Innovation in Modular Construction -

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Key planning requirements – STEP 1

To be allowed to build a granny flat it must:

  1. Be established in conjunction with another dwelling (the principal dwelling)
    • This means you cannot build a granny flat on a vacant block. If you are thinking of building a granny flat to live in while you knockdown & rebuild your house, you need to build your granny flat first.
  2. Be on the same lot of land as the principal dwelling
    • Granny flats cannot be built in connection with townhouses, strata developments or community title developments.
  3. Comprise one principal dwelling, one secondary dwelling
    • Subdivision is not permitted
  4. Be in the following development zones:
    • Zone R1 General Residential
    • Zone R2 Low Density Residential
    • Zone R3 Medium Density Residential
    • Zone R4 High Density Residential
    • Zone R5 Large Lot Residential (* may require development approval)

Note: Compliance with the above 4 key planning requirements does not guarantee approval of a granny flat on a property, but if your property meets the above 4 key requirements, then you move onto the next tests.

Specific site requirements - STEP 2

The next step involves the specific characteristics of your block. There are different requirements depending on the size of your block.

Minimum block size

If your property is less than 450 square metres (that is 450sqm), then you will not be able to build a granny flat on the property under current requirements.

Minimum street frontage

In addition to your property being larger than 450sqm, it must have a street frontage not less than 12 metres wide.

If your property has a frontage less than 12 metres wide, then you will not be able to build a granny flat on the property under current requirements.

As the block size gets larger, the requirements for minimum street frontages increase.

If the property is between 900sqm and 1500sqm, the minimum street frontage increases to 15 metres wide.

If the property exceeds 1500sqm, the minimum street frontage increases to 18 metres wide.  

The granny flat can be no larger than 60sqm.

Note: The 60sqm allowance is an approximage external dimension to the granny flat. The area inside the granny flat will be less to account for internal and external walls. The thicker the walls (ie brickwork), the smaller the area inside your granny flat.

Ascension Living currently offers rectagonal granny flats with external dimensions of 10m by 6m or 12m by 5m.

Note: The 60sqm allowance do not include garages, verandas, patios, outbuildings that maybe approved and built in conjunction with your granny flat. This means if your covered patio is 24sqm then your built area could be up to 84sqm in total.

Off street car parking for the granny flat is not essential.

Principal Private Open Space

The granny flat must have an outside entertainment area (ie a patio) that has an area of at least 24sqm, a width of at least 4 metres and must be directly accessible from a living room in the granny flat.

Note: You can add an external porch, deck, carport or garage to your granny flat in addition to your maximum 60m² building footprint.

For blocks between 450sqm and 900sqm, if your proposed granny flat is to be built in your backyard, it must be:

  • at least 3.0 metres from your rear boundary
  • at least 1.8 metres from the rear of your existing dwelling
  • 0.9 metres from both the side boundaries.

Where the property exceeds 900sqm, the property setbacks increase (similarly to how the minimum street frontages increase). These setback requirements are summarised in the table below.

If your property satisfies the necessary block sizes, frontages and setbacks, it is necessary to then consider floor areas and site coverage.

These are similar measures of the amount of development on your block of land.

Note: If there are easements on your property, the granny flat cannot normally be constructed on top of these and there are further distance setbacks that may be applicable.

Block (sqm) Minimum Frontage Height Front Setback Side Setback Rear Setback Landscape Area Maximum Floor Area Site Coverage
450-600 12m 3.8m 4.5m .9m 3m 20% 330m2 50%
600-900 12m 3.8m 4.5m .9m 3m 25% 380m2 50%
900-1500 15m 3.8m 6.5m 1.5m 5m 35% 430m2 40%
1500m2+ 18m 3.8m 10m 2.5m 10m 45% 430m2 30%

It is necessary to work out the floor area on your property taking into account the new granny flat. Floor area is calculated by adding the sqm area of your existing home (eg both levels for a two storey house) as well as any garages, carports, patios or awnings together with the proposed granny flat (which will be 60sqm).

