Patio & Shed Glossary WA
Plain-English definitions of WA patio, shed, engineering and approval terms
Buying a patio or shed in Western Australia comes with a lot of jargon — wind regions, terrain categories, footings, Z purlins, building permits and more. This glossary explains the terms in plain English so you can read quotes, compare kits and ask the right questions with confidence.
Quick Answer
This glossary defines the key patio, shed, engineering, materials and approval terms used across Western Australia. Understanding them helps you compare DIY kits accurately, understand what a quote includes and read the stated design basis in project documents. Browse by category below, or jump straight to a term.
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Choose a term to read its meaning.
Engineering
General structural terms used on patio and shed drawings and specifications.
Wind Region
A broad area used to help work out wind strength for a building.
Australia has wind regions A, B, C and D. WA covers more than one region. Your engineer uses the wind region with other site details. The region alone does not set the frame, footing, bracing or fixing details.
Terrain Category
A rating for how open or built-up the land is around your site.
Terrain category describes the land around your site. Open ground differs from a built-up suburb. It is one part of a wind check. A professional must set the rating and work out how it affects your project.
Engineer Certification
Documents from an engineer about a set design and its design rules.
Engineer certification covers the design, facts and standards named in the documents. It only covers the stated project scope. It does not approve planning, a building permit or later design changes. Ask the permit authority or building professional which documents you need.
Footing
The base that carries a structure's weight into the ground.
A footing spreads the structure's load into the ground. Patio and shed footings are often concrete. Their type, size and depth depend on the design, site and soil.
Span
The distance between two supports, such as posts, without another post in the middle.
A span is the space between two supports. It is one part of the structural design. The full design sets the right part sizes and supports.
Structural Member
One part of a structure that carries weight or force.
A structural member is one load-carrying part. It may be a post, beam, rafter, purlin or girt. Each part has a set place and job in the design.
Column
An upright part that carries weight down to its support.
A column is an upright part of the main frame. It may also be called a post. Check your drawings for the term used in your project.
Beam
A strong part that runs between supports and carries weight.
A beam is often flat or sloped. It carries weight to posts, walls or other supports. Your drawings show its exact job.
Rafter
A sloping frame part that runs down the roof.
A rafter is part of the roof frame. It holds up the roof parts above it. It may be in the main frame or sit on other frame parts.
Purlin
A roof frame part that holds up the roof sheets.
Purlins run across rafters or main frames. They give the roof sheets extra support. They come in different shapes and materials. A Z purlin is one common steel shape.
Girt
A wall frame part that holds wall sheets between main frames.
Girts usually run across a wall. They carry force from the wall sheets to the main frame. The building design sets where they go.
Mullion
A vertical framing member used within a wall or beside an opening.
A mullion is an upright support in a wall or beside a door. Your project design sets its place, size and joins.
Bracing
Parts that help stop a structure from moving.
Bracing works with the frame and joins to keep a building stable. Your drawings show the type and where it goes.
Cleat
A small part used to join two frame parts.
A cleat is a plate or shaped part at a join. The project design sets the cleat and fixings. Do not choose them by looks alone.
Batten
A smaller frame part that holds sheets, lining or another part.
Battens are small supports fixed across or between the main frame. Their job depends on what they hold up.
Portal Frame
A main structural frame made from connected columns and rafters.
A portal frame joins posts and rafters into one main frame. This can leave a clear space inside. A shed may have many portal frames. Smaller frame parts hold the roof and wall sheets between them.
Connection
The place and method by which two or more building parts are joined.
A connection joins members or components so forces can pass between them. Connections may use bolts, screws, welds, brackets or other details, but the required detail is specific to the project drawings and supplied instructions.
Opening
A planned gap in a wall or roof, such as a door, window or access opening.
An opening interrupts the surrounding cladding and may also affect framing layout. Its location and dimensions should be read from the project drawings; changing an opening can change the design basis.
Approvals
The permits and approvals you may need before building — these vary by local government area.
Building Permit
An approval issued by the permit authority when current rules require it.
A building permit is official approval for building work. You may or may not need one. This depends on your project, property and current rules. Ask the permit authority what you need before you build.
Planning Approval
A separate approval that looks at where your patio or shed will be built on your property.
