Australian Building Surveyors and Inspectors Key Glossary Terms

This page serves as a comprehensive glossary of terms relevant to building surveyors and inspectors in Australia. Understanding these terms is crucial for professionals navigating the complexities of building codes, regulations, and construction practices. Below, you'll find definitions for a range of key terms that frequently appear in the context of building surveying and inspection.

Above Ground Rainwater Tank

A rainwater storage unit that is entirely situated above the surface of the ground, not embedded or buried in any way.


Designed or modified to ensure usability by individuals with disabilities, incorporating features that facilitate ease of use and access.


A path that is consistently accessible, as defined in AS 1428.1, leading to, into, or within a structure, enabling seamless movement for all users.

Accredited Testing Laboratory

Organisations recognised for their capability to conduct specific tests, including:

  • Entities accredited by the National Association of Testing Authorities, Australia (NATA).
  • International organisations accredited by bodies recognised by NATA through mutual recognition agreements.
  • Organisations deemed accredited testing laboratories under applicable legislation at the time of testing.

Activity Support Level

The extent to which a space facilitates occupants in carrying out various activities, taking into account both the nature of the activities and the characteristics of the occupants.

Activity Traits

Characteristics of activities that are anticipated to take place within a space, influencing its design and functionality. This includes considerations for actions like sleeping, resting, leisure activities, and dressing, which dictate spatial and ergonomic requirements.

Administering Body

The organisation responsible for overseeing the WaterMark Certification Scheme, ensuring compliance and standardisation across water-related products and systems.

Aged Care Building

A Class 9c building designated for the accommodation of elderly individuals who require personal care services and assistance, especially in emergency evacuation scenarios.


Activities related to farming and animal husbandry, excluding viticulture and forestry, such as cropping, grazing, horticulture, and aquaculture.


A passageway located at the end of seating rows, leading to a cross-over or an exit, facilitating movement within venues like theatres and auditoriums.


A system designed to actively regulate the temperature within a space through cooling or heating, excluding systems for cold or hot rooms or those maintaining conditions for specialised equipment or processes.

Alarm Zone

A designated area within a building equipped with one or more smoke alarms connected to a singular alarm circuit, as per Specification 23.

Alpine Area

Regions likely to experience significant snowfalls, defined by altitude above the Australian Height Datum (AHD) in New South Wales, the ACT, Victoria, and Tasmania. These areas are subject to specific construction considerations due to their unique environmental conditions.


Any modification made to a building, including extensions or additions, impacting its structure, layout, or functionality.

Aluminium Composite Panel (ACP)

A construction material consisting of aluminium sheets bonded to various core materials, used in façade systems and architectural cladding.


Features of a building or environment that contribute to the comfort, health, and well-being of its occupants or users.

Ancillary Element

A secondary component that is not integral but is attached to a primary structural or architectural element.

Annual Exceedance Probability

The likelihood of a specific rainfall total being surpassed within any given year, used in flood risk assessment and management.

Annual Greenhouse Gas Emissions

The total amount of greenhouse gases emitted by a building's services over a year, calculated theoretically and excluding emissions from certain sources like kitchen exhausts.

Appropriate Authority

The designated authority responsible for determining compliance with Performance Requirements, typically a building surveyor or certifier.

Approved Disposal System

A sewage, sullage, or stormwater disposal system that has been approved by the relevant jurisdictional authority.

Articulated Masonry

Masonry construction that incorporates measures to accommodate movement, ensuring structural integrity and reducing the risk of cracking.

Assembly Building

A structure designed to host gatherings for various purposes, including civic, educational, entertainment, and transit purposes, each with specific design and safety considerations.

Assessment Method

Techniques or processes used to ascertain whether a Performance Solution or Deemed-to-Satisfy Solution meets the established Performance Requirements.

Assumed Cooling Thermostat Set Point

A parameter used in calculating cooling degree hours, based on the mean January outdoor air temperature, crucial for energy efficiency and thermal comfort assessments.


