The Current status of the Canadian Construction Codes

(1)

READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE. https://nrc-publications.canada.ca/eng/copyright

Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n’arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca.

Questions? Contact the NRC Publications Archive team at

PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. If you wish to email the authors directly, please see the first page of the publication for their contact information.

NRC Publications Archive

Archives des publications du CNRC

This publication could be one of several versions: author’s original, accepted manuscript or the publisher’s version. / La version de cette publication peut être l’une des suivantes : la version prépublication de l’auteur, la version acceptée du manuscrit ou la version de l’éditeur.

Access and use of this website and the material on it are subject to the Terms and Conditions set forth at

The Current status of the Canadian Construction Codes

Thomas, J. R.

https://publications-cnrc.canada.ca/fra/droits

L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB.

NRC Publications Record / Notice d'Archives des publications de CNRC: https://nrc-publications.canada.ca/eng/view/object/?id=50b8c36b-880c-4ad4-9e51-0937ef217df3 https://publications-cnrc.canada.ca/fra/voir/objet/?id=50b8c36b-880c-4ad4-9e51-0937ef217df3

(2)

The current status of the Canadian Construction Codes

Dr. Russell Thomas

Résumé

Presented at the Symposium on Fire Research Development & Application in the 21 Century, 2000, Taiwan

In this paper I will outline the current status of the Canadian Codes by taking a look at the development process that has taken place in Canada over the last six to ten years. In nearly all countries around the world the codes themselves are only one aspect of the complex system of regulation and control that impacts all aspects of construction. It is impossible to look at codes in isolation and many aspects of the Canadian political and governmental structure have acted to shape the structure and approach of the new Canadian Objective Based Codes System.

In Canada the authority to legislate and regulate construction has been devolved to the individual Provinces and Territories. Up until the late 1940’s, most regulation of

buildings were based upon local codes that were developed and enforced by the

individual municipalities. In most cases these were based upon older building codes that had been developed in the United kingdom. These were basically prescriptive in nature and contained little or no performance oriented provisions within them. In the late 1940’s the National Research Council of Canada’s (NRC1) Division of Building Research was asked to help in establishing a model building code that was technically based and suitable for adoption by the regulatory authorities.

Through the second half of the 20th Century the model building code continued to develop and to expand into a group of interrelated codes and supporting documents dealing with Fire, plumbing energy conservation and some specialised buildings (e.g. farm buildings). These tended to fallow along traditional prescriptive lines although, especially in the structural area, there was beginning to be a growing body of performance based requirements being established.

At the beginning of the 1990’s the Canadian Commission on Building and Fire Codes (CCBFC2), the body established by NRC to oversee the development of the model codes, undertook a public consultation process to identify what changes should be undertaken with the codes. One issue that was clearly stated was a wish to move towards a more performance based approach to codes and regulation. Other issues included the establishment of a more uniform adoption process and a more responsive codes system that could better accommodate new products, materials and approaches to building design and construction.

In 1994 the NRC Canadian Codes Center, which supports the Canadian Codes development process and the CCBFC, began, as part of the strategic plan of the CCBFC, a project to explore ways in which a new approach to building codes could be established. In setting this goal it was made clear that there should be a minimal disruption of the construction industry in any change process. The desire was to see a system that would “enable” new solutions to design and construction without disabling what was generally felt to be a “pretty good” set of codes.

1

See http://www.nrc.ca for more details of the National Research Council of Canada

2

(3)

The CCBFC had identified several fundamental attributes that building and fire codes should contain to ensure their applicability and utility in future years. These included: greater flexibility in application; improved clarity of requirements; reduced complexity; greater ease of use; reduced need for change; easier application to renovation; more responsiveness to innovation and; greater clarity of intent and consistency in scope. With these set of goals the project team began the process of researching existing models that had been established else where in the world.

In the early to mid 1990’s there was a gathering international trend to adopt what were generally referred to as “performance based codes.” As one looked in detail at these codes, it became clear that what was one persons “performance requirement” can often be said to be an other persons “prescriptive requirement.” Let me illustrate this with a relatively naive example.

