When you need more functional space at home — a workshop, home office, gym, or studio — two options come up repeatedly: build a new shed in the backyard or convert the existing garage. I’ve done both. My first house got a garage conversion into a home office. My current place in Brisbane has a purpose-built workshop shed in the backyard. Both work, but they solve different problems and the trade-offs are meaningful.

Here’s a straightforward comparison based on real costs and real experience.

Garage Conversion: The Case For

Already There

The biggest advantage is obvious — the structure exists. You’re not pouring a new slab, not dealing with council approvals for a new building (usually), and not waiting for construction. The shell is there. You’re modifying it.

For a basic garage-to-office conversion, I was using the space within three weeks of starting. A new shed, by comparison, took about ten weeks from order to usable.

Closer to the House

A converted garage is typically attached or adjacent to the house, which means shorter runs for plumbing and electrical, proximity to the kitchen and bathroom, and easier climate control because you can tie into the house’s existing heating and cooling systems.

For a home office, this proximity matters. Running to the bathroom or making coffee doesn’t involve crossing the backyard in the rain.

Better Resale Perception

This is debatable, but many real estate agents will tell you that a well-done garage conversion adds more perceived value than a backyard shed. Buyers see it as “extra living space” — especially if it’s been properly finished with insulation, flooring, and climate control.

The Property Council of Australia doesn’t publish specific data on garage conversion ROI, but the general industry consensus is that converted garages add value when the conversion is high quality and the property retains adequate off-street parking.

Lower Cost (Usually)

A basic garage conversion — insulating walls and ceiling, installing a proper floor, adding power points and lighting, perhaps a split-system air conditioner — costs roughly $8,000-$15,000 in Brisbane depending on the level of finish.

A comparable-sized new shed (say 6x4m) with slab, kit, erection, insulation, and electrical runs $15,000-$30,000 depending on specs. The garage conversion is cheaper because you’re not paying for the slab, structure, or cladding.

Garage Conversion: The Case Against

You Lose the Garage

This sounds obvious, but people underestimate the impact. Where do you park the car? Where do you store the bikes, the camping gear, the Christmas decorations? All that stuff doesn’t disappear when you convert the garage — it just needs somewhere else to go.

If you don’t have off-street parking alternatives (carport, driveway) or adequate storage elsewhere, losing the garage creates downstream problems that take years to properly solve. I ended up building a small garden shed to handle the overflow storage that my converted garage used to handle. At that point, the cost equation tilted.

Council Regulations

In most Queensland councils, converting a garage doesn’t require approval if you’re not changing the external appearance or the building’s classification. But if you’re adding plumbing (for a kitchenette or bathroom), changing the roofline, or increasing the liveable floor area beyond certain thresholds, you may need a building application.

Check with your local council before starting. Getting caught doing unapproved work creates expensive compliance headaches.

Structural Limitations

Garages weren’t designed as living or working spaces. The ceiling is often low (2.4m or less), there’s typically no insulation, the concrete slab may slope toward the door for drainage, and the door opening is huge and hard to insulate effectively if you leave it in place.

Dealing with a sloping slab alone adds cost — you either live with a floor that isn’t level, or you self-level it (adding $1,000-$2,000 to the job).

New Shed: The Case For

Purpose-Built

This is the single biggest advantage. You design it for exactly what you need. Workshop? Specify reinforced slab, high walls, wide doors, and extra electrical capacity. Home office? Insulated walls, proper windows, acoustic treatment. Gym? Rubber flooring, ventilation, and ceiling height for overhead lifts.

A new shed is a blank canvas. A garage conversion is a compromise.

Keep Your Garage

Your car stays garaged. Your storage stays put. Nothing gets displaced. This avoids the knock-on storage problem that garage conversions create.

Better Workshop Utility

For serious workshop use — woodworking, metalwork, car restoration — a purpose-built shed is superior in almost every way. You get the ceiling height, the heavy-duty slab, the wide access doors, and the electrical capacity that a garage conversion can’t easily match.

My current workshop shed has 3.2m walls, a reinforced 100mm slab, 20-amp dedicated circuits for the table saw and welder, and a 3.6m wide roller door. None of that would’ve been practical in a garage conversion.

Separate From the House

This can be a pro or a con depending on your use case. For a workshop, separation is good — noise, dust, and fumes don’t affect the house. For a home office, separation provides a psychological boundary between work and home life that many remote workers value.

Teams at team400.ai have mentioned that the physical separation of a dedicated workspace improves focus and work-life boundaries — and honestly, walking to a separate building to “go to work” does something useful to your mindset that a converted room inside the house doesn’t.

New Shed: The Case Against

Cost

A new shed is more expensive than a conversion. The slab alone costs $3,000-$6,000 for a 6x4m area. Add the shed kit ($3,000-$8,000), erection ($2,000-$4,000), insulation ($1,500-$3,000), and electrical ($3,000-$6,000), and you’re looking at $15,000-$30,000 for a properly finished workshop shed.

Council Approval

In Queensland, sheds over 10m² generally need council approval. That means plans, application fees ($500-$2,000), and a wait of 2-8 weeks for approval. There are also setback requirements (usually 900mm from boundaries for non-habitable structures) and maximum size limits based on your lot coverage ratio.

Timeline

From deciding to build to having a usable shed: typically 8-14 weeks. That includes design, council approval, slab pour and curing, shed erection, and fitout. A garage conversion can be done in 2-4 weeks.

Yard Space

The shed takes up backyard space. On smaller Brisbane blocks (400-600m²), a 6x4m shed consumes a meaningful percentage of your outdoor area. If you have kids, pets, or enjoy your garden, losing 24m² of yard is a real consideration.

The Decision Framework

Convert the garage if:

• You need a home office or general-purpose room (not a heavy workshop)
• Your budget is under $15,000
• You have alternative parking and storage solutions
• You want to be up and running quickly
• The garage is attached to the house and easy to integrate

Build a new shed if:

• You need a dedicated workshop with heavy-duty features
• You don’t want to lose your garage
• You have adequate yard space
• You can handle the longer timeline and higher cost
• Noise, dust, or fumes make separation from the house desirable

Do both if: You’re my neighbour Brett, who converted his garage into a home gym and then built a shed for his woodworking workshop. He’s very happy with both, but he did spend the better part of $40,000 across the two projects.

Neither option is universally better. Match the solution to your actual use case, budget, and site constraints, and either one can serve you well for decades.