A vertical space within a building, connecting multiple storeys and enclosed at the top, which may include adjacent areas not separated by fire barriers.

Atrium Well

The portion of an atrium defined by the perimeter of floor openings or the combination of floor perimeters and external walls.


A section within an entertainment venue designed to accommodate audiences


Backflow Prevention Device

A mechanism designed to prevent the unintended reversal of flow of water or contaminants into the water service or a Network Utility Operator’s water supply. This includes air gaps, break tanks, or mechanical devices.


The condition where the pressure in the downstream side of a water service becomes greater than the supply pressure, leading to a reversal of water flow.


A reversal of water flow caused by a negative pressure within the distribution pipes of a water service or supply, potentially drawing contaminants back into the clean water supply.


An area in a Class 9b building associated with a stage, used for the storage of scenery, props, equipment, dressing rooms, and similar purposes.

Battery System

A configuration of one or more chemical cells connected in series, parallel, or a combination of both, for the purpose of storing electrical energy.


Any obstruction within a water service, sanitary plumbing, or drainage system that impedes normal flow.


A vessel or arrangement of vessels and parts where steam or vapour is generated, or water is heated under pressure above atmospheric levels by various means. This includes components like superheaters, piping, and controls, but excludes systems heated below the liquid’s normal boiling point.

Bond Breaker

A component of a waterproofing system that prevents the membrane from adhering to the substrate, ensuring flexibility and preventing damage from movement.

Breaking Surf

An area where sea waves break regularly, at least four days a week, but not including white caps or choppy conditions. This typically occurs in open sea exposures and not in sheltered areas.

Building Complexity Criteria

Criteria used to assess the complexity level of a building or a part thereof, considering factors like effective height, use of Performance Solutions for structural and fire safety, location in disaster-prone areas, and other specific attributes.

Buried Rainwater Tank

A rainwater collection tank that is fully embedded underground, covered entirely by earth.


The phase of a fire including growth, full development, and decay without intervention, after which the fire no longer threatens the structural integrity or fire separation functions of a building.

Brush Fence

A fence made primarily of Broombrush (Melaleuca Uncinata), typically used for privacy and aesthetic purposes.

Bulk Grain Storage Facility

A commercial facility for the bulk storage or handling of granular materials like grain or ore. This includes structures like silos and sheds designed to accommodate minimal occupancy.



A designated building used for parking motor vehicles, excluding private garages and facilities offering vehicle servicing beyond basic cleaning or polishing.


A void found between two leaves of masonry or between the leaf of a masonry veneer and its supporting frame, aiding in moisture management and insulation.

Cavity Wall

A wall construction featuring a drained cavity within, for purposes of moisture control and thermal insulation, as specified in building regulations.

Cell Type Silo

A specific type of bulk grain storage facility characterised by its cell-like storage compartments, facilitating the segregation and management of different materials.

Centre-based Care Class 4 Facility

Defined by Centre Based Care Class 4 Standards, specifying requirements for certain types of childcare or educational facilities.

Centre-based Care Class 5 Facility

Defined by Centre Based Care Class 5 Standards, outlining the criteria for the establishment and operation of specific childcare or educational services.

Certificate of Accreditation

Issued by a state or territory accreditation authority, certifying that a building material, construction method, or design meets the specific requirements of the National Construction Code (NCC).

Certificate of Conformity

Granted under the Australian Building Codes Board scheme for product and system certification, affirming that a building material, method of construction, or design complies with the NCC standards.

Certification Body

An entity accredited by the Joint Accreditation System of Australia and New Zealand (JAS-ANZ) to certify materials, products, constructions forms, or designs, excluding those accredited solely under the CodeMark Australia Certification Scheme or WaterMark Certification Scheme.


Data used in access solution modelling to depict how occupants interact with a building, including movement speeds, turning ability, reach capability, perception of luminance contrast, and hearing threshold.

Children’s Service

As defined under the Children's Services Act 1996, referring to services providing education and care primarily to children, excluding those mainly for school-aged children.