The amount of permissible floor area depends on block size. For a property between 450sqm and 600sqm, the maximum floor area (including the new granny flat) is 330sqm. Accordingly, if the existing floor area exceeds 270sqm metres (before the new granny flat), then you will not be able to build a granny flat on the property under current requirements (as your new granny flat will take up 60sqm).

As the block size gets larger, the requirements for maximum floor area slightly increase and are summarised in the table below.

Site coverage differs from floor area as this calculation determines how much site is covered by built-up area. For instance a two storey building may have more floor area, but less site coverage than a one storey building. The best way to describe site coverage is that it is calculated by taking a bird’s eye view.

For blocks from 450sqm to 900sqm, the site coverage cannot exceed 50%. That means, the existing house and the proposed granny flat cannot together take up more than 50% of the total area of your block. 

Note: Remember this is calculated from your front boundary and does not include the Council’s nature strip.

The maximum site coverage is identified in the table below.

There is also a proportion of the property that requires a landscaping area.

Block (sqm) Minimum Frontage Height Front Setback Side Setback Rear Setback Landscape Area Maximum Floor Area Site Coverage
450-600 12m 3.8m 4.5m .9m 3m 20% 330m2 50%
600-900 12m 3.8m 4.5m .9m 3m 25% 380m2 50%
900-1500 15m 3.8m 6.5m 1.5m 5m 35% 430m2 40%
1500m2+ 18m 3.8m 10m 2.5m 10m 45% 430m2 30%

Landscaped Areas

Depending on your block size certain landscaped areas (eg turf & gardens) must be met. It needs to be remembered that your granny flat and any associated entertainment area will usually take up space that was previously turf or gardens.

For blocks between 450sqm and 600sqm, the minimum required landscape area is 20%. However, as a general rule, at least 50% of the required landscape area must be behind the main dwelling house.

The proportion of landscaping area required increases with lot size.

typical block

If you have a block exceeding 600sqm, some of the requirements change as detailed in the table below:

Block (sqm) Minimum Frontage Height Front Setback Side Setback Rear Setback Landscape Area Maximum Floor Area Site Coverage
450-600 12m 3.8m 4.5m .9m 3m 20% 330m2 50%
600-900 12m 3.8m 4.5m .9m 3m 25% 380m2 50%
900-1500 15m 3.8m 6.5m 1.5m 5m 35% 430m2 40%
1500m2+ 18m 3.8m 10m 2.5m 10m 45% 430m2 30%

Additional setbacks are required for granny flat buildings that exceed 3.8 metres in height (from the lowest point of natural ground level to top of roof).

If your block slopes and it is proposed to build the granny flat at a higher level than the principal dwelling, then additional privacy requirements may apply.

If your block slopes, there are various requirements in relation to the amount of excavation permitted near boundaries.

Note: Double storey granny flats are not offered for sale by Ascension Living at this time.

Different setback requirements may apply for corner blocks or battle-axe blocks.

As a general rule, granny flats are not able to be built closer than 3 metres from a significant tree truck (ie a tree exceeding 5 metres in height).

Additional requirements will be applicable if:

  • If your property is bushfire prone
  • If your property or a nearby property is heritage listed
  • If your property is flood prone

BASIX requirements are applicable.

Section 94 contributions are the developer’s (owners) contributions to the local council. Some councils impose section 94 contributions for the development of granny flats.

These contributions are separate to building cost and need to be paid to council before you receive an approval for your granny flat.

BASIX requirements are applicable.

If you want to know more, feel free to contact us for an obligation free discussion.

Ascension Living’s innovative modular construction system does away with the time consuming concrete slab on ground and frames and trusses construction stages adopted traditional home building construction. Instead, a structural module is craned into place on top of piers, then the building’s steel structure is completed with pre-fabricated structural elements and the building is secured a few days later (rather than several weeks using traditional building methods). Construction then continues in the traditional way with internal fixtures, furnishings and features.

Our Bijou granny flats are not kits, or shipping containers or pre-fabricated homes. The main points of difference are that the structure differs from a traditionally built house because of our innovative modular construction system. This system allows the house to be constructed much quicker.

Deliver of Bijou Granny Flat Contruction of Bijou Granny Flat

Inside construction of the Bijou Granny Flat

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