Although most Canadian code writers and users have little difficulty in agreeing that a requirement that the exterior walls on the first storey of a two-storey dwelling unit be constructed of 38- by 89-mm (~ 2” by 4”) wood studs at 400-mm (~16”) centers is a “prescriptive” requirement. But what about a requirement that enclosed parking garages be ventilated at a rate of 3.9L/s·m2? Is this a “prescriptive requirement” or a “performance requirement?”

Performance requirements are generally perceived to be

requirements stated in a way that allows flexibility in the choice of solutions. As stated above, the ventilation requirement allows less flexibility than if the requirement had been to limit carbon monoxide concentration to not more than 100 ppm. On the other hand, it offers more flexibility than requiring the installation of “x” centrifugal fans with no more than “y” meters of ducting.

To someone used to prescriptive requirements, a requirement that allows freedom to choose the means of achieving a specified level of ventilation would seem like a performance requirement. In fact, once one moves even a small step away from purely prescriptive

requirements, language becomes inadequate to indicate accurately in a single phrase where on the “performance -- prescriptive spectrum” a requirement lies. This is why the terms “performance requirement” and “performance code” can cause a great deal of confusion – they can mean different things to different people.

It also soon emerged, that codes containing only performance requirements would not be achievable until a great deal of technical research and development was undertaken to establish appropriate and verifiable levels of performance. In many cases neither the science or feasible verification methods currently exist to provide a totally performance based approach. In most countries where performance-based codes have been adopted the levels at which the performance requirements have been expressed have generally been at a fairly abstract level. The adoption of a performance only approach would require the rapid development of a considerable number of verification and computational tools and models which would be necessary in order for designers and building and fire officials to apply such codes. As well, it was argued, some code

requirements do not lend themselves to a performance-based solution and are better left as prescriptive or specification-type statements.

(4)

The relationship between the degree of abstraction with which a performance

goal/objective is stated and the range of possible solution space is illustrated in Figure 1. A prescriptive requirement usually only has one or a very limited number of ways in which you can meet the requirement, in other words it limits your design choices. As one moves into performance based requirements and as those requirements become more general in nature, the number of possible options that one has in meeting those requirements becomes significantly larger.

Prescriptive Solution Range of Possible Solutions Degree of Abstraction

Figure 1. Tradeoff between degree of abstraction of statements of

objective/goal/functional-requirements and the possible range of solutions.

For example, in the UK where the structural requirements of their code is at a very high level of abstraction where generally it states that “a building shall support all the loads and forces applied to it.” Other countries have taken an approach where, again using structural requirements as the example, they have been much more specific about both the types of loads and the magnitude that they require the design to satisfy.

The next issue that had to be resolved in approaching a new code for Canada was the issue of the scope of the code. In Canada, the codes had traditionally been split into a Building Code, a Fire Code, a Plumbing Code and also an Electrical Code (which is not part of the National Model Codes but a Canadian Standard managed by one of the Standards Organizations). In general terms, the Building Code addresses buildings prior to occupation and the Fire Code deals with issues that usually come into play once the building is occupied.

The premise under which the new codes were to be developed was that this would not involve any change in the scope of the documents. This though posed a problem. For although it was generally held that the Building Code dealt with issues of Health and Safety of the occupants and also requirements relating to accessibility for the

handicapped it was also clear that over the years requirements relating to other issues seem to have been incorporated into the codes.

One of the first steps that were taken in the re-design of the Canadian codes was the initiation of a systematic investigation of the intent of every requirement within the code. This started in the mid 90’s and only when this was complete was it possible to state

(5)

clearly which issues were being addressed by each of the codes. This was not a trivial undertaking as there were some 20,000 requirements within the documents and each of these had to have the intent(s) of the requirement identified. In many cases, a

requirement had more than one intent as it may have addressed both a safety issue as well as a health issue.