Clad Frame

Construction involving a timber or metal frame with external cladding resistant to minor movements, and may include substructure masonry walls up to 1.5 metres in height.

Climate Zone

A classification of areas with similar climatic characteristics for the purpose of applying energy efficiency provisions, as defined in national standards and guidelines.


Refers to materials or construction parts made wholly or partially from combustible materials, as determined by specific testing standards.

Combustible Cladding Product

Specifically refers to aluminium


Daily Outdoor Temperature Range

The variation between the highest and lowest temperatures experienced in a single day.

Damp-proof Course (DPC)

A barrier made of an impervious material installed in walls or piers to prevent moisture from rising or falling through the masonry.

Deemed-to-Satisfy Provisions

Standards and specifications identified within the building codes that, when adhered to, are automatically recognized as meeting the Performance Requirements.

Deemed-to-Satisfy Solution

A construction or design approach that complies with the Deemed-to-Satisfy Provisions of the building codes.

Defined Flood Event (DFE)

A flood occurrence defined by the appropriate authority for managing flood risks in a specific area, used as a benchmark in development planning.

Defined Flood Level (DFL)

The water level associated with the Defined Flood Event, measured relative to a specific datum point.

Dehumidification Gram Hours

The measure of humidity removal over an hour when the mean humidity exceeds 15.7g/kg, calculated as the difference between the mean outdoor humidity and 15.7g/kg.

Designated Bushfire Prone Area

Areas legally identified under legislation as being at risk of or likely to be affected by bushfires.

Design Bushfire

A detailed description of a bushfire's potential behavior based on local weather conditions, topography, and fuel loads, used in planning and construction to mitigate fire risk.

Design Fire

A theoretical representation of a fire within a specific design scenario, used for fire safety engineering analysis.

Design Scenario

A detailed outline of events for which fire safety engineering analysis is conducted, including all conditions and variables considered.

Design Wind Speed

The peak gust wind speed used for structural design purposes, determined according to relevant standards such as AS/NZS 1170.2 or AS 4055.

Detention Centre

A facility designed for the secure detention of individuals, such as prisons, remand centres, juvenile detention centres, or psychiatric detention facilities.

Development Consent

Legal permission granted under the Environmental Planning and Assessment Act 1979 for specific developments or land uses.

Direct Fix Cladding Wall

A wall construction where cladding is attached directly onto the framing without a drained cavity, as specified in building codes.

Discontinuous Construction

Construction featuring a minimum 20mm cavity between two separate leaves, with specific requirements for masonry and non-masonry walls to ensure there's no direct mechanical linkage between the leaves.

Display Glazing

Windows or glass panels used in retail settings to showcase merchandise, situated adjacent to walkways, excluding those used in food service environments.

Domestic Services

Essential engineering systems within a building that manage or control energy use, including heating, ventilation, air conditioning, and on-site renewable energy systems, but not including cooking facilities or portable devices.


Systems designed for the removal of waste water (sanitary or trade waste) or stormwater from a building and its premises.

Drainage Flange

A component attached to a waste pipe to prevent leaks where the pipe penetrates a floor, allowing for proper drainage.

Drainage Riser

A vertical waste pipe connecting floor waste to the broader drainage system.

Drinking Water

Water that is primarily intended for human consumption, alongside other domestic uses, with quality guidelines provided by the National Health and Medical Research Council.


Early Childhood Centre

Facilities providing education and care services to young children, as defined under the Education and Care Services National Law and respective state or territory regulations, excluding services primarily for school-aged children in after-school settings.

Effective Height

The vertical distance from the floor of the lowest storey considered in calculating the building's rise in storeys to the floor of the highest occupied storey.


The effectiveness of a system or solution in achieving specified design objectives under relevant fire scenarios, based on its performance according to system specifications.

Electricity Network Substation

A facility where high voltage electrical supply is transformed or converted, controlled by a licensed network service provider.

Electric Passenger Lift

A lift operated by an electric motor for transporting people between floors within a building.

Electrohydraulic Passenger Lift

A lift where movement is powered by liquid under pressure acting on a piston, with the pressure generated by an electric motor-driven pump.

