Archived – Public review on proposed changes to the National Model Construction Codes – Fall 2013

National Building Code of Canada (NBC)

Division B

Part 3

Component Additive Method

The component additive method is one of the Code's recognised ways of determining the fire-resistance rating of framed assemblies. The assembly rating is calculated by adding the fire resistance times that have been attributed to various components (frame, protective membrane and additional features such as insulation or resilient channels) based on analysis of standard fire test results. The proposed changes extensively expand the current Tables in Subsection D-2.3. of Appendix D used by this method. The entries now include loadbearing and non-loadbearing applications using wood- and steel-frame construction, and new features were introduced, including the effect of resilient metal channels and floor toppings. Entries for flooring and roofing assemblies were also expanded to reflect the changes. Special care was taken to ensure that the new values introduced were based on fire tests and did not negate the established legacy assemblies.

Accessibility (Barrier Free Design)

A series of changes to accessibility provisions are proposed, which would bring the NBC more closely in line with international codes. These changes would address the diverse needs of people with disabilities (i.e. mobility and agility-related disabilities, visual, hearing or dexterity disabilities) with items such as height limits for door opening hardware; common requirements for lavatories, faucets, water closets, grab bars; increased visibility for stair nosings and handrails; and edge protection on ramps.

Part 4

Relocation of Commentary Material

It is currently not possible to design a building to Part 4 specifications unless material specified in the Part 4 User's Guide is used. This is true of design for snow load and for wind load as specified in Section 4.1. The proposed change consolidates all necessary design information into one location by transferring this material from the User's Guide into Part 4 of the NBC, where all mandatory provisions belong.

Wind Loads – Wind Tunnel Procedure

The proposed changes introduce specific provisions on how to conduct wind tunnel tests on scale models to determine wind loads. Lower limits for loads determined by the wind tunnel procedure are specified for buildings in sheltered locations and for the design of cladding and secondary structural members.

Snow Loads – Basic Roof Factor

The proposed change modifies the basic roof snow load factor to tie it to wind exposure in addition to roof size.

Snow Loads – Accumulation Factor for Multi-Level Roofs

The current Code material addresses snow accumulation on a lower roof based on snow drifting from an upper roof into the roof step (i.e. wall adjacent to the lower roof top). Two additional cases are being proposed: roof steps that face into the wind where snow drifts from the lower roof into the step, and snow drifting from the side region of the lower roof into the corner of the step.

Snow Loads – Arch Roof and Domes

The proposed changes reduce the number of load cases for arch roofs and introduce specific criteria for snow on domes.

Snow Loads – Sliding Snow

The proposed change adds specific provisions for snow that slides from an unobstructed upper roof to a lower roof. The change addresses both slippery and non-slippery upper roofs.

Snow Loads – Specific Weight

The proposed change specifies the weight of snow in drifts as a function of the ground snow load with an upper limit of 4.0 kN/m3.

Snow Loads – Ice Loading

The proposed change introduces requirements for considering ice accretion on building components and appurtenances involving small width elements attached to the building.

Live Load and Snow Load Combination

The proposed change modifies the factors in the load combination equations with live load as the principal load and snow load as the companion load, and vice versa. The change is consistent with the approach that was in place prior to the introduction of the companion action form of limit states design in the NBC 2005.

Guards – Deflection Limits

The proposed change specifies maximum limits for the lateral deflection of individual elements within a guard.

Guards – Loads

Two changes are proposed; one reduces the minimum specified live load on guards when such load is acting inward, the other clarifies that specified loading for walls acting as guards apply in an outward direction only.

Structural Design of Glass

In addition to the already referenced CAN/CGSB-12.20-M, "Structural Design of Glass for Buildings" standard, the proposed change adds the ASTM E-1300 "Standard Practice for Determining Load Resistance of Glass in Buildings" to Section 4.3. for the structural design of glass. Appropriate adjustment factors have been specified to account for the allowable stress design basis of the ASTM standard.

Earthquake Design – Low Hazard Zones

The proposed change introduces simplified seismic design requirements for buildings where the product of the importance factor, the soil factor, and the spectral acceleration at 0.2 seconds is less than 0.16, and where the product of the importance factor, the soil factor, and the spectral acceleration at 2.0 seconds is less than 0.03. As a result of these changes, all buildings will require some degree of seismic design consideration.

Earthquake Design – Seismically Isolated Structures

The proposed change introduces provisions for the design of structures with base isolation systems, termed seismically isolated structures.

Earthquake Design – Structures with Supplemental Energy Dissipation Systems

The proposed change introduces provisions for the design of structures with damping systems, termed supplemental energy dissipation systems.

