What Thickness Should a Garage Slab Be?

Thickness recommendations:
- Standard residential garages (cars, SUVs): 100mm minimum with steel mesh reinforcement
- Heavy-duty use (4WDs, trailers, workshop equipment): 125mm with upgraded reinforcement
- Commercial or industrial applications: 150mm+, depending on load requirements
All garage slabs should include a properly compacted 100mm crushed rock base and N32 grade concrete minimum to ensure long-term performance in Hobart’s climate conditions. The base is just as important as the thickness—without proper base preparation, even a thick slab can settle and crack over time.

Types of Garage Slabs for Hobart Properties

Hobart-Specific Requirements and Compliance
Council Approval and Building Permits: Garage slab construction may require building approval in Hobart. Council application takes 4-6 weeks. Setback and heritage overlay considerations apply in older suburbs.
Tasmanian Building Standards Compliance: Compliance with the National Construction Code and Australian Standard AS 2870 is required. Structural adequacy for Tasmania’s conditions. BAL requirements for at-risk areas apply.
Site-Specific Considerations: Managing sloped terrain common in Mount Nelson and West Hobart. Retaining walls for cut-and-fill sites. Drainage solutions for water flow issues are required.

Performance Features for Tasmania's Climate
Weather Resistance and Durability: Frost-resistant concrete mixes for Hobart’s winter conditions. Temperature fluctuation tolerance from -2°C to 25°C annually. Moisture barrier protection against Tasmania’s 600mm+ annual rainfall.
Drainage and Water Management: Integrated at a 1:100 minimum to prevent water pooling. Proper grading away from the garage entrance. Connection to stormwater systems where required. Solutions for natural water flow.
Load-Bearing and Structural Performance: Vehicle weight capacity of 2,500kg+ per standard car. Support for daily vehicle movement and turning. Resistance to impact from dropped tools. Stable base for garage structure.
Long-Term Maintenance and Protection: Sealing options for dust-proofing and stain resistance. Oil and chemical spill resistance. Easy cleaning with a broom or a hose. Minimal maintenance over a 40+ year lifespan.
Garage Slab Construction Process in Hobart
Site Preparation and Assessment: Initial site measurement and level assessment. Evaluation of slope and drainage requirements. Identification of underground services. Soil testing for reactive clay. Access assessment for concrete trucks.
Base Preparation and Excavation: Excavation to 150-200mm depth below final slab level. Installation of 100mm crushed rock base. Proper compaction prevents settlement. Vapour barrier installation prevents ground moisture issues.
Formwork and Reinforcement: Timber or steel formwork installed to slab dimensions. Edge thickening 300mm deep for support. SL82 mesh placement. Falls set at 1:100 minimum toward the garage door.
Concrete Pouring and Finishing: N32 grade concrete minimum for vehicle loads. Continuous pour avoids cold joints. Professional screeding for a level surface. Choice of trowel smooth or broom texture finish.
Typical project timeline: 5-10 days, including curing. Weather plays a role—we avoid pouring in forecast frost or extreme heat because that affects concrete performance. Hobart City Council inspections may be required depending on your specific project.
Frequently Asked Questions About Garage Slabs in Hobart
We recommend waiting a minimum of 7 days before driving on your new garage slab. The concrete reaches about 70% of its strength in the first week, but it continues curing for up to 28 days to reach full strength. We know that’s a long time to wait, but rushing it can cause surface damage and cracking that you’ll be dealing with for years. If you absolutely need to use the garage sooner, talk to us about accelerated curing options, but honestly, patience pays off here.
It depends on what you’re building. If you’re constructing a new garage or doing major renovations, you’ll likely need council approval from Hobart City Council. For a simple slab replacement in an existing garage footprint, you might not. We handle the council liaison for our clients because the approval process can be confusing, and getting it wrong delays your project by weeks. Typical approval takes 4-6 weeks once submitted.
A double garage slab costs roughly 1.5 to 2 times more than a single garage slab, not double the price as you might expect. That’s because much of the cost is in mobilisation, site setup, and base preparation, which don’t scale linearly with size. We provide detailed quotes based on your specific site conditions, access, and any complications like slope or poor soil. Every property is different, so blanket pricing doesn’t really work.
Not if it’s built properly. We use frost-resistant concrete mixes and proper reinforcement specifically because Hobart gets winter frosts. Cracking happens when slabs are poorly reinforced, poured too thin, or installed without adequate base preparation. The temperature fluctuations we get in Tasmania—from winter frosts to summer heat—require proper engineering. That’s why we include SL82 mesh reinforcement and edge thickening as standard, not optional extras.
Yes, but we’re selective about the conditions. We avoid pouring when frost is forecast because it affects how the concrete cures and can weaken the surface. Winter pours are definitely possible on mild days, and sometimes we use additives to help with cold-weather curing. The alternative is waiting until spring, which might not suit your timeline. We’ll give you honest advice about weather windows rather than rushing a pour that could cause problems later.
SL82 mesh is our standard reinforcement for residential garage slabs—it’s a welded wire mesh that provides good tensile strength for typical vehicle loads. Steel reinforcement bars (rebar) are used for heavier-duty applications or when you’ve got specific engineering requirements, like spanning over poor soil or handling commercial vehicle weights. For most homeowners with standard cars and SUVs, mesh does the job perfectly fine and costs less than bar reinforcement.
We guarantee our workmanship, which means if problems arise from poor construction on our part, we fix them. What we can’t guarantee is ground movement from issues outside our control—like major landslips, tree roots growing under the slab years later, or undisclosed underground issues. That’s why site assessment and proper base preparation are so important up front. We build these slabs to last 40+ years based on doing everything right from excavation through to final finishing.
Get Your Free Garage Slab Quote Today
Professional garage slab construction throughout Greater Hobart. We deliver level, reinforced concrete slabs built specifically for Tasmania’s climate conditions—engineered to handle vehicle loads, resist moisture, and last 40+ years without ongoing repairs.
Ready to start your garage project? Call now for expert advice and obligation-free pricing. Our team provides honest recommendations based on your specific property conditions and budget.
Phone: 0361706070
Email: info@concretehobart.com.au
Business Hours: Monday-Friday 7 am-5 pm, Saturday 8 am-12 pm
Service Areas: Greater Hobart, including Sandy Bay, Mount Nelson, Battery Point, South Hobart, West Hobart

