Key Planning Considerations for a Double Storey Extension in Melbourne

Before designing a double storey extension, it is important to understand the planning controls and site constraints that may influence what can actually be built.

Building height, setbacks, overlooking, overshadowing, heritage controls and the existing structure of the home can all affect the size, position and design of an upper-floor addition.

This guide focuses specifically on the planning considerations that should be checked before designing a double storey extension in Melbourne. For the complete project sequence from feasibility through construction, see our double storey extension planning guide.

Check the Planning Controls Before Finalising the Design

Every property has its own planning context. Two homes in the same suburb can be affected by different zones, overlays, lot dimensions and neighbouring development.

Before committing to a floor plan, establish which controls apply to the property and whether they are likely to restrict the proposed upper floor.

Important issues can include:

• maximum building height
• side and rear setbacks
• front setback requirements
• overlooking of neighbouring properties
• overshadowing
• site coverage
• private open space
• heritage overlays
• neighbourhood character
• significant vegetation or other overlays

Building Height and Upper-Floor Setbacks

Adding another level changes the height and visual impact of the home, so the upper floor needs to respond to the planning controls applying to the site.

Upper-level walls may need to be set back further than the ground floor to reduce visual bulk, protect neighbouring amenity and satisfy planning requirements.

This can affect how much usable floor area is available upstairs and should therefore be considered before bedrooms, bathrooms and other spaces are positioned.

Why Setbacks Matter to the Floor Plan

A setback is not simply a planning issue. It directly affects the shape and dimensions of the upper floor.

If a wall needs to move inward, bedroom sizes, wardrobes, bathrooms and circulation areas may all need to change. Good planning integrates these constraints into the initial concept rather than trying to correct the design later.

Overlooking and Privacy

Upper-floor windows can create new views into neighbouring properties, particularly private open spaces and habitable-room windows.

Depending on the design and site relationship, privacy may need to be addressed through:

• window positioning
• raised sill heights
• obscure glazing
• privacy screens
• careful room orientation
• changes to balcony locations

Considering privacy early usually produces a better result than designing the preferred window layout first and then adding screening simply to achieve compliance.

Overshadowing and Neighbouring Properties

A second storey can change how sunlight reaches neighbouring yards and buildings.

The effect depends on the height and position of the proposed extension, the orientation of the site and the relationship between the homes.

Where overshadowing is a concern, the design may need changes to wall positions, upper-floor setbacks, roof forms or overall building height.

Heritage Overlays and Character Homes

Many Melbourne suburbs contain Victorian, Edwardian, Federation and other period homes that are affected by heritage controls.

Where a heritage overlay applies, the objective is often to preserve the important character of the original building and streetscape while allowing appropriately designed new work.

A second storey may need to be positioned so that it has limited visibility from the street or uses a form, scale and material palette that responds appropriately to the existing building.

For projects where heritage considerations dominate the design, see our heritage renovation and extension services in Melbourne.

Existing House Structure and Planning Should Be Considered Together

A planning-compliant design still needs to be structurally practical.

The proposed upper floor needs to work with the existing footings, walls, framing and staircase location. Moving the upper level simply to satisfy a planning constraint can sometimes create additional structural complexity downstairs.

This is why planning, design and structural feasibility should be considered together rather than as separate stages.

Site Access Can Influence the Design

Restricted access does not usually determine whether planning approval can be obtained, but it can influence whether the approved design is practical and economical to construct.

Narrow side access, neighbouring buildings, overhead services, established landscaping and limited space for scaffolding or material storage should all be identified during the early planning stage.

A design that is technically possible but extremely difficult to construct may not be the best solution for the property.

Do You Need a Planning Permit?

Not every double storey extension follows exactly the same approval pathway.

Whether a planning permit is required depends on the planning controls applying to the property and the details of the proposed design.

A building permit is a separate approval and is required before structural building work begins.

Where a planning permit is required, the planning approval process will generally need to be completed before the building permit can be issued.

Planning Permit vs Building Permit

A planning permit considers whether the proposed development is acceptable in relation to planning controls such as setbacks, overlooking, neighbourhood character and heritage.

A building permit deals with whether the documented building work complies with applicable building regulations and technical construction requirements.

The two processes have different purposes and should not be treated as interchangeable.

Planning Considerations for Melbourne Family Homes

The best design is not simply the largest upper floor that can fit within the planning controls.

The planning stage should also consider how the extension improves the way the household uses the property.

This may include:

• keeping children’s bedrooms together
• creating a separate parents’ area
• adding an upstairs retreat
• improving natural light
• retaining backyard space
• protecting privacy between neighbouring homes
• maintaining the character of the original house
• allowing future flexibility as family needs change

What to Check Before Starting the Design

Before developing detailed plans for a double storey extension, it is useful to establish:

• the planning zone applying to the property
• any overlays affecting the site
• existing property dimensions and levels
• the position of neighbouring buildings
• likely overlooking and overshadowing issues
• heritage requirements where applicable
• the existing structural system
• possible staircase locations
• site access for construction
• the family’s required rooms and priorities

Resolving these issues early allows the concept design to respond to the actual property rather than relying on assumptions that may later need to be redesigned.

Considering a Double Storey Extension in Melbourne?

Planning controls are only one part of determining whether an upper-floor addition is right for your home. The design also needs to work structurally, financially and practically.

Cameron Construction manages design, engineering, approvals and construction for double and second storey extensions across Melbourne.