.2.3.1-D. Area of Unprotected Opening for Groups A, B, C, D and F, Division 3 Occupancies, %
Open OBC Div. B Table 3.2.3.1-D. in the code viewerTable 3.2.3.1.-D — Area of Unprotected Opening for Groups A, B, C, D and F, Division 3 Occupancies, % Forming Part of Sentence 3.1.6.9.(5) and Article 3.2.3.1. Exposing Building Face, Maximum Area, m² | Limiting Distance, 0 m | Limiting Distance, 1.2 m | Limiting Distance, 1.5 m | Limiting Distance, 2 m | Limiting Distance, 2.5 m | Limiting Distance, 3 m | Limiting Distance, 4 m | Limiting Distance, 5 m | Limiting Distance, 6 m | Limiting Distance, 7 m | Limiting Distance, 8 m | Limiting Distance, 9 m 10 | 0 | 16 | 24 | 42 | 66 | 100 | N/A | N/A | N/A | N/A | N/A | N/A 15 | 0 | 16 | 20 | 34 | 50 | 74 | 100 | N/A | N/A | N/A | N/A | N/A 20 | 0 | 16 | 20 | 30 | 42 | 60 | 100 | N/A | N/A | N/A | N/A | N/A 25 | 0 | 16 | 18 | 26 | 38 | 52 | 90 | 100 | N/A | N/A | N/A | N/A 30 | 0 | 14 | 18 | 24 | 34 | 46 | 78 | 100 | N/A | N/A | N/A | N/A 40 | 0 | 14 | 16 | 22 | 30 | 40 | 64 | 96 | 100 | N/A | N/A | N/A 50 | 0 | 14 | 16 | 20 | 28 | 36 | 56 | 82 | 100 | N/A | N/A | N/A 60 | 0 | 14 | 16 | 20 | 26 | 32 | 50 | 72 | 98 | 100 | N/A | N/A 80 | 0 | 14 | 16 | 18 | 22 | 28 | 42 | 58 | 80 | 100 | N/A | N/A 100 | 0 | 14 | 16 | 18 | 22 | 26 | 36 | 50 | 68 | 88 | 100 | N/A 150 or more | 0 | 14 | 14 | 16 | 20 | 22 | 30 | 40 | 52 | 66 | 82 | 100
OBC Div. B 3.2.3.7. Construction of Exposing Building Face
Open OBC Div. B 3.2.3.7. in the code viewer(1)Except as provided by Sentences (3) and (4) and Articles 3.2.3.10. and 3.2.3.11., the fire-resistance rating, construction and cladding for exposing building faces of buildings or fire compartments of Group A, B, C, D or Group F, Division 3 occupancy classification shall comply with Table 3.2.3.7.
(2)Except as provided in Sentences (3) and (4) and Article 3.2.3.10., the fire-resistance rating, construction and cladding for exposing building faces of buildings or fire compartments of Group E or Group F, Division 1 or 2 occupancy classification shall comply with Table 3.2.3.7.
(3)Except as provided in Articles 3.1.4.8. and 3.1.6.9., the requirement in Table 3.2.3.7. for noncombustible cladding for buildings or fire compartments where the maximum permitted area of unprotected openings is more than 10% of the exposing building face is permitted to be waived for exterior wall assemblies that comply with Article 3.1.5.5. or 3.1.5.6.
(4)Except as provided by Articles 3.1.4.8. and 3.1.6.9., the requirement in Table 3.2.3.7. for noncombustible cladding for buildings or fire compartments where the maximum permitted area of unprotected openings is more than 25% but not more than 50% of the exposing building face is permitted to be waived where
(a)the limiting distance is greater than 5 m,
(b)the building or fire compartment and all combustible attic or roof spaces are sprinklered throughout,
(c)the cladding
(i)conforms to Subsection 9.27.6., 9.27.7., 9.27.8., 9.27.9. or 9.27.10.,
(ii)is installed without furring members, or on furring not more than 25 mm thick, over gypsum sheathing at least 12.7 mm thick or over masonry, and
(iii)after conditioning in conformance with ASTM D2898, "Standard Practice for Accelerated Weathering of Fire-Retardant-Treated Wood for Fire Testing," has a flame-spread rating not greater than 25 on the exterior face when tested in accordance with Sentence 3.1.12.1.(1),
(d)the cladding
(i)conforms to Subsection 9.27.12.,
(ii)is installed with or without furring members over gypsum sheathing at least 12.7 mm thick or over masonry,
(iii)has a flame-spread rating not greater than 25 when tested in accordance with Sentence 3.1.12.1.(2), and
(iv)does not exceed 2 mm in thickness exclusive of fasteners, joints and local reinforcements, or (See Note A-3.2.3.7.(4)(d)(iv))
(e)the exterior wall assembly complies with Article 3.1.5.5. or 3.1.5.6.
(5)The construction requirements for the exposing building face stated in Sentences (1) and (2) shall be satisfied before increasing the unprotected opening area as permitted by Sentence 3.2.3.12.(1).