Construction Codes Advisory
Promoting construction of safe, healthy, habitable buildings




     Secondary Suites


Question
How does the National Building Code of Canada                Compliance with The Construction
2020 (NBC 2020) apply to secondary suites?”                  Codes Act, The Building Code
                                                             Regulations and the National Building
Answer
The NBC 2020 recognizes secondary suites as a                Code of Canada 2020 (NBC 2020) is
component that can be developed in a house. It               addressed in this advisory. Words in
details an owner’s requirements to ensure the                italics, other than Act and Regulation
secondary suite is safe, healthy and habitable.              titles, are defined in the NBC 2020.

Background
Homeowners have been developing rental spaces in their houses for generations. However, earlier
building codes did not recognize them unless all the requirements for two-unit dwellings were applied.

The NBC 2020 requires a secondary suite as a single-family dwelling component, with requirements for
life safety that are unique from earlier editions of the NBC.

Secondary Suite
A secondary suite is a self-contained dwelling unit with a prescribed maximum floor area in a building or
portion of a building of only residential occupancy. It can only contain one other dwelling unit and
common spaces. Both dwelling units must constitute a single real estate entity. Secondary suites are
typically created within an existing single-family dwelling or house, either constructed as an addition to
an existing house or incorporated within the existing buildings. A secondary suite may have more than
one storey and may be above, below or on the same storey as the principal suite.

Examples of buildings where secondary suites are allowed include individual detached houses or where
the secondary suite is in a portion of a building, semi-detached houses, free-hold row houses and
townhouses. Excluded are apartment buildings that have more than two dwelling units.

As per provincial legislation, neither the principal suite nor secondary suite can be strata-titled or
otherwise subdivided from the remainder of the house. Strata-titled means that a portion of a building
is individually owned. A residential building consisting of a principal suite and a secondary suite must be
registered under the same title and owned by a single owner.
Secondary Suites


To determine whether a secondary suite can be developed in a home, the NBC 2020 prescribes a
maximum size ratio between the principal suite and the secondary suite in Division B, Article 9.1.2.1.
This limits the floor area of all storeys to be not more than the lesser of:
    1) 80 per cent of the total floor area of all storeys of the other dwelling unit or principal suite,
         excluding the garage floor area and common spaces serving both the principal suite and the
         secondary suite; and
    2) 80 m2.

The NBC 2020 allows the relaxation of several code provisions in the design and construction of
secondary suites. The most significant is the relaxation from a fire separation to a smoke-tight barrier
between the principal suite and the secondary suite. A smoke-tight barrier is achieved by installing a
continuous layer of 12.7 mm (1/2 in.) drywall on walls and ceilings. The door leading into the secondary
suite must be solid core, minimum 45 mm (1 1/2 in.) thick and equipped with a self-closing device.

Other provisions an owner must be aware of include:
   • Bedroom windows in the principal suite and secondary suite must meet minimum
       requirements for emergency purposes.
   • The principal suite and secondary suite must have an independent heat source with no
       interconnection of heating systems.
   • Smoke and carbon monoxide alarms must be interconnected between the principal suite and
       secondary suite.

The following checklist references the NBC 2020 requirements for designing and constructing a
secondary suite.

NBC 2020, Division B, Part 9 Secondary Suite Checklist
  *NBC 2020          Design                      Design Requirements for Secondary Suite
                                                                                                           √
    Article        Description                          (or as otherwise identified)
                                    Secondary suite size limitation is 80 per cent of the total floor
                 Limits on Floor
 9.1.2.1.                           area of all storeys of the dwelling unit, with the maximum floor
                 Area
                                    area of secondary suite being 80 m2.
                                    Not less than 1.95 m and not less than 1.85 m
 9.5.3.1.        Ceiling Height
                                    under beams and ducting.
                 Doorway
 9.5.5.1.                           See Division B, Table 9.5.5.1. Size of Doors
                 Opening Sizes
                 Doorway            Not less than 1890 mm high within a secondary suite for
 9.5.5.1.
                 Openings           swing-type doors and folding doors.
                                    House with a secondary suite including common spaces
                 Entrance Door
 9.5.5.1.                           (required entrance), not less than 810 mm wide and not less
                 Sizing
                                    than 1980 mm high.
                 Stairs, Ramps,
                                    Stairs, ramps, landings, handrails and guards in garages located
                 Landings,
                                    in a house with a secondary suite, including their common
 9.8.1.2.        Handrails and
                                    spaces, shall comply with the requirements of Section 9.8 as
                 Guards in
                                    applicable to dwelling units.
                 Garages
 9.8.2.1.        Stairway Width     Not less than 860 mm.




