How Thick Should a Concrete Slab Be for a Shed?
Shed slab thickness depends on your shed’s size and intended use:
Standard Garden Sheds (storage, tools, equipment):
- 100mm thick with SL72 mesh reinforcement
- Suitable for sheds up to 6x3m
- Handles typical storage loads without issues
Workshops & Heavy-Use Sheds (machinery, vehicles):
- 125-150mm thick with SL82 or F72 mesh
- N32 concrete grade for impact resistance
- Built for workbenches, heavy equipment, and point loads
Large Storage & Industrial Sheds:
- 150mm+ thickness with engineer-designed reinforcement
- Required for spans over 6x6m or reactive clay soils
- Prevents cracking and settling on challenging sites
Undersized shed slabs crack under loads, while properly specified slabs provide decades of trouble-free service. Always match slab thickness to your shed’s purpose and Newcastle’s ground conditions.
Types of Shed Slabs We Install in Newcastle
Not all shed slabs are created equal. What works for a basic garden shed won’t cut it for a workshop where you’re running machinery or storing heavy equipment. We match the slab specs to how you’re actually going to use your shed.
Garden Shed Slabs
These are your standard storage sheds for lawn mowers, garden tools, bikes, and general storage. Garden shed slabs run 100mm thick with SL72 mesh and N25 concrete—more than enough for lightweight storage and standard shed loads in Newcastle suburbs.
Workshop & Tradesman Slabs
If you’re bolting down workbenches, running power tools, or storing machinery, you need something tougher. Workshop slabs go 125mm thick minimum with SL82 or F72 mesh and N32 concrete. The extra thickness handles point loads from heavy equipment and resists impacts.
Large Storage & Machinery Sheds
These are the big ones—6x6m and up for boats, caravans, or farm equipment. Large shed slabs need engineer-designed reinforcement, typically 150mm thick or more. On reactive clay sites around Maitland, we specify thicker edges and additional reinforcement to handle ground movement.
Carport & Vehicle Storage Slabs
Storing a car, ute, or trailer? Vehicle storage slabs handle rolling loads and vehicle weight at 125-150mm with appropriate reinforcement. The surface needs to be smooth enough for easy vehicle movement but textured enough so you’re not sliding around when it’s wet.
Shed Slab Construction Specifications
Getting the specs right matters because once your shed’s up, you can’t go back and fix a slab that’s too thin or poorly reinforced.
Standard Garden Shed Requirements
For garden sheds up to 6x3m, we pour 100 mm-thick slabs with SL72 reinforcing mesh and N25 concrete. The mesh sits in the middle third of the slab (around 40-50mm from the bottom) to control cracking. We include a compacted 75mm crusher dust base and a damp-proof membrane underneath to stop moisture rising through the concrete.
Workshop & Heavy-Use Specifications
Workshops and heavy-use sheds need 125-150mm thickness with SL82 or F72 mesh reinforcement. We use N32 concrete grade—it’s tougher and handles impacts better when you’re dropping tools or moving heavy equipment around. Thickened edges (200mm deep) around the perimeter give extra support where the shed frame sits, and anchor bolts go through.
Large Shed Engineering Requirements
Anything over 6x6m or on reactive clay soils needs proper engineering. We’re talking 150mm+ thickness with custom reinforcement design based on soil tests and load calculations. On problem sites around Newcastle and Maitland, we add extra steel, deeper edge beams, and sometimes pier supports underneath to deal with ground movement.
Our Shed Slab Preparation & Construction Process
We don’t just turn up and pour concrete. Shed slabs need precision. Our process includes;
Site Assessment & Preparation: We start by confirming exact dimensions with your shed supplier—length, width, and anchor bolt positions. Then we assess your site for drainage, existing levels, and soil conditions. If there’s existing grass, pavers, or old concrete, we excavate that out along with 150-200mm of topsoil to reach solid ground.
Base Compaction & Formwork: We lay 75-100mm of compacted crusher dust as the base layer—this stops ground moisture and gives us a stable platform. The base gets compacted in layers with a plate compactor until it’s rock solid. Then we set up timber formwork at the exact shed dimensions, checking it’s perfectly square and level.
Reinforcement & Concrete Pouring: Reinforcing mesh goes in on plastic bar chairs, so it sits in the middle third of the slab. We install anchor bolts (if your shed needs them) at precise locations matching the shed frame. Then we pour N25 or N32 concrete depending on the shed type, screed it level, and finish with a smooth steel trowel.
