North Sydney 2060 · North Sydney Council
Granny Flat Builders in North Sydney: Converting What's Already There
The best granny flat on your lot might already be standing.
North Sydney's houses sit on blocks of 250 to 500 square metres, often terraces and Federation homes in heritage areas. A new detached flat rarely fits. But a lot of these properties have an under-house level, a rear garage or an old outbuilding that could become a proper second dwelling, if it's upgraded to today's standards.
Short answer
Can I convert a garage into a granny flat in North Sydney?
Yes, if the space can meet the building code for a dwelling: a habitable ceiling of at least 2.4m, natural light and ventilation, damp protection, fire separation and proper services. Conversion avoids new footings and keeps the backyard. North Sydney DAs take 13 to 18 weeks, construction runs about $2,750 to $3,310 per m², and flats near the Metro rent for $700 to $950 a week.
Written and reviewed by Oliver Alameri
Licensed builder, NSW Contractor Licence 487805C · Founder, Buildana
Fact-checked
A garage isn't a home until the code says so
Turning a garage, basement or storeroom into somewhere people live is a change of use. It needs approval, and in North Sydney's heritage areas that almost always means a DA. It also has to meet the National Construction Code for habitable rooms, which most existing spaces don't.
The usual gaps: ceiling height, daylight, ventilation, damp and fire separation from the main house. Each one is fixable. Some are cheap, some aren't, and the combination decides whether conversion beats building new.
An illegal granny flat is a liability. A converted one done properly is an asset.
What the space has to achieve
The code's usual minimum for a habitable room in a house is 2.4 metres floor to ceiling. Basements and old garages often fall short, and lowering a floor or raising a roof is where conversion costs climb.
Light and air matter too. The code expects windows with a glazed area of around a tenth of the room's floor area, and openable area of about a twentieth for natural ventilation, or mechanical ventilation where that can't work.
Below ground, damp is the enemy. Walls and floors against soil need proper waterproofing and drainage, and on North Sydney's sandstone, water tracks along the rock face straight into cut-in rooms.
- 2.4 metres floor to ceiling in bedrooms and living areas
- Windows sized for daylight, and openable for air
- Waterproofing and drainage for walls against the ground
- Fire and sound separation where the flat adjoins the house
- Its own entry, kitchen, bathroom and laundry
Have a space that could be a flat?
Send photos of the garage, basement or outbuilding and the North Sydney address. I'll spell out what it needs to become a legal, comfortable dwelling, and whether converting beats building new.
0476 300 300When conversion wins, and when it doesn't
Conversion wins when the structure is sound, the ceiling is already close to 2.4 metres and there's a way to get daylight in. It avoids new footings, rock excavation and a new roof. It also keeps the backyard.
It loses when the floor has to be dug down into sandstone, the space has no outside wall for windows, or the heritage controls won't allow new openings on a visible elevation. Then a small new building, if the lot allows one, is often simpler.
We look at both before anyone draws a line.
Approval and cost in North Sydney
A house DA in North Sydney usually needs thirteen to eighteen weeks, often longer in heritage conservation areas. The secondary dwelling has to meet the state's size limits unless local controls allow more.
North Sydney's cost loading of 1.25 on the Rawlinsons schedule means mid-range work here lands near $2,750 to $3,310 a square metre. Conversions vary more than new builds, so we price them after a structural and moisture inspection.
Close to the Metro and the office towers, a well-finished secondary dwelling rents for around $700 to $950 a week.
Conversion checklist for North Sydney
Six questions that decide whether your existing space can become a legal dwelling.
- 01
Existing ceiling height, measured at its lowest point
- 02
An external wall where windows can go
- 03
Signs of damp or water tracking along rock
- 04
Heritage controls on any visible elevation
- 05
Separation from the main house for fire and sound
- 06
Room for a separate entry and services
Conversion questions
Can I convert my garage into a granny flat in North Sydney?
Often, with approval. It's a change of use, so it needs a DA in most North Sydney cases, and the space must be upgraded to meet the building code for habitable rooms.
How high does a granny flat ceiling have to be?
Bedrooms and living areas generally need 2.4 metres. Bathrooms, laundries and some other rooms can be lower.
Is a basement granny flat allowed?
It can be, if it achieves the required ceiling height, daylight, ventilation and waterproofing, and gets approval. Damp is the main challenge on North Sydney's sandstone.
How much rent could a converted flat earn here?
Around $700 to $950 a week for a well-finished secondary dwelling, given the Metro and CBD nearby.
Sources and references
Costs are from the Rawlinsons handbook with the local cost index applied; rules and timeframes are checked against the sources below.
Use what you've got. Make it legal. Make it good.
A North Sydney conversion that meets the code and adds real value to your home.