Energy Value

The overall cost of energy use to society, including impacts on building users, the environment, and energy networks.

Engaged Pier

A structural element bonded to a masonry wall either by direct integration of masonry units or through the use of ties, providing additional support.

Entertainment Venue

Facilities defined under local regulations as spaces designed for the purpose of hosting entertainment events.


In building terms, refers to the parts of a building's structure that separate conditioned or habitable spaces from the outside or from unconditioned spaces, including walls, roofs, and floors.


Referring to a level of health, safety, and amenity that is comparable to what is achieved  

Evacuation Route

A designated pathway for safe exit from any part of a building, including sole-occupancy units in Class 2, Class 3, or Class 4 parts, leading to a safe location. This encompasses exits, public corridors, and similar pathways.

Evacuation Time

The duration from the initiation of an emergency to the moment all occupants are expected to have safely evacuated a building.


Refers to any path or opening designed to provide a means of egress from inside to an outdoor space or road, including:

  • Internal or external stairways.
  • Ramps.
  • Fire-isolated passageways.
  • Doorways leading directly outside or to open space. It may also refer to a horizontal exit or a fire-isolated passageway leading to such an exit.

Expert Judgement

The assessment made by a qualified expert on whether a Performance Solution or Deemed-to-Satisfy Solution meets the Performance Requirements. This requires contemporary, relevant qualifications and experience, the extent of which may vary based on the complexity of the proposal and regulatory requirements.

External Wall

In Volume One, any outer wall of a building that is not a common wall. In Volume Two, it refers to an outer wall that is not a separating wall between buildings.

Extra-Low Voltage

Electrical systems or circuits operating at a maximum of 50 V AC or 120 V ripple-free DC, considered safe from electric shock risks.



The essential structural components of a building, including its roof, ceilings, walls, glazing, and floors.

Farm Building

A Class 7 or 8 structure located on agricultural land used for farming purposes, such as storage or operational needs related to farming, with occupancy restrictions based on floor area and a total floor area limit.


Activities involved in the cultivation, propagation, and harvesting of plants, fungi, or their products, and the maintenance of animals for breeding, sale, or their produce, excluding forestry and recreational animal activities.

Farm Shed

A specific type of farm building primarily used for storage or farming-related activities, characterized by limited occupancy and larger floor area restrictions than typical farm buildings.

Farm Vehicle

Vehicles specifically used for agricultural purposes, assisting in various farming operations.


Refers to cinematographic films of 35 mm size or larger, used in traditional film projection.

Finished Ground Level

The final level of the ground adjacent to a building's foundation after construction and landscaping are completed.

Fire Actions

Specific fire-related phenomena a building may be exposed to during a bushfire, including airborne embers, burning debris, heat transfer from combustible materials, radiant heat, and flame contact from the fire front, as well as post-fire effects.

Fire Brigade

An official organization established by law with responsibilities including fire suppression, emergency response, and public safety.

Fire Brigade Station

A facility operated by a state or territory government housing a fire brigade unit, equipped for emergency response and fire fighting.

Fire Compartment

A section of a building separated by fire-resistant barriers to contain the spread of fire, with specific requirements for walls, floors, and protected openings to maintain fire resistance levels.

Fire Growth

Describes the phase of a fire where heat release rate and temperature increase, contributing to the fire's development and potential spread.

Fire Hazard

The risk or potential danger posed by the ignition and spread of fire, including the production of smoke and gases, and the exposure to these hazards.

Fire Hazard Properties

Attributes of materials or assemblies that describe their behavior under fire conditions, including average specific extinction area, critical radiant flux, Flammability Index, Smoke-Developed Index, and Group Number, as determined by specific testing and standards.

Fire Intensity

The measurement of energy release from a fire, expressed in watts, which can be calculated based on empirical data or theoretical models.

Fire-isolated Passageway

A fire-resistant corridor or hallway that provides a safe egress route to or from fire-isolated stairways, ramps, or directly to the exterior or open space of a building.

