Air quality
In addition to structural and life safety concerns, the new edition of the National Building Code of Canada also has updated requirements for indoor air quality (IAQ).
Ventilation
The 2010 NBC includes some changes to Part 6, “Heating, Ventilating, and Air-conditioning” that affect the design and operation of building ventilation systems. In previous editions of the code, it was not specifically indicated what constituted acceptable air for building ventilation purposes in terms of the concentration of particles and gases. Rather, it was simply assumed the air being vented into the indoor building environment was good enough. However, it was evident that, in some areas, outdoor air is not necessarily suitable for building ventilation.
For this reason, the new NBC has set maximum levels in air used for building ventilation purposes for particulate matter, ground-level ozone, and carbon monoxide. These are based on the National Ambient Air Quality Objective (NAAQO) benchmark levels published under Section 8, Part 1, of the Canadian Environmental Protection Act (CEPA). The goal of the limits is to reduce the probability that, as a result of the operation of a ventilation system, a person in a building will be exposed to an unacceptable risk of illness due to poor IAQ.
In locales where there are provincial or territorial requirements for air quality, the design of ventilation systems should be based on them. In the absence of such requirements, the limits prescribed by NBC apply. The change to Part 6 requires that, in areas where the outdoor air quality does not meet the acceptable NAAQO levels, building ventilation systems be provided with devices to clean the outdoor air before it is distributed to indoor occupied spaces.
Soil gas
Protection from soil gas ingress has always been required in all buildings. This protection is achieved by the mandating of a continuous air/soil gas barrier at soil/foundation interfaces. The new Health Canada guideline of 200 Bq/m3 for maximum allowable radon concentration led to further changes on specific protection from radon—one of the soil gases. Under Parts 5, “Environmental Separation,” and 6, engineers must now consider radon protection in their designs.
Air barrier requirements have been consolidated and prescriptive measures have been added to Part 9, including measures for providing a rough-in for an active radon removal system. This way, if radon becomes a problem, an economic way of removing it will be available.
The responsibility of testing for radon is left to the building owner. The Health Canada guideline recommends if test results indicate an annual average concentration exceeding 200 Bq/m3, then the completion of the subfloor depressurization system may be necessary to reduce the radon concentration. This would involve uncapping the rough-in pipe and connecting it to a ventilation system exhausting to the outside.
Photo © BigStockPhoto/Philip Schockaert
Standards
The National Model Construction Codes reference many Canadian or North American standards. One important change to the 2010 NBC is the reference in Parts 5 and 9 to a new harmonized North American Fenestration Standard for Windows, Doors, and Skylights (NAFS), along with Canadian Standards Association (CSA) A440S1-09, Canadian Supplement to AAMA/WDMA/CSA 101/I.S.2/A440.
There is now a new procedure for specifying windows, doors, and skylights, as the previous rating system has been replaced with actual design load and pressure ratings. Performance grades for windows, doors, and skylights will now need to be selected according to the Canadian Supplement to ensure products suit the conditions and geographic location for which they are intended.
A number of new ASTM standards for sealants used in building envelope construction are now referenced in Parts 5 and 9. Reflecting changes in technology, materials, and design, they replace several standards that were considerably out of date.
Climatic and seismic data
Climatic data for wind, rain, degree days, and temperature were updated using recent data from Environment Canada. (Snow load data will be updated in the 2015 code.) A better way of calculating seismic data has been used. For short-period (i.e. low-rise) structures, the seismic design loads have generally been decreased. For long-period (i.e. high-rise) structures, they have generally increased.
Secondary suites
Requirements for secondary suites (i.e. accessory apartments or in-law suites) located in houses have been introduced into Part 9. In this context, ‘houses’ include both freehold row houses and semi-detached (i.e. two dwelling units side-by-side), but excludes condominiums, duplexes (i.e. two dwelling units on top of each other), and other multi-family buildings.
Before 2010, secondary suites were addressed using the same provisions as for duplexes or multi-unit residential buildings. These provisions often imposed additional requirements in terms of fire and sound protection, egress, and exiting, when compared to requirements for single-family dwellings. The new requirements are intended to accommodate the construction of secondary suites at a reasonable cost without compromising occupant health
and safety.
Photo © BigStockPhoto/Piotr Antonów
NFC and NPC changes
The National Fire Code now requires buildings or facilities be protected from fires originating from demolition or construction sites. Protective measures might be active (e.g. sprinklers, water curtains, or fire watch) or passive (e.g. keeping the storage of combustible materials away from buildings). Requirements for fire safety plans and fire department access to sites have also been improved.
NFC has added requirements for the commissioning and decommissioning of standpipe systems, as well as restrictions on placement of bitumen kettles on rooftops. Roofing operations that include ‘hot works’—activities such as open flames or anything producing heat or sparks—must meet these new regulations.
Other key NFC changes deal with leak detection, monitoring and handling of certain dangerous goods, and the protection of storage tanks, sumps, and piping systems containing flammable and combustible liquids. Limits to quantities of flammable and combustible liquids stored within buildings have been updated.
To draw a clear line between the roles of NFC and NBC, building design requirements in the former were moved to the latter (except for spill control measures). Appropriate cross-referencing between the two codes was added.
The National Plumbing Code has updated pipe sizing requirements to accommodate the current standard practice of using water-conserving appliances and fixtures in buildings and facilities. Appendix material has been added to clarify hydraulic loading and the effect of water quality on plumbing design.
Non-potable water systems are gaining popularity due to water-conserving practices. Consequently, guidance has been introduced to indicate how these need to be designed and identified.
Conclusion
These codes are published by NRC as models for provincial and territorial building and fire regulations. However, as mentioned, they must be adopted by an AHJ to come into effect. Therefore, code-users should check with their local authority to determine what codes and regulations are in effect.
Printed versions of all three codes are available in both binder and soft-cover formats. Electronic versions come as downloadable PDF documents, replacing the CD-ROM versions. Online subscriptions are also offered.
The new codes can be purchased from NRC-IRC through the virtual store: www.nrc.gc.ca/virtualstore.
John Burrows, P.Eng., is an Ottawa-based consultant and technical writer. With an engineering background, he has been writing for the National Research Council Institute for Research in Construction (NRC-IRC) for the past 11 years.