By 1996 the initial view of the new code was that of a hierarchy of objectives starting with some very general objectives (Health, Safety, and Accessibility) followed by subsequent layers of more specific objectives until they reached a level of specific functional requirements that any complying building must meet. Below these functional requirements would lay a set of acceptable solutions that were based upon the existing acceptable prescriptive solutions that made up the existing codes (see figure 2).

Figure 2. Outline Building Code structure as seen in 1996

It was during this period that it was decided that it would not be appropriate to establish a purely performance based code in Canada and instead it was decided that Canada would establish a set of codes that were based upon Objectives. The rational for these Objective Based Codes grew out of the facts that it was becoming clear to those

involved in the new approach that it was not going to be possible, or even necessarily desirable, to establish measurable performance criteria for every requirement covered by a code. The existing prescriptive solutions had the merit, from industries perspective, that they could use them without having to prove that they met any specific performance criteria. For a significant component of the Canadian construction industry, what they

(6)

wanted was predictability and a simple rule book or set of solutions that thy could follow and be assured that the Authority Having Jurisdiction (AHJ) would accept them.

The use of the performance components would be used by that section of the design industry who wished to innovate and to use new and alternative design solutions. These though would have to demonstrate that their solution met the objectives established by the codes.

By the year 2000, the work of establishing the intents of each of the code requirements was completed and it became possible to more accurately identify the issues that were covered by each of the code documents.

These ended up for the Building Code as3:

• Safety

• Fire Safety

• Structural Safety

• Safety in Use

• Resistance to Unwanted Entry

• Health

• Indoor Conditions

• Sanitation

• Noise Protection

• Protection from Unacceptable Vibration or Deflection

• Containment of Hazardous Substances

• Accessibility

• Barrier-Free Path of Travel

• Barrier-Free Facilities

• Protection of Buildings

• Protection of the Building from Fire

• Protection of the Building from Structural Insufficiency

• Protection of Adjacent Buildings from Fire

• Protection of Adjacent Buildings from Structural Damage

There are also a group of other requirements that did not fall into any of the above objectives. These were single requirements within the existing code and there was no obvious rational for their continuation within the code.

The next stage of the Canadian move to Objective based Codes will begin in October 2000 with a nation wide public consultation process to gain consensus upon the list of objectives that the future code will address. Only once this process has been completed will we know which objectives the next edition of the codes will address.

As part of the consultation process, there will also be consultation on the final form of the documents themselves. At the present time the codes are seen as comprised of two

3

(7)

parts or divisions. The first component of each code, Division A, would contain the framework for the application of the code; and the second component, Division B, would contain acceptable solutions. In Division A would be found the objectives and sub-objectives of the code as well as their associated functional requirements.

Functional requirements translate objectives into operational terms. They describe the conditions to be achieved, in a general sense. There may be several functional

requirements related to any one objective. A functional requirement is:

• expressed in qualitative terms;

• a description of the outcome required, not of how to achieve that outcome;

• not intended to be used on a day-to-day basis. Functional requirements are likely to be used as part of the evaluation process, when an alternative solution or equivalent is proposed.

For example, Fire Safety has been identified as a sub-objective of the Code (see Appendix A): So, an objective of this Code is to reduce the probability that a person in or adjacent to a building will be exposed to an unacceptable fire hazard as a result of the design and construction of the building.

One functional requirement related to this sub-objective is:

Emergency Warning - Occupants shall be informed that a fire/emergency situation is occurring.

As can be seen, the functional requirement is stated in qualitative terms but is expressed in mandatory language (“occupants shall be informed”). Not all objectives,

sub-objectives, and functional requirements will apply to all buildings. For example, some structural requirements in Part 4 of the National Building Code are only applicable to post-disaster buildings. There is no intent to change this in the objective-based version. Provisions in Division A will make it clear which objectives, sub-objectives and functional requirements apply to which types of buildings.

