Report on the Review of the Building Code: 9 Detailed recommendations for amendments to the Building Code

9.1 Building Code structure and scope

In the following section, a structure for the Building Code is proposed that:

• refines the present structure
• aligns the functional and performance requirements in the Building Code with the safety, health, wellbeing and sustainable development objectives of the Building Act
• provides a flexible framework for the future
• is broadly in line with building codes being developed under European Union directives.

The changes to the present structure are considered minor, and able to be incorporated over time.

9.1.1 Building Code structure

Internationally, building codes are structured in many different ways. A prescriptive code specifying how a building should be built could be organised around the various elements and functions of a building. Similarly, a performance-based code, which sets requirements for how buildings should perform, could be organised around the outcomes required.

The approach to describing the functional requirements and performance criteria, and developing a structure for the Building Code, was firstly to consider the outcomes required by the Act for people using buildings, and then to consider the attributes of building elements that would deliver those outcomes. For example, the requirements for a healthy indoor environment can be described by performance criteria for temperature, humidity and air quality.

The 2006 discussion document, which looked at the scope and content of a new Building Code, organised code objectives under the safety, health, wellbeing and sustainable development purposes of the Act.

The 2007 discussion document presented for consideration a structure for the Building Code that was broadly in line with building codes being developed under European Union directives.

In consultation, it was clear that many current users wanted the Building Code structured in a way that reflected their practical needs, particularly those of designers and building consent authorities. However, the diversity of views expressed on what that arrangement could be highlighted the Building Code's wide range of stakeholders and potential users.

Submissions on the 2007 discussion document expressed both support and opposition to the structure it presented. Many found the structure logical and easy to follow, while others questioned the rationale for changing the structure at all. Many of those opposed to a new structure commented that the sector was only now adjusting to the Building Code introduced in 1992, and that current changes in the sector (such as licensing of building practitioners and the accreditation of building consent authorities) would adversely affect its ability to cope with a change to the Building Code structure.

The Department considered all these views, and concluded that a wholesale change to the structure of the Building Code was neither necessary to achieve clarity and ease of use, nor desirable in terms of impact on the sector, and the cost and ease of implementation. It determined that only minor amendments to the structure of the Building Code would be needed to provide a framework for the amendments recommended.

It is recommended that the Building Code be set out as follows.

• Section 1 - General: containing the general principles for building performance, the performance framework for buildings, and requirements for maintenance and durability. This section is an expansion of Section A (General provisions) of the current Building Code.
• Section 2 - Structural performance: containing the requirements for the structural integrity, stability, means of support, and the limitation of damage and loss of amenity of buildings. This section corresponds to Section B (Stability) of the current Building Code.
• Section 3 - Fire and emergency safety: containing the requirements to safeguard people, including firefighters, and neighbouring property against fire and other related hazards, preventing the spread of fire and providing means of escape from fire and other emergencies. This section corresponds to section C (Fire Safety) of the current Building Code.
• Section 4 - Features for wellbeing and physical independence: containing requirements for the wellbeing and physical independence of people, including access, space, noise control, light and connection to the outdoors. This section is an expansion of the current section D (Access) and incorporates some of the wellbeing requirements currently in section G (Services and Facilities)
• Section 5 - Environment: containing requirements for a healthy and comfortable environment for people, including moisture, indoor air quality, indoor temperature and control of moisture from internal and external sources. This section is an expansion of the current section E (Moisture) and incorporates some of the indoor environment requirements currently in Section G (Services and Facilities).
• Section 6 - Safety of users: containing requirements for the safety of users and the risks of injury encountered by people in and around buildings. This section corresponds to the current section F (Safety of users).
• Section 7 - Sanitation: containing requirements to safeguard people from illness caused by exposure to human or domestic waste, by consumption of contaminated water, and by inadequate facilities for personal hygiene, laundering and food preparation. Sanitation requirements are in the current section G (Services and Facilities).
• Section 8 - Resource efficiency: containing requirements for the efficient use of resources for buildings including materials, energy, water and waste. The energy efficiency requirements are in the current section H.

9.1.2 Profile of weathertightness

Some submissions suggested the Building Code should have a separate section for the weathertightness of the building envelope. The awareness of weathertightness arises from high-profile problems with weathertightness, which prompted the reforms set out in the Building Act 2004. Some submitters expressed concern that weathertightness would not be adequately addressed if it did not have sufficient profile in the Building Code.

International practice in addressing weathertightness and the building envelope in performance-based codes varies. Some codes do have separate sections dealing with moisture penetration - for example, England and Wales, and the United States ICC model code.

The Building Code does not currently have a separate section for the building envelope or weathertightness, but the requirements are addressed in clauses B1 Structure, B2 Durability, E1 Surface Water and E2 External Moisture.

In the structure recommended, weathertightness and the building envelope are addressed under the 'general', 'structural performance' and 'environment' sections.