                                                                                                           2
Secondary Suites

           Clear Height
9.8.2.2.                     Not less than 1950 mm.
           Over Stairs
                             The following are permitted in a house with a secondary suite:
                             • Straight flights,
                             • Curved flights (see Division B, Part 3),
           Permitted Stair   • Spiral stairs (see Division B, Sentence 9.8.4.7.(2)), flights with
9.8.3.1.
           Configurations      rectangular treads and winders (see Division B, Article 9.8.4.6.)
                               or
                             • Flights with a mix of rectangular and tapered treads where all
                               tapered treads shall turn in the same direction.
           Dimension for     Rectangular treads, tapered treads and winders:
9.8.4.1.
           Stair Risers      • Maximum rise of 200 mm and minimum rise of 125 mm.
           Dimension for
                             Rectangular treads:
9.8.4.2.   Rectangular
                             • Maximum run of 355 mm and minimum run of 255 mm.
           Treads
9.8.4.9.   Open Risers       Permitted in interior and exterior stairs.
9.8.5.2.   Ramp Width        Not less than 860 mm.
           Height Over
9.8.5.3.                     Not less than 1950 mm.
           Ramp
                             Landing may be omitted at the top on an exterior flight of stairs
                             serving a house with a secondary suite provided:
                             • the stair does not contain more than three risers,
           Required
9.8.6.2.                     • the principal door is a sliding door or swings away from the
           Landings
                               stairs, and
                             • only a storm or screen door, if any, swings over the stairs and
                               is equipped with hardware to hold it open.
           Height Over
9.8.6.4.                     Not less than 1950 mm.
           Landings
           Required
                             One handrail is required on all interior stair configurations
9.8.7.1.   Handrails-
                             regardless of stair width.
           Interior Stairs
           Required          One handrail is required on straight or curved ramps less than
9.8.7.1.   Handrails –       1100 mm in width and two handrails are required on all ramps
           Ramps             1100 mm or greater in width.
           Required
                             One handrail is required on all exterior stair configurations
9.8.7.1.   Handrails –
                             having more than three risers.
           Exterior Stairs
           Continuity of     The handrail can start from a newel post or volute installed on
9.8.7.2.
           Handrails         the bottom tread.
                             Applicable where exterior or interior handrails are attached to
                             wood studs or blocking, the attachment shall be deemed to
           Design and        comply where:
9.8.7.7.   Attachment of     • the attachment points are spaced not more than 1.2 m apart,
           Handrails           measured on the horizontal plane,
                             • the first attachment point at either end is located no more
                               than 300 mm from the end of the handrail, and