Division A will include master lists of the objectives and functional requirements (see Appendix B). These are expected to be relatively stable and would rarely change, and therefor Division A is not expected to require updating with each new edition of the code. This Division of the code has also been designed to enable those jurisdictions having authority who wish to, to only call up Division A in their legislation. By doing so, it would allow Division B, the acceptable solutions, to be updated on a more regular basis without requiring new legislation on each occasion. Industry has often requested that the codes be more responsive to changes in technology and practices. Through this approach of separating the legislative component of the codes from the acceptable solutions it is expected that it will provide for a more responsive set of code documents.

Division B will contain all the acceptable solutions, complete with references to the applicable objectives and functional requirements (see Appendix C). Unlike Division A, it is proposed that Division B be updated on a regular basis. The majority of code users will use Division B most of the time.

An acceptable solution is essentially the current code provision with the references to the functional requirements and objectives added as shown on the right. Each

(8)

acceptable solution is deemed to contribute to achieving the objectives, sub-objectives and functional requirements listed. An acceptable solution may address more than one objective. Note that there are no objectives or functional requirements associated with application statements. Application statements are those which define the scope of application of the technical requirements of the code (i.e. the situations where the particular requirements apply).

Code users who are content to follow the requirements of the present code will see little change from the way the code is used today. They will use the left-hand column of Division B (as shown in Appendix C) and will rarely consult Division A.

However, in situations where it is not clear how to apply a code provision to a specific situation, code users will be able to refer to the objectives and functional requirements related to the provision in dispute. The objectives and functional requirements are cross-referenced in the right-hand columns of Division B. Users may also refer to detailed intent statements and appendix notes for more information about the provision.

The intent statements that were developed during the process of converting to Objective based codes will be made available as a tool to help designers and engineers

understand the reason behind each one of the acceptable solutions. It is envisioned that this will provide a valuable tool to the code user and will provide a basis for the designer and regulator to achieve a common understanding of the reason behind a specific requirement and solution in the code. Using these intent statements it will be easier for all parties to judge the merit of an alternative solution.

The proposed wording of this link between Divisions A and B in the objective-based codes is intended to make it clear that alternative solutions must perform at a level established by the acceptable solutions in the code. This is also the intent of the wording in the code’s current equivalents provisions.

So the proposed link between Divisions A and B would look like the following:

1.2.1. Compliance with the Code

1.2.1.1. Compliance with the Code

1) Compliance with this Code can only be achieved by

a) complying with the applicable acceptable solutions in Division B, or b) using alternatives to the applicable acceptable solutions in Division B

to achieve at least the minimum level of performance required by Division B in the areas defined by the objectives and functional requirements in Division A that are related to those applicable acceptable solutions.

As a result, the existing acceptable solutions will continue to act as the minimum acceptable performance level against which all future alternatives will have to be evaluated. In the fullness of time, and as our basic understanding of the underlying science becomes more firmly founded we may well begin to see the introduction of more quantifiable criteria/solutions being established within the codes. For example, there are already a number of quantified solutions offered in Division B, particularly in the area of structural design where there has long been performance based requirements.

(9)

What are the next stages? At the present time it is expected that the new Canadian Codes will be in use by the end of 2003. This will involve at least one public review process after the current public consultation. In the public review of the new codes all stakeholders will have an opportunity to comment upon the new documents and on a number of proposed technical changes in Division B. For the process of the intent analysis of the 1995 national codes brought to light a number of problem areas and changes to these have now been proposed to better address the needs of the codes.

There are a considerable number of other issues that are also being addressed during this change to objective based codes but they are too numerous to address in this paper. Suffice to say that enacting these changes to the codes documents are going to have a system wide impact. This impact will include new approaches to education and training for all of the groups involved in the construction industry as well as a developing need for tools to aid the designers, engineers and the regulatory communities.

Acknowledgements

I would like to acknowledge the help and support of my colleagues in the Canadian Codes Center without whom this work would never have reached its present stage of completion. Much of the work outlined in this paper is theirs and that of the many hundreds of volunteers who together make up the Canadian Codes System.

(10)

Appendix A

Details of the objectives and sub-objectives of the National Building Code of Canada.