Consistent with the review's focus on outcomes, the approach taken was first to consider the outcomes for people using buildings, and then to consider the attributes of building elements that would deliver those outcomes. The outcome of a healthy indoor environment can be described by performance requirements for temperature, humidity and air quality. Achieving the performance requirements for temperature, humidity and air quality would, in most circumstances, require a weathertight building envelope which would be prescribed in Compliance Documents.

The Department concluded that the structure as recommended would provide clarity about the performance requirements to provide a healthy and safe environment for people, and that guidance about achieving a weathertight and durable building envelope would be most effectively delivered through Compliance Documents and other guidance material. The Department has released a guide to weathertightness remediation.¹¹

9.1.3 Building Code format

Section 400 of the Building Act requires the Building Code to prescribe functional requirements for buildings and the performance criteria that buildings must comply with in their intended use.

The Building Code contains an Objective statement for each clause. It is proposed that, in order to demonstrate the link between the Act and the Building Code requirements, objective statements are included to link the functional and performance requirements with the purpose of the Act.

It is recommended that the following objectives and functional requirements define the scope of the Building Code.

• Safety: An objective of this Building Code is to limit the probability that, as a result of the design, construction, use or demolition of the building, a person in or adjacent to the building will be exposed to an unacceptable risk of injury.
• Health: An objective of this Building Code is to limit the probability that, as a result of the design, construction, use or demolition of the building, a person in or adjacent to the building will be exposed to an unacceptable risk of illness.
• Wellbeing: An objective of this Building Code is to limit the probability that, as a result of the design, construction, use or demolition of the building, a person in or adjacent to the building will be exposed to an unacceptable loss of wellbeing.
• Physical independence: An objective of this Building Code is to limit the probability that, as a result of the design, construction, use or demolition of the building, a person in or adjacent to the building will be exposed to an unacceptable loss of physical independence.
• Sustainable development: An objective of this Building Code is to promote sustainable development.

Functional requirements

The objectives of this Building Code are achieved by buildings or their elements having features that:

Section 1 - General

• limit impacts from events and physical conditions to tolerable levels
• meet Building Code requirements for the intended life of the building

Section 2 - Structural performance

• maintain structural integrity, remain stable and not collapse under the effects of foreseeable events and physical conditions throughout the life of the building, including construction and demolition

Section 3 - Fire safety

• limit the risk of an accidental fire or explosion occurring
• limit the risk of fire or explosion impacting areas beyond its point of origin
• limit the risk of fire safety and other emergency systems failing to function as expected
• limit the risk of people being delayed from moving to a place of safety during a fire or other emergency
• limit the risk of firefighters or other emergency services personnel being delayed in or impeded from assisting in evacuation and performing firefighting operations
• limit the risk to firefighters or other emergency services personnel during evacuation and firefighting operations
• limit the risk of adverse effects to other property12
• limit the risk of the release of stored hazardous substances in a fire
• limit the risk of injury due to exposure to high levels of noise from alarm systems

Section 4 - Features for wellbeing and physical independence

• facilitate access to, within and from the building by all people, including people with disabilities
• facilitate access to facilities and services by all people, including people with disabilities
• facilitate connection to the outdoors
• provide space for personal activities
• limit exposure to noise originating from a source within the building
• limit exposure to noise transmitted from a source external to the building

Section 5 - Environment

• limit the risk of unwanted moisture indoors from moisture originating outside the building
• limit the risk of unwanted moisture indoors from moisture originating within the building
• limit the risk of water overflow penetrating to an adjoining property
• limit the risk of illness or loss of wellbeing caused by indoor air contaminants
• limit the risk of illness or loss of wellbeing caused by thermal conditions
• limit the risk of illness or loss of wellbeing caused by internal moisture

Section 6 - Safety of users

• limit the risk of injury due to slipping, falling, drowning or collision
• limit the risk of injury due to inadequate lighting
• limit the risk of injury due to exposure to hot surfaces and substances
• limit the risk of injury due to hazardous agents on site
• limit the risk of injury or illness due to exposure to hazardous substances

Section 7 - Sanitation

• facilitate the sanitary disposal of wastewater
• facilitate the sanitary disposal of solid waste
• facilitate the safe disposal of industrial liquid waste
• facilitate personal hygiene
• facilitate laundering
• facilitate hygienic food preparation
• facilitate cleaning in commercial and industrial buildings
• limit the risk of contamination of water supply systems
• limit the risk of consuming contaminated water
• limit the growth of legionella in heated water
• limit the risk of illness from greywater

Section 8 - Resource efficiency

• facilitate the conservation and efficient use or reuse of energy
• facilitate the conservation and efficient use or reuse of water
• facilitate the conservation and efficient use, reuse, or disposal of materials

 

---

11 External moisture - A guide to weathertightness remediation. Available from: www.dbh.govt.nz