Granny flat builders

When this is the right path, and when it is not

How the job actually runs

1. 01
   Check whether it is exempt or needs a permit

   Some states allow a compliant secondary dwelling without full planning assessment. Whether yours qualifies turns on lot size, setbacks and floor area.

2. 02
   Confirm the minimum lot size

   This is usually the gate. Where a minimum lot size control is mapped, it decides whether a second dwelling is possible at all.

3. 03
   Work out services

   Sewer, water, power and sometimes a separate meter. On an established block the connection path is often the expensive surprise.

4. 04
   Decide built on site or transportable

   Modular and transportable options have shorter, more predictable programmes. Access for delivery decides whether they are possible.

Where these jobs go wrong

The four things that most often cost people money on a granny flats job specifically.

• Assuming your block qualifies

  Minimum lot size is usually the gate, and it varies by suburb and council. Where a minimum lot size control is mapped, check it before you spend money on a design.

• Underestimating the service run

  Sewer, water and power from the street or the existing house to the back of the block is often the single biggest line item, and it is invisible on a floor plan.

• Not checking whether you can rent it out

  Occupancy rules vary by state and council. Some permit separate tenancy, some restrict it to family. Settle this before you build, not after.

• Losing the tree

  Established trees and their protected root zones frequently decide where a second dwelling can physically go. An arborist before a designer saves money.

What moves the price

No figures — a number without your site and your specification is a guess. For a granny flats job, these are what actually move it.

• Service connections and separate metering
• Access for machinery down the side of an existing house
• Existing trees and their protection
• Whether a planning permit is required
• Site fall and retaining

Where we cover this, and what the planning data says

Minimum lot size is the control that most often decides how a granny flats job runs. Read from state planning data.

Suburb-level, read from state planning data. Not a report on any individual block.

What to ask a builder about a granny flats job

Specific to this kind of job. The general list is in questions to ask a builder.

• Does my block meet the minimum area and frontage for a second dwelling here?
• Is this an approval as a secondary dwelling, or does it need a full development application?
• Can it be separately metered, and can it be rented out under this council's rules?
• How will you get machinery and materials to the rear of the block?
• What happens to the existing house's services, drainage and private open space?

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