Fire-isolated Ramp

A ramp enclosed within a fire-resistant structure, designed to facilitate egress from different levels of a building during a fire emergency.

Fire-isolated Stairway

A stairwell enclosed within a fire-resistant shaft, including its enclosing floors and roof, intended to provide a safe egress route during a fire.

Fire Load

The total potential energy content of all combustible materials within a fire compartment, including furniture, finishes, and other contents, expressed in terms of their calorific value.

Fire-protected Timber

Timber building elements that comply with Specification 10, offering resistance to fire through specific treatments or construction methods.

Fire-protective Covering

Materials used to enhance fire resistance, including:

  • 13 mm fire-protective grade plasterboard.
  • 12 mm cellulose cement flat sheeting that meets AS/NZS 2908.2 or ISO 8336 standards.
  • 12 mm fibrous plaster reinforced with a 13 mm x 13 mm x 0.7 mm galvanised steel wire mesh, positioned no more than 6 mm from the exposed surface.
  • Any material providing equivalent or better fire protection than 13 mm fire-protective grade plasterboard, installed according to standard trade practices.

Fire-resistance Level (FRL)

The measure of a building element's ability to withstand fire, assessed in minutes for structural adequacy, integrity, and insulation, listed in that order. A dash indicates no requirement for that specific criterion.

Fire-resisting Construction

Types of construction in Volume One that are designed to resist fire, as detailed in Part C2.


Applies to building elements in Volume One with an appropriate FRL, or in Volume Two to structural members or parts of a building that meet the required FRL.

Fire Safety Engineering

The application of engineering principles and expert judgement based on an understanding of fire, its effects, and human behaviour to design buildings that:

  • Protect life and property.
  • Quantify and mitigate fire hazards and risks.
  • Design, construct, and use buildings to reduce fire damage.
  • Determine the necessary protective and preventive measures for fire safety.

Fire Safety System

Methods used in buildings to warn of an emergency, enable safe evacuation, restrict fire spread, or extinguish fires, encompassing both active and passive systems.

Fire-source Feature


  • The boundary of a road, river, lake, etc., adjacent to the property.
  • A side or rear boundary of the property.
  • An external wall of another building on the property that is not a Class 10 building.

Fire Wall

A wall designed to prevent the spread of fire, dividing a building or storey into fire compartments.

Fixed Wired

Refers to electrical wiring systems, either AC or DC, that are permanently installed and supported in position, as specified in Specification 23.

Flammability Index

Determined by AS 1530.2, it is a number indicating the relative flammability of materials.


Materials used to prevent water ingress or to divert water away from sensitive areas, including:

  • Perimeter flashing: At the junction of floors and walls.
  • Vertical flashing: At wall junctions within shower areas.
  • Roof flashing: Over, against, or built into abutments for a weather-tight seal.


Refers to a fire reaching a heat release rate of 1 MW, indicating a rapid transition to a fully developed fire.


A series of steps or stairs uninterrupted by landings or floors, defined by the continuous slope of treads.

Flood Hazard Area

Land, identified by the appropriate authority, that is at risk of flooding, including areas below the flood hazard level.

Flood Hazard Level (FHL)

The level used to determine floor height in flood-prone areas, calculated as the defined flood level plus additional clearance (freeboard).

Floor Area

The total area of all storeys of a building, measured over enclosing walls and including mezzanines, internal structures, and if no enclosing walls are present, areas contributing to fire load or affecting occupant safety.

Floor Waste

A grated drain within a graded floor designed to remove surface water.


The supporting ground beneath a building, critical for structural integrity.

Fractional Effective Dose (FED)

A metric used in fire safety to quantify the dose of thermal effects that renders a person incapable of escape.


An additional height above the defined flood level, determined by the appropriate authority, to account for factors like wave action.

Fully Developed Fire

A fire condition where most available combustible materials are engaged, representing the peak of fire intensity.


Garage Top Dwelling

In NSW, a Class 1a dwelling situated above a Class 10a private garage, distinct from the dwelling and may include an internal staircase.