                                                                                                    3
Secondary Suites

                              • the fasteners consist of not less than 2 No. 8 wood screws at
                                each point, penetrating not less than 32 mm into solid wood.
                              Division B, Table 9.8.8.2. prescribes loads on guards but need
            Loads on
9.8.8.2.                      not apply where the guard construction used has been
            Guards
                              demonstrated to provide effective performance.
                              Interior guard height not less than 900 mm high and exterior
            Height of         guard height not less than 900 mm high where the walking
9.8.8.3.
            Guards            surface served by the guard is not more than 1800 mm above
                              the finished ground level.
            Loads –
9.8.9.1.                      Not less than 1.9 kPa.
            Stairs/Ramps
                              Spacing between stringers to be not less than 900 mm on centre
            Stair Stringer
9.8.9.4.                      or 1200 mm on centre where the risers support the front portion
            Spacing
                              of the tread.
            Fire Separation   Constructed as a smoke-tight barrier of not less than 12.7 mm
9.9.4.2.
            for Exits         gypsum board.
                              Unprotected openings in exterior walls shall be protected with
                              wired glass in fixed steel frames or glass block conforming to
                              Articles 9.10.13.5. and 9.10.13.7. where an unenclosed exterior
            Openings Near
                              exit stair or ramp provides the only means of egress from a suite
            Unenclosed
                              and is exposed to fire from unprotected openings in the exterior
9.9.4.4.    Exterior Exit
                              walls of another fire compartment, or another dwelling unit,
            Stairs and
                              ancillary space or common space in a house with a secondary
            Ramps
                              suite, and unprotected openings in the exterior walls of the
                              building are within 3 m horizontally and less than 10 m below or
                              less than 5 m above the exit stair or ramp.
                              Unprotected openings shall be protected with wired glass in
                              fixed steel frames or glass block conforming to Articles 9.10.13.5.
                              and 9.10.13.7., where an exterior exit in one dwelling unit,
                              ancillary space or common space in a house with secondary suite
            Openings Near     is within 3 m horizontally of the unprotected opening serving
9.9.4.6.
            Exit Doors        another dwelling unit, ancillary space or common space in a
                              house with secondary suite and the exterior walls of the fire
                              compartments, dwelling units, ancillary spaces and common
                              spaced in a house with a secondary suite intersect at an exterior
                              angle of less than 135o.
                              The upper suite shall be provided with a second and separate
                              means of egress where an egress door from that dwelling unit
            Shared Egress     opens onto an exterior passageway that has a floor assembly
9.9.9.3.
            Facilities        with a fire-resistance rating less than 45 min, is served by a
                              single exit stairway or ramp, and is located more than 1.5 m
                              above adjacent ground level.
                              Window designed for emergency purposes, including a minimum
                              unobstructed opening of not less than 0.35 m2 in area with no
            Egress from
9.9.10.1.                     dimension less than 380 mm and designed to maintain the
            Bedroom
                              required opening during an emergency without the need for
                              additional support.




                                                                                                    4
Secondary Suites

             Wall, Columns,
             Aches, and        Constructed with not less than 12.7 mm gypsum board as
9.10.8.3.
             Beam              protection.
             Protection
                               This Article identifies the application of Division B, Subsection
                               9.10.9. Fire Separations and Smoke-tight Barriers between
9.10.9.1.    Application       Rooms and Spaces within Buildings, with specific reference to
                               smoke-tight barriers required in houses with a secondary suite
                               and common spaces.
             Construction of
9.10.9.2.                      Constructed as a smoke-tight barrier.
             Wall or Floors
             Protection of
9.10.9.3.                      Solid core door, 45 mm thick with a self-closing device.
             Openings
             Floor             Floor assemblies within a house with a secondary suite need not
9.10.9.4.
             Assemblies        be constructed as fire separations.
                               Walls and floor-ceiling framing in a house with a secondary suite
                               that separate dwelling units from each other or dwelling units
             Separation of     from ancillary spaces and common spaces are not required to
9.10.9.16.   Residential       have a fire-resistance rating where the walls and floor-ceiling
             Suites            framing are protected by a continuous smoke-tight barrier of not
                               less than 12.7 mm thick gypsum board installed on both sides of
                               walls and the underside of floor-ceiling framing.
                               Where a public corridor is located in a house with a secondary
                               suite, a continuous smoke-tight barrier of not less than 12.7 mm
             Separation of
                               gypsum board shall be installed on both sides of walls separating
9.10.9.17.   Public
                               the corridor from the remainder of the building and the
             Corridors
                               underside of floor-ceiling framing separating the corridor from
                               the remainder of the building.
                               Both sides of any wall assembly and the underside of any floor-
                               ceiling framing separating the furnace room from both dwelling
9.10.10.4.   Furnace Room
                               units or their common spaces are protected with a smoke-tight
                               barrier of not less than 12.7 mm gypsum board.
                               A party wall on a property line of a building of residential
                               occupancy need not be constructed as a firewall, provided it is
             Firewalls Not     constructed as a fire separation having not less than a 1 h fire-
9.10.11.2.
             Required          resistance rating, where the party wall separates a house with a
                               secondary suite including their common spaces, or two houses
                               with as secondary suite including their common spaces.
                               Prescribes protection requirements where interior walls
                               between dwelling units, ancillary spaces or common spaces in a
             Exterior Walls
                               house with a secondary suite are not constructed as fire
9.10.12.3.   Meeting at an
                               separations, the exterior wall of each dwelling unit, ancillary
             Angle
                               space or common space within 1.2 m distance shall be finished
                               on the interior with not less than 12.7 mm gypsum board.
                               Prescribes required soffit protection where the portion of any
             Protection of     soffit enclosing a projection is:
9.10.12.4.
             Soffits           • less than 2.5 m vertically above a window or door; and
                               • less than 1.2 m from either side of the window or door.