Earthquake Design – Storage Racks

The NBC currently addresses seismic loads for racking storage systems that are connected to the building structure. The proposed change adds requirements for the seismic design of floor mounted steel pallet racks.

Earthquake Design – Rocking Footings

The proposed changes revise the earthquake design provisions for rocking footings to rectify an incorrect limitation on design forces and enhance them with detailed provisions including requirements to account for foundation flexibility and footing rotational stiffness.

Part 5

Other Fenestration Assemblies

Proposed changes to Section 5.10. establish minimum performance requirements as well as test procedures for curtain walls, window walls, storefronts and glazed architectural structures. The changes also provide guidance on how to properly identify these products and their applications by clarifying the code-intended meaning of common industry terms.

Wind Uplift Resistance of Membrane-Roofing Assemblies

The proposed change adds a testing requirement in Section 5.2. to evaluate dynamic wind uplift resistance of membrane-roofing systems by referencing CSA-A123.21. The change provides guidance on the applicability and limits of CSA A123.21, as well as an engineering approach to extrapolate test data for non-tested configurations.

Standards

The proposed change adds or deletes references to several standards to reflect current practice, eliminate inconsistency in application and results, provide guidance and establish clear means of compliance. Topics include material standards covering one and two component polyurethane air sealant foams products, mineral wool roof insulation board, durability in buildings, air permeance of building materials and asbestos-cement drain pipes.

Parts 3 and 9

Stairs, Ramps, Handrails and Guards

Approximately 30 proposed changes relate to stairs serving public and private spaces. The changes resolve inconsistencies between Parts 3 and 9 of the NBC, as well as inconsistencies in terminology, and increase design choices for stairs while maintaining user safety. The changes also deal with ergonomic handrail and guard requirements, and clarify the required width and height of stairs, ramps and their landings.

National Fire Code of Canada (NFC)

Division B

Part 5

Hot Works

The proposal introduces new fire watch and hot works inspection requirements to Section 5.2., as well as limitations on bitumen kettle placement and additional options for fire watch requirements. Bitumen kettles will be permitted on the roof provided a set of protection measures are implemented.

Laboratories

The proposed changes to Section 5.5. clarify the maximum quantities of dangerous goods permitted in laboratories, both in storage and in use. The changes also introduce measures to address the hazard caused by compressed gas storage, as well as new requirements for fire safety plan location when laboratories are present. Enclosure exhaust ventilation system requirements are being revised to ensure the ventilation is not shut down in a fire emergency.

NBC and NFC

Division B

Mid-Rise Combustible Construction

A CCBFC joint task group took a closer look at requirements that currently limit the height of wood buildings to no more than four storeys. Four specific areas were examined: fire protection (building elements); emergency response (fire code requirements); building and plumbing services; and structural and earthquake design. The task group determined that height and area limits for buildings constructed of combustible materials could safely be increased to six storeys by either introducing new and/or modifying various protective measures.

As a result, a series of approximately 40 changes are proposed to increase the permitted use of combustible construction up to six storeys for Group C and D major occupancies. The changes include new or revised provisions in Parts 3, 4, and 5 of the NBC dealing with fire and life safety, structural and earthquake design, and building envelope, as well as changes to Section 5.6. of the NFC dealing with the protection of buildings under construction, alteration and demolition. The proposed changes apply to residential and office-type buildings (Groups C and D occupancies, respectively, in the Codes). These can include mixed-type occupancies where lower levels may be office, residential, mercantile, assembly, low hazard or storage garage-type occupancies (Group D, C, E, A2, F2, F3 respectively), depending on whether top floors are Group C or Group D occupancy.

To address emergency responder concerns, provisions allowing greater access for firefighting are also proposed; for example, requiring that a minimum of 25% of the building perimeter be directly accessible by fire responders. Other requirements include mandatory sprinklers (conforming to NFPA-13) throughout the building; a fire-resistance rating of not less than one hour for floor and roof assemblies as well as mezzanines; and non-combustible cladding on roofs that are inaccessible to fire hoses. The building would also be occupied only once fire safety features are fully enabled. Additional changes dealing with structural and earthquake design, such as changes to seismic force resisting systems, are also proposed.

National Plumbing Code of Canada (NPC)

Divisions A and B

Water Use Efficiency

A new code sub-objective (excessive use of water) has been developed for the Environment objective to address water-use efficiency. Functional statements have been prepared as well as new mandatory technical requirements calling for water-use reduction products, components and systems in Section 2.2. relating to water-closets, urinals, faucets and showerheads. The proposal to add a water use efficiency objective to the NPC was developed after the CCBFC conducted a review of the policy case supporting such an addition.