• Safety

Objective: An objective of this Code is to reduce the probability that a

person in or adjacent to the building will be exposed to an unacceptable safety hazard as a result of the design and construction of the building.

• Fire Safety

Sub-objective: An objective of this Code is to reduce the

probability that a person in or adjacent to a building will be exposed to an unacceptable fire hazard as a result of the design and

construction of the building.

• Structural Safety

probability that a person in or adjacent to the building will be exposed to an unacceptable hazard due to failure of the structure as a result of the design and construction of the building.

• Safety in Use

probability that a person in or adjacent to the building will be exposed to an unacceptable risk of injury from hazards resulting from the design and construction of the building.

• Resistance to Unwanted Entry

probability that the building will have an unacceptably low level of resistance to unwanted entry as a result of the design and construction of the building.

(11)

• Health

person will be exposed to an unacceptable health hazard as a result of the design and construction of the building.

• Indoor Conditions

probability that a person in the building will be exposed to unacceptable indoor conditions as a result of the design and construction of the building.

• Sanitation

probability that, in the normal use of the building, a person in the building will be exposed to unacceptable conditions of sanitation as a result of the design and construction of the building.

• Noise Protection

probability that, in the normal use of the building, a person in the building will be exposed to unacceptably high levels of sound originating in adjacent spaces in the building.

• Protection from Unacceptable Vibration or Deflection

probability that, in the normal use of the building, a person in the building will be exposed to unacceptably high levels of vibration or deflection.

• Containment of Hazardous Substances

probability of release from a building of substances that would constitute an unacceptable hazard to public health.

• Accessibility

person with a physical or sensory limitation will be unacceptably

impeded in the access to or use of the building or its facilities as a result of the design and construction of the building.

(12)

• Barrier-Free Path of Travel

probability that a person with a physical or sensory limitation will be unacceptably impeded in the access to or circulation within a building as a result of the design and construction of the building.

• Barrier-Free Facilities

probability that a person with a physical or sensory limitation will be unacceptably impeded in the use of the facilities of a building as a result of the design and construction of the building.

• Protection of Buildings

Objective: An objective of this Code is to reduce the probability of

unacceptable loss or damage to the building or adjacent buildings resulting from specific circumstances as a result of the design and construction of the building.

• Protection of the Building from Fire

probability of unacceptable loss or damage to the building due to fire as a result of the design and construction of the building.

• Protection of the Building from Structural Insufficiency

probability of unacceptable loss of use or damage to the building due to structural failure or to lack of structural serviceability as a result of the design and construction of the building.

• Protection of Adjacent Buildings from Fire

probability of unacceptable loss or damage to adjacent buildings due to fire as a result of the design and construction of the building.

• Protection of Adjacent Buildings from Structural Damage

probability of unacceptable structural damage to adjacent buildings as a result of the construction of the building.

(13)

Appendix B

Example of a prototype of the NBC Division ‘A’ tables containing the Safety objective and sub-objectives and associated functional requirements.

T a ble 2 .2 .2 .1 .

Obje c t ive s of t he N a t iona l Building Code of Ca na da

Forming Part of Sentences 2.2.1.1.(1), 2.2.2.1.(1) and 2.3.1.1.(1)

Obje c t ive

Func t iona l

Re q’t .

(see Section 2.3.)

S Sa fe t y

An objective of this Code is to reduce the probability that a person in or adjacent to the building will be exposed to an unacceptable safety hazard as a result of the design and construction of the building.