Transparent or translucent elements and their frames in a building's envelope, including windows but excluding roof lights, essential for natural lighting and insulation.


The horizontal distance measured from the front to the back of a stair tread, excluding any overhang from the tread above. This measurement is critical for stair design to ensure safety and comfort.

Green Star

A comprehensive building sustainability rating system administered by the Green Building Council of Australia, evaluating environmental design and construction aspects of buildings.


In theatrical settings, especially in New South Wales, a grid refers to the overhead framework used to support and manoeuvre stage scenery, lights, and equipment above the stage floor.

Group Number

A classification for materials based on their fire hazard properties, particularly relating to their use as finishes, surfaces, linings, or attachments to walls or ceilings, to regulate fire safety.


Habitable Room

A room intended for regular domestic activities, such as sleeping, living, dining, or studying. It includes bedrooms, living rooms, kitchens, and similar spaces but excludes bathrooms, laundries, and other non-regularly occupied spaces.

Hazard Rating

A classification reflecting the potential toxicity and contamination risk to drinking water systems, categorised as Low, Medium, or High Hazard, as per NCC Volume Three standards.

Health-care Building

Facilities designed to accommodate individuals requiring medical treatment, who generally need physical assistance to evacuate in emergencies, including hospitals, nursing homes, clinics, and day surgeries.

Heated Water

Water intentionally warmed for various uses, commonly referred to as hot or warm water, differing from ambient or cold water supply.

Heating Degree Hours

The measurement used for the number of degrees Celsius by which the mean outdoor air temperature, for any hour, is below 15°C, indicating the demand for heating to maintain comfortable indoor conditions.

Heating Load

The annual energy required to maintain desired temperature levels in the heated spaces of a building through artificial means, reflecting the building's thermal efficiency and insulation properties.

Heat Release

The amount of thermal energy produced during combustion, quantified in kilojoules (kJ), indicative of the fire's intensity and potential damage.

Heat Release Rate (HRR)

The speed at which heat energy is generated by a fire, measured in kilowatts (kW) or megawatts (MW), crucial for assessing fire growth and severity.

High Hazard

Conditions or practices associated with a water supply system that have the potential to cause severe health risks or fatalities.

High Wind Area

Regions classified as experiencing wind speeds exceeding N3 or C1 categories, requiring specific structural design considerations for buildings to ensure safety and stability.


A raised edge or barrier, often found around shower areas, designed to contain water and prevent it from spreading to other areas.

Horizontal Exit

A passage or doorway leading from one section of a building to another, separated by a fire-resisting construction, such as a fire wall, facilitating evacuation without leaving the building.

Hotel Offering Shared Accommodation

In Victoria, a hotel that provides sole-occupancy units designed for occupancy by unrelated individuals, incorporating shared living arrangements.

Hours of Operation

Refers to the period during which a building is occupied by more than 20% of its maximum occupancy, indicating its active use and the need for environmental control systems.

House Energy Rating Software

Software tools accredited under the Nationwide House Energy Rating Scheme (NatHERS), used for assessing the thermal performance of dwellings, available in both regulatory and non-regulatory modes for comprehensive energy efficiency evaluation.



The amount of luminous flux per unit area on a surface, measured in lux (lx), indicating the perceived brightness of illuminated spaces.

Illumination Power Density

The total power consumption of lighting in a given area, including all components of the lighting system, divided by the space's area, expressed in watts per square metre (W/m²), used to evaluate energy efficiency in lighting design.

Inclined Lift

A lift system designed to transport people up or down a slope within a carriage guided on one or more inclined tracks, differing from traditional vertical elevators.

Individual Protection

The use of a backflow prevention device installed at the connection point of a water service to a specific fixture or appliance, ensuring water safety and quality.

Information and Education Facility

As defined in the Standard Instrument—Principal Local Environment Plan, facilities designated for the dissemination of information and educational activities.