Anchor Bolts & Finishing: Anchor bolts get positioned while the concrete’s still workable—we use the shed manufacturer’s specifications so they line up perfectly with the frame. After screeding, we add control joints every 3m to control where cracks form. The slab then cures for a minimum of 7 days before your shed installation.
Why Choose Concrete for Your Newcastle Shed Base
Durability & Weather Resistance: Concrete doesn’t rot, warp, or deteriorate like timber in Newcastle’s humid coastal climate. A properly poured concrete shed base lasts 30-40 years with zero maintenance—timber bearers start rotting within 5-10 years, especially near the coast.
Protection from Moisture & Pests: Concrete creates a solid barrier between ground moisture and your shed floor. No rising damp, no termites eating timber supports, no rust from metal on wet ground. Your tools and equipment stay dry and protected year-round.
Level Foundation Benefits: A level concrete slab means shed doors open properly, shelving sits straight, and no water pools when it rains. Newcastle’s reactive clay soils move constantly—properly engineered concrete with reinforcement handles that movement without your shed twisting.
Shed Slab Costs & Investment in Newcastle
Pricing Factors for Shed Slabs: Slab dimensions are the biggest cost factor—more concrete and reinforcement mean a higher price. Thickness matters too—125mm slabs cost more than 100mm. Site access affects pricing—tight spaces need wheelbarrows instead of concrete pumps, which takes longer.
Common Shed Slab Sizes & Costs: Small garden sheds (3x3m) are the most affordable option. Medium sheds (6x3m) suit most workshop needs. Large sheds (6x6m to 9x6m) cost more but give serious storage space. We provide free quotes so you know exactly what you’re paying upfront.
Value of Proper Construction: A quality shed slab protects your investment. Cheap shortcuts lead to cracked slabs, settling, and eventually shed replacement costs. Spending properly upfront saves thousands later—failed slabs cost more to fix than doing it right the first time with proper specifications.
Frequently Asked Questions About Shed Slabs Newcastle
How long does it take to pour a shed slab?
We typically complete shed slabs in one day—site prep and formwork in the morning, concrete pour in the afternoon. The slab needs a minimum of 7 days to cure before your shed installation. Total timeline from booking to shed-ready is usually 10-14 days, depending on the weather.
Do I need council approval for a shed slab?
Most garden sheds under 10m² don’t need council approval in Newcastle, but larger sheds or workshops might. We recommend checking with Newcastle Council before starting. We can advise on what’s typically required based on your shed size and location.
Can you pour a shed slab on sloping ground?
Yes, we handle sloped sites all the time around Newcastle. We excavate and level the site, then build up the low side with compacted fill. On steep slopes, we might recommend a stepped slab or retaining wall to manage the grade properly.
What's the difference between N25 and N32 concrete?
N25 concrete suits standard garden sheds and light storage. N32 is stronger—we use it for workshops and heavy-use sheds where you’re moving machinery or dropping heavy tools. The higher number means higher compressive strength and better impact resistance.
How do you coordinate with shed suppliers?
We contact your shed supplier directly to confirm the exact dimensions and anchor bolt positions before we start. This ensures the slab matches your shed perfectly when it arrives. We’ve worked with most major shed companies servicing Newcastle.
What happens if my shed slab cracks?
Small hairline cracks are normal in concrete—that’s why we include control joints. Structural cracks from settlement or undersized slabs are different. Our properly engineered and reinforced shed slabs don’t develop structural cracks because we account for Newcastle’s soil conditions from the start.
Can I pour a shed slab myself?
You can, but getting it level, square, and properly reinforced is harder than it looks. Most DIY shed slabs we’re called to fix cost more to repair than hiring us initially. If your shed’s worth doing, it’s worth doing with proper equipment and experience.
Ready for a Rock-Solid Shed Foundation?
Planning your shed installation? We coordinate with your shed supplier to deliver perfectly sized, level concrete slabs on time. Fast turnaround to meet your shed delivery schedule.
Whether you need a simple garden shed base or a heavy-duty workshop slab, we’ve poured hundreds of shed slabs across Newcastle, Maitland, and Lake Macquarie.
Get Your Free Shed Slab Quote
Call 0482085820 or complete our quick quote form.
Service Areas: Newcastle, Maitland, Lake Macquarie, Hunter Valley