S1 Fire Sa fe t y

An objective of this Code is to reduce the probability that a person in or adjacent to a building will be exposed to an unacceptable fire hazard as a result of the design and construction of the building, due to —

S1 .1 fire or explosion occurring R1 , R2

S1 .2 fire or explosion impacting areas beyond its point of

origin

R7 , R1 7

S1 .3 inadequate notification of a hazardous situation R5 , R7 , R1 7

S1 .4 inadequate egress facilities R1 3 , R1 4 , R1 5

S2 St ruc t ura l Sa fe t y

An objective of this Code is to reduce the probability that a person in or adjacent to the building will be exposed to an unacceptable hazard due to failure of the structure as a result of the design and construction of the building, caused by —

S2 .1 failure or excessive settlement of the supporting medium

R6 , R1 7

S2 .2 damage to the structural elements R7 , R8 , R9 , R9 , R9 , R9 ,

R1 7 R1 7R1 7 R1 7

(14)

S3 Sa fe t y in U se

An objective of this Code is to reduce the probability that a person in or adjacent to the building will be exposed to an unacceptable risk of injury from hazards resulting from the design and construction of the building, due to —

S3 .1 tripping, falling, collision or physical contact

R8 , R1 0 , R1 9

S3 .2 contact with hot surfaces or substances

R8 , R1 0 , R1 9

S3 .3 sudden exposure to hazardous substances

R8 , R1 0 , R1 9

S3 .4 inadequate notification of a hazardous situation

R8 , R1 0 , R1 9

S3 .5 inadequate egress facilities during an emergency

R1 3

T a ble 2 .3 .2 .1 .

Func t iona l Re quire m e nt s of t he N a t iona l Building Code of Ca na da

Forming Part of Sentence 2.3.2.1.(1)

Func t iona l Re quire m e nt

Subje c t

. . .

R4 A fire shall not spread beyond its point of origin. Fire

Cont a inm e nt R5 Occupants shall be informed that a fire/ emergency

situation is occurring.

Em e rge nc y Wa rning R6 The bearing medium shall be capable of supporting

the imposed loads.

Soil Be a ring Ca pa c it y R7 Materials, components, assemblies or systems

exposed to mechanisms of deterioration from foreseeable environmental conditions shall be protected or designed to prevent premature failure due to unacceptable rates of deterioration.

Dura bilit y

. . .

R1 1 Sources of contamination of potable water shall be controlled in a manner that they are not capable of

(15)

negatively affecting the health of persons.

R1 2 Reasonable facilities shall be provided for the sanitary disposal of human and domestic wastes.

Wa st e Disposa l

R1 3 The configuration of an exit facility shall permit adequate ease and rate of exiting.

Ex it

Configura t ion R1 4 Exit facilities shall be provided in sufficient number

and proximity to permit adequate ease and rate of exiting.

N um be r of Ex it s

. . .

Appendix C

An example of a section out of the proposed Division B of the NBC.

National Building Code

Division B

Ac c e pt a ble Solut ions Func t iona l

Re q’t .

(see Division A)

Obje c t ive

(see Division A)

Pa rt 3 Ac c e ss a nd U se

[NBC 1995 Part 3 non-fire safety requirements]

. . .

3 .8 .1 . Ge ne ra l 3 .8 .1 .1 . Applic a t ion

1 ) The requirements of this Section apply to all buildings except

a) houses, including semi-detached housed, duplexes, triplexes, town houses, row houses and boarding houses,

b) buildings of Group F, Division 1 major occupancy, and

c) buildings which are not intended to be occupied on a daily or full time basis, including automatic telephone exchanges, pumphouses and substations.

(16)

3 .8 .1 .3 . Ba rrie r-Fre e Pa t h of T ra ve l

1 ) Except as permitted by Subsection 3.8.3., every barrier-free path of travel shall provide an

unobstructed width of not less than 920 mm for the passage of wheelchairs.

R1 9 A1 .2 ,

S3 .1

2 ) Interior and exterior walking surfaces that are within a barrier-free path of travel shall

a) have no opening that will permit the passage of a sphere more than 13 mm in diam,

b) have any elongated openings oriented approximately perpendicular to the direction of travel,

c) be stable, firm and slip-resistant,

d) be bevelled at a maximum slope of 1 in 2, e) be provided with sloped floors or ramps

at changes in level more than 13 mm.

R1 0 R1 9

S3 .1 A1 .2 , S3 .1

3 ) A barrier-free path of travel is permitted to include ramps, elevators or other platform elevating devices where there is a difference in level.