Planning approval is different from a building permit. Planning approval looks at where your patio or shed will be built on your property, and can include things like how close it is to boundaries, how tall it is and whether there are special rules in your area. Some projects need planning approval, some need a building permit, some need both and some may not need either. The rules can be different depending on where you live, so it is best to check with your local council before you build.
Certified Building Permit Application
A BA1 building permit application lodged with a Certificate of Design Compliance.
A certified building permit application (BA1) is lodged with a Certificate of Design Compliance (BA3) signed by a registered building surveyor. The permit authority still assesses the application; certification does not guarantee that a permit will be granted.
Uncertified Building Permit Application
A BA2 pathway for eligible Class 1a and Class 10 building permit applications.
An uncertified building permit application (BA2) is available only for eligible Class 1a and Class 10 projects. The permit authority carries out assessment and certification in that pathway; eligibility and approval must be confirmed for the project.
Certificate of Design Compliance
A BA3 certificate from a registered building surveyor used with a certified application.
A Certificate of Design Compliance (BA3) is issued by a registered building surveyor for a certified building permit application. Its scope and suitability are project-specific, and it is not itself a building permit.
Permit Authority
The authority with the statutory role of receiving and deciding a building permit application.
A permit authority receives and checks building permit applications. It makes the permit decision under its legal role. Check with the right authority about your property and project.
Local Government
The local public authority for an area, with roles that can include planning and permit functions.
A local government is the public authority for a defined area. It may have planning and permit-related roles, but the applicable process and requirements depend on the project and current rules.
Development Approval
A planning decision about a proposed development, separate from a building permit.
Development approval is a planning decision that can address matters such as land use, siting, setbacks, height and applicable planning controls. It is separate from a building permit, and one approval does not automatically replace the other.
Owner Builder
A person who manages their own building project instead of hiring a builder to do everything.
An owner-builder manages building work on their own property. In WA, a homeowner can build a Class 10a patio or shed without owner-builder approval if the building work is valued at less than $50,000. This rule changed on 1 July 2026. A building permit, planning approval or other council approval may still be needed. The threshold is based on the value of the building work, not just the kit price.
Materials
Plain-English names for steel sections, roofing, walling, cladding and coatings.
Colorbond
A brand of pre-painted steel products commonly used for building components in Australia.
COLORBOND® steel is a branded, pre-painted steel product used for items such as roof and wall cladding, gutters and fascia. It is not a generic name for every coloured or coated steel product; when comparing materials, check the product named in the quote or specification.
Insulated Roofing
A special type of roof that helps keep patios and sheds cooler.
Insulated roofing combines roof skins or sheets with an insulating layer. Its thermal and acoustic performance varies by product, thickness, installation and site conditions, so those properties should be checked in the relevant product information.
Cladding
The outer sheet or panel material fixed over a building's roof or wall framing.
Cladding forms an external covering rather than the main load-carrying frame. Roof cladding and wall cladding have different locations and may use different profiles, finishes and fixing details.
Roofing
The materials and components that form the weather-facing roof covering.
In kit descriptions, roofing commonly means roof cladding or roof panels and may also refer more broadly to associated flashings and fixings. A quote or component list should identify exactly what is included.
Walling
The sheets or panels used to form a building's external walls.
Walling is another name commonly used for wall cladding. It is fixed to wall framing such as girts and is separate from the building's main structural frame.
Framing
The connected members that support a building and its roof or wall coverings.
Framing is the supporting arrangement of members such as columns, beams, rafters, purlins and girts. Main framing carries loads through the primary structure, while secondary framing supports components such as roof and wall cladding.
Coated Steel
Steel with a protective metallic, painted or combined coating applied to its surface.
Coated steel is a broad description rather than one particular brand or product. Coating systems, finishes and intended uses vary, so a product name and specification are more precise than terms such as coloured steel or coated metal.
Fascia
A finishing board or member along a roof edge, often associated with the gutter.
Fascia runs along a roof edge and can provide a finished face or support for associated components such as guttering. Its presence and structural role must be established for the particular building rather than assumed from appearance.
Patio Styles
The common patio designs available across Western Australia.
Attached Patio
A patio fixed to the home, typically using the house wall or fascia as one line of support.
An attached patio connects directly to the house, extending the existing roofline or attaching to the wall. It is the most common patio type for adding shade and outdoor living space close to the home.
Freestanding Patio
A self-supporting patio that stands on its own posts, independent of the house.