                                                                                                   5
Secondary Suites
              Application of     Applicable to spatial separation requirements when constructing
 9.10.15.1.
              the NBC            a dwelling unit which contains a secondary suite.
                                 Wirelessly interconnected or hard-wired connected between the
 9.10.19.5.   Smoke Alarms
                                 principal suite and the secondary suite.
              Sound              Apparent Sound Transmission Class (ASTC) rating of not less than
 9.11.1.1.
              Transmission       47 or, Sound Transmission Class (STC) rating of not less than 50.
                                 No requirement for heating-season ventilation for exits, public
              Required           corridors and ancillary spaces that are not within a dwelling unit
 9.32.1.2.
              Ventilation        unless the ancillary spaces contain exhaust devices where make-
                                 up air is required.
                                 This Article applies to ancillary spaces that contain an exhaust
              Protection         device, where the space is not within a dwelling unit in a house
              Against            with a secondary suite and where the house with a secondary
 9.32.3.8.
              Depressurization   suite contains a fuel-fired space-heating appliance or fuel-fired
                                 water-heating appliance or other than direct-vented or
                                 mechanically vented types.
              Carbon Monoxide
                                 Interconnected with all CO detectors in principal suite and
 9.32.3.9.    Alarms
                                 secondary suite and common spaces.
              Heating and Air    Designed as per Section 9.33. and principal suite and secondary
 9.33.1.1.
              Conditioning       suite each with a separate source of heating and cooling.
 9.33.1.1.    Ducting            No interconnection between principal suite and secondary suite.
                                 22oC in living spaces, 18oC in ancillary spaces, 18oC in common
              Indoor Design
 9.33.3.1.                       service rooms, ancillary spaces and exits in houses with a
              Temperature
                                 secondary suite; and 15oC in heated crawl spaces.
                                 Applies where a single heating systems serves a house with a
              Heating System
 9.33.4.3.                       secondary suite and requires individual controls to be provided
              Control
                                 in each dwelling served by the system.
                                 Three-way switches located at the head and foot of every
 9.34.2.3.    Stairways          stairway shall be provided to control at least one lighting outlet
                                 with fixture for stairways with four or more risers.
                                 The application of energy efficiency to houses with or without a
              Compliance and
 9.36.1.3.                       secondary suite would be with Subsection 9.36.5. and 9.36.7.
              Application
                                 forming part of Section 9.36. Energy Efficiency.

*The National Building Code of Canada, the National Energy Code of Canada for Buildings, the National
Plumbing Code of Canada and the National Fire Code of Canada are available for download in a digital
format, free of charge from Codes Canada.




                                                                                                        6
Secondary Suites

Saskatchewan Secondary Suite Incentive Grant Program
For information on the Government of Saskatchewan Secondary Suite Incentive Grant Program (SSI)
please contact the Ministry of Finance:

Ministry of Finance                                                            Toll-Free 1-800-667-6102
Revenue Division                                                               Regina 306-787-6645
PO Box 200 REGINA SK S4P 2Z6                                                   ssisask@gov.sk.ca
Toll Free 1-800-667-6102
Regina 306-787-6645




 Building and Technical Standards Branch                                           Construction Standards Advisory
 Government of Saskatchewan                                                                Secondary Suites
 Ministry of Government Relations                                                            January 2024
 1430 - 1855 Victoria Avenue
 Regina, Saskatchewan S4P 3T2
 (306) 787-4113 Phone
 btstandards@gov.sk.ca                                                             Original approved and signed by:
 www.saskatchewan.ca/btstandards                                                      Chief Codes Administrator
 The Saskatchewan Ministry of Government Relations publishes this advisory to provide users with information on the topic
 contained herein. In case of conflict between The Construction Codes Act (the CC Act), The Building Code Regulations (the BC
 Regulations) and the National Building Code of Canada 2020 (NBC 2020) and this advisory, provisions of the CC Act and NBC
 2020 shall apply.




                                                                                                                                7