National Energy Code for Buildings (NECB)

Division B

Part 3

Building Envelope

Prescriptive thermal requirements for building envelopes of semi-heated buildings have been developed and the rule for compliance through the performance path has been clarified. Other proposed changes to Section 3.2. introduce a performance level for air barrier assemblies of opaque building assemblies, and revise the test temperatures when testing to ASTM C1363 (hot box test) to align with those for fenestration and doors in the NECB. Determined too restrictive, the detailed trade-off path has been deleted, but the simple building envelope trade-off path remains a compliance option.

Part 4

Lighting

The proposed change updates the maximum allowable lighting power densities (LPDs) in Section 4.2. to reflect current illuminance levels recommended in the new Illuminating Engineering Society (IES) Lighting Handbook, 10th Edition and harmonizes them with ASHRAE 90.1 requirements. The interior lighting control requirements are also being updated to better reflect current technologies and standard practices and to more closely align with ASHRAE 90.1 requirements.

The proposed changes introduce a table format to improve the structure of the requirements and their understanding. The space categories in the table match those of the lighting power density requirements, thereby facilitating requirement application and enforcement.

Part 5

Heating, Ventilating and Air-Conditioning (HVAC) Systems

The proposed changes update Section 5.2. piping, duct insulation, and duct sealing requirements. Prescriptive requirements have been introduced for hydronic pump systems and heat rejection equipment. The power allowances for hydronic pump requirements are based on peak thermal demand for the space; those for heat rejection equipment are based on the equipment's rated heat rejection capacity.

Other Section 5.2. proposed changes introduce prescriptive requirements for gas-fired outdoor packaged units (rooftop units) based on standard practice and provide updates to equipment performance requirements so as to align with the performance levels in the Energy Efficiency Act regulations. The HVAC trade-off path coefficients and equations in Section 5.3. have been updated to reflect the prescriptive requirement changes.

Part 6

Service Water Heating (SWH) Systems

The proposed changes update equipment performance requirements in Section 6.2. to align with the performance levels in the Energy Efficiency Act regulations. The changes also update SWH trade-off-path coefficients and equations in Section 6.3. to reflect prescriptive requirement changes.

Part 8

Building Energy Performance Compliance Path

The proposed change introduces maximum allowable energy use intensities (EUI) for certain space uses in the performance compliance path and is based on the EUIs reflected by prescriptive path requirements. Compliance is achieved if the proposed building's EUI is less than or equal to the maximum allowable EUI. Vague or inconsistent wording, which could lead to Code interpretation issues or potential loopholes in the modeling ruleset, has been revised. Unnecessarily restrictive wording has been corrected to allow greater flexibility when modeling radiant heating/cooling systems and modeling ice-plants.

Rationale for adding a water use efficiency objective to the National Model Construction Codes

The Canadian Commission on Building and Fire Codes (CCBFC) has received a request to add, to the set of objectives contained in the National Model Construction Codes, a new objective related to water use efficiency. This request is being considered by the CCBFC in accordance with a standard protocol it has established for such purpose (see Protocol for addressing new objectives in model national codes approved at the 21^st CCBFC meeting in February 2009). At this stage of its consideration, the CCBFC is proposing that a new objective on water use efficiency be added to the National Model Construction Codes based on the following rationale:

• As per Step 1 of its protocol, requests to consider adding a water use efficiency objective have been received by the CCBFC (See letters from provinces and territories found in the minutes of the 18^th CCBFC meeting, January 2006).
• As per Step 2 of its protocol, the CCBFC has obtained preliminary comments from PTPACC (see minutes of the 19^th CCBFC meeting, February 2007) and from key stakeholders, and determined that:
  • water use efficiency is a matter within the possible mandate of model codes, and
  • there is a public policy concern that can be addressed by a new code objective on water use efficiency.
• As per Step 3 of its protocol, the CCBFC further studied this policy concern and its Canadian context, including policy goals and mix of possible instruments, and determined that a national building regulatory response is appropriate because:
  • mandating water use efficiency in new buildings and alterations of existing buildings will limit the unnecessary (or wasteful) use of water resources and thereby reduce the negative impacts (or effects) on the environment, and
  • including such an objective into the national model codes demonstrates leadership in support of the harmonization of provincial and territorial regulations, thereby contributing to regulatory and market efficiencies, and productivity in the sector.
• The CCBFC acknowledges that additional benefits which are outside the scope of the current codes would also ensue, such as:
  • reducing the need for new infrastructure, and
  • contributing to market transformation by reducing or eliminating inefficient technologies from the marketplace.

The CCBFC is now moving to subsequent steps of its protocol, which involve scoping the boundaries for a possible objective, functional statements and acceptable solutions, and consulting the public at large on these proposals, before finalizing its decision on the matter.

To receive the proposed changes for this public review, please contact Codes Canada.