A freestanding patio is supported entirely by its own posts and is not attached to the home. This style suits pool areas, entertaining zones and locations away from the house, and gives more freedom in positioning and orientation.
Raised (Flyover) Patio
A patio set higher than the home's existing roofline to allow extra height, light and airflow underneath.
A raised or flyover patio is mounted above the existing gutter line, creating a higher, more open feel and allowing more natural light. It suits sloping blocks, second-storey clearances and larger entertaining areas.
Gable Patio
A patio with a pitched, triangular roof that creates extra height, ventilation and a feature roofline.
A gable patio has a pitched roof that rises to a central ridge, creating a sense of space and improving airflow. Gable designs are one of WA's most popular patio styles for larger outdoor living areas.
Roof Pitch
The amount and direction a roof surface slopes.
Roof pitch describes the slope of a roof surface. It influences the roof profile, the direction water travels and, for pitched forms, the relationship between the roof edge and ridge or apex; the suitable pitch is project- and roofing-specific.
Gutter Height
The level of a roof gutter at the roof edge, rather than the clear space below a patio.
Gutter height identifies the level of the gutter at a roof edge. It is not automatically the same as eave height, attachment height, beam underside, usable headroom or the roof's ridge or apex.
Eaves (Eave)
The lower roof-edge area, often projecting beyond the outside wall and associated with the gutter line.
An eave is the overhanging roof-edge area beyond an external wall. It can include or sit near fascia, gutter and the underside lining, so drawings or measurements should identify the exact feature being referenced.
Ridge
The upper line where two sloping roof planes meet.
A ridge is the high line formed where sloping roof planes meet, as on a gable roof. It is different from an edge or gutter level and may not apply to every roof form.
Headroom
The usable clear vertical space beneath a roof, beam or other overhead part.
Headroom is clear space available below the lowest relevant overhead component. It is not the same as gutter, eave, attachment, ridge or apex height, and the controlling component depends on the complete design.
Shed Types
The main shed configurations used by WA homeowners and businesses.
Awning
A roofed extension projecting from the side of a building.
An awning can provide covered access, work or storage space beside a building. The term and framing arrangement can vary between building systems, so the project documents define what applies.
Annexe
An attached roofed extension alongside a main building.
An annexe is an attached extension that can add covered space beside a shed or commercial building. The terms annexe, lean-to and awning can be used differently between systems, so confirm the intended configuration in the quotation and drawings.
Apex
The high point of a pitched or gable roof.
The apex is the uppermost point of a gable or pitched roof, commonly at the ridge. It is different from the lower eaves or gutter line and does not apply to every roof form.
Buying
The terms you will see on quotes and in DIY kit packages when comparing suppliers.
Bill of Materials (BOM)
A project list of the materials and components identified for a building package.
A bill of materials, or BOM, lists the parts for a project or kit. Read it with your quote and drawings. The exact kit contents can vary.
Factory Direct
Buying a kit directly from its manufacturer rather than through a separate retailer.
Factory direct describes the sales path, not the contents, price or engineering status of a kit. Compare the written inclusions, exclusions, documentation and total quoted cost when assessing different offers.
DIY Kit
A package of patio or shed components intended for the customer or chosen trades to assemble.
DIY means you arrange or do the assembly. It does not mean every part, approval or engineering document is included. Your quote, parts list, drawings and instructions show what your kit includes and what your project needs.
Approval Information
The information on this page is only a general guide.
Building permit, planning approval and owner-builder rules can differ by location and project. They can also change.
Before you order or build, ask your council or permit authority what applies. A qualified building professional can also help.
Key Facts
- WA spans several wind regions, from the lower-wind south-west to higher-wind coastal and cyclonic zones.
- Wind region and terrain category are among the project inputs used to establish wind design actions.
- Engineer certification has a defined scope and does not itself grant planning or building approval.
- Z purlins are cold-formed steel members used as secondary framing to support a shed's roof and wall cladding.
- COLORBOND® steel is a brand of pre-painted steel, not a generic term for every coated steel product.
- Your quote, parts list and project documents show what comes in a DIY kit.
Key Takeaways
- Wind region and terrain category are among the inputs considered when a patio or shed is designed for a particular site.
- Engineering documents and approval rules depend on your project, site and authority.
- Roof cladding, wall cladding and framing are different parts of a building; a quote should identify what is included.
- Shared terminology helps you compare written inclusions, but similar descriptions do not prove that two kits are equivalent.
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