Insulation (FRL)

In fire-resistance terms, the capacity of a building element to maintain temperatures on its unexposed side within safe limits, as specified in AS 1530.4, preventing heat transfer during a fire.

Integrity (FRL)

The ability of a building element to resist the passage of flames and hot gases, maintaining its structural integrity and preventing fire spread, as defined in AS 1530.4.

Internal Wall

Walls within a building that do not function as common, party, or separating walls between different occupancy units or fire compartments, contributing to the internal layout and compartmentalisation.

Interstitial Condensation

Moisture formation within the layers of a building

Irrigation System

Types of irrigation systems categorised based on their installation and functionality:

  • Type A: Systems with all outlets and piping positioned more than 150 mm above the finished surface level, open permanently and not prone to backpressure or ponding, excluding those with injection systems.
  • Type B: Systems used in domestic or residential settings where piping or outlets are installed less than 150 mm above the surface level, excluding injection systems.
  • Type C: Non-domestic or non-residential irrigation systems with outlets less than 150 mm above surface level, also excluding injection systems.
  • Type D: Systems designed for the injection or siphoning of fertilisers, herbicides, nematicides, or similar substances.


The Joint Accreditation System of Australia and New Zealand, a body responsible for the accreditation of certification agencies and inspection bodies.


Lamp Power Density

The sum of the maximum power ratings of all lamps in a given space, excluding those intended for intermittent use and plugged into socket outlets, divided by the area of the space and expressed in watts per square metre (W/m²). This metric is utilised to establish an efficient level of energy consumption for lighting in buildings, particularly Class 1 and associated Class 10a buildings.


A flat area located at the top or bottom of a flight of stairs or between two flights, providing a rest point or transition between different stair sections.

Latent Heat Gain

The increase in heat within a space due to the vapourisation of liquids, which occurs without a change in temperature.

Lateral Support

Support structures such as footings, buttresses, cross walls, beams, floors, or braced roof structures that provide stability to a wall or pier by counteracting forces perpendicular to the wall's or pier's face.

Lead Free

Refers to plumbing products or materials in contact with drinking water that have a weighted average lead content not exceeding 0.25%, ensuring safety and compliance with health standards.

Licensed Premises

As defined in various legal contexts, premises that have been granted a licence to operate under specific regulations, including those serving alcohol under the Liquor Act 2007 in NSW, or under the Liquor Control Act 1988 in WA, which may include cabarets, taverns, hotels, or venues granted a special facility licence.

Lightweight Construction

Construction methods or materials that utilise components such as sheet or board materials, plaster, concrete products with lightweight aggregates (like pumice or vermiculite), or thin masonry less than 70 mm wide, which are susceptible to damage from impact or pressure.


Structural elements designed to carry additional vertical loads beyond their own weight, crucial for the stability and integrity of buildings.

Loadbearing Wall

Walls that support more than 10 kN/m of load in addition to their own weight, as specified for certain housing provisions, playing a critical role in the structural framework of buildings.


Refers to any form of detriment or negative impact, including physical damage, financial loss, or a reduction in amenity.

Low Hazard

Conditions, devices, or practices associated with a water supply system that might cause nuisance through colour, odour, or taste but are not likely to harm health or cause injury.

Low Rainfall Intensity Area

Areas characterised by a 5-minute rainfall intensity for an annual exceedance probability of 5% not exceeding 125 mm/hour, important for drainage and infrastructure planning.

Low-rise, Low-speed Constant Pressure Lift

A type of lift designed for low-rise applications, providing mobility for people with limited mobility, operated by constant pressure controls, suitable for buildings with minimal vertical travel requirements.

Low-rise Platform Lift

A lift system designed to assist individuals with limited mobility by raising or lowering a platform within a low-rise building, operated either automatically or through constant pressure controls.

Low Voltage

Electrical systems or circuits operating at a voltage higher than extra-low voltage but not exceeding 1000 V AC or 1500 V DC, commonly used in residential and commercial buildings.

Luminance Contrast

The difference in light reflectance between two surfaces or components, crucial for visual perception and safety, especially in design for accessibility.