How to read house plans in Australia

What are house plans, and who reads them?

Consumer and Business Services, in its January 2025 consumer guide, describes drawings as “the visual instructions or plans given to the builder and local council detailing the measurements and features of the property being constructed.” The same guide notes that “The plans, specifications and technical details will be used by the council to approve the project and by the builder to quote and build.”

A set is made of several drawing types, each answering a different question. What the whole documentation set contains, and what each part decides, is covered in a separate note; this one is about reading the drawings themselves.

• What a building documentation set contains

How do you read a site plan for a house?

A site plan is the drawing of the whole block. PlanSA states that “All applications require a site plan which shows the location of the proposed development and its surrounds.” It says a site plan may include the dimensions and boundaries of the site, proposed boundary setbacks, existing buildings, trees, retaining walls and other structures, any on-site sewerage or waste disposal system, driveway levels and car parking spaces, and existing and proposed ground and floor levels. Its planning checklist adds that a relevant authority “may choose to waive the documentation requirement if it is deemed appropriate to do so.”

PlanSA’s planning checklist asks for a site plan “drawn to scale, including appropriate bar and ratio scales”, and its rows include the minimum distance between the proposed building and the front, side and rear boundaries, the location of any regulated tree on the site or adjoining land, and a north point. The north point orients the drawing, and the boundary distances show where the building sits on the block.

• Regulated and significant trees before building in Adelaide

How do you read a floor plan?

PlanSA describes floor plans as “drawings to scale of either 1:100 or 1:200 as a view from above”, showing the position of doors or windows, the relationship to an associated dwelling, and the location and purpose of rooms and areas.

PlanSA adds that floor plans “may also include details of fixtures like sinks and water heaters” and may have “notes for construction to specify finishes, construction methods, or symbols for electrical items.” For an extension or renovation, it says: “Alterations to existing buildings should indicate proposed changes to the structure and what is being retained.”

• Home extensions in Adelaide

How do you read floor plan dimensions and scale?

On dimensions, PlanSA states: “Dimensions are usually drawn between the walls to specify room sizes and wall lengths.” Before relying on a figure, check what the dimension line runs between and which unit the drawing uses, which is stated in the notes on the sheet where the drawing gives it. Reading the written figure avoids errors from measuring a print that is not at its intended scale.

A ratio scale such as 1:100 means the drawing is one hundredth of full size, so 10 mm on the sheet stands for 1 m. That only holds when the sheet is printed at the paper size it was set up for. A bar scale is drawn on the sheet itself, so it grows or shrinks with the print. PlanSA’s planning checklist asks for site plans and elevations to include “appropriate bar and ratio scales”. PlanSA’s building checklist asks for floor plans, elevations and sections “drawn to a scale not less than 1:200”, and site plans “not less than 1:500”.

What do elevations and sections show?

PlanSA describes elevation drawings as “a view of the home drawn to show other details that give a building its architectural styling”. It lists what they show as front, side and rear views; existing and proposed ground levels; proposed internal floor levels; “heights including ceilings, eaves, ridge, pitch”; a description of all external materials and finishes; the dimensions of eaves, external doors and windows; privacy treatments for upper-level windows or balconies; and details of existing ground level, proposed floor level and roof height. Its planning checklist adds building height “both to the gutters and to the maximum roof ridge”.

PlanSA’s building checklist lists “elevations and sections” together, drawn to a scale not less than 1:200, among the drawings expected with an application for building consent; the PlanSA guidance read for this note does not describe sections further. Ceiling heights read from a section or elevation can be compared with the room height provisions explained in a separate note.

• Minimum ceiling heights for a new house in SA

What are details, schedules and the other drawings in a set?

PlanSA says that where an application involves building work, it may also need roof, wall and floor layouts “including dimensions and calculations”, details of construction materials and design, engineering details, and a schedule of colours showing the proposed materials, finishes and colours. Its building checklist also lists rows including specifications and the “sizes and locations of footings and other structural components”.

YourHome, the Australian Government’s guide to sustainable homes, describes the documents at the detailing stage as typically including “working drawings (details of how the design is to be built)”, “a specification of the materials, standards, finishes, and products to be used” and “engineering design and certification”.

• From feasibility to schematic design

What do the symbols and abbreviations on house plans mean?

No single list read for this note applies to every set of Australian house plans, so this note does not give an abbreviation table. PlanSA mentions “symbols for electrical items” as something a floor plan may carry, without defining them. The meaning of a symbol or abbreviation is whatever the drawing set itself says.

Where a set has a legend, notes or a schedule that keys symbols and codes, that is the place to read them. Where it does not, the person who prepared the drawings can say what each mark means. It is worth asking before signing anything that refers to the drawings, since a contract and a price are both read against them.

• Design and planning

Who decides whether a set of plans is enough for approval?

PlanSA states that the documentation for a development application “is set out by Schedule 8 of the Planning, Development and Infrastructure (General) Regulations 2017” and that “The level of documentation you’ll need depends on what you are proposing.” Its building checklist says that if an application is lodged without the expected information, “the relevant authority may request additional information reasonably required to assess the application”. Its planning checklist adds that a relevant authority “may choose to waive the documentation requirement if it is deemed appropriate to do so.”

PlanSA defines the relevant authority as “the decision-maker who assesses the development application”, which “could be an Assessment Manager from council, an independent accredited professional, State Planning Commission or relevant panel.” Which drawings a particular proposal needs is confirmed with the relevant authority for that address.

• Planning consent, building rules consent and development approval in SA