Choosing a shed foundation isn’t glamorous but it’s the decision that determines whether your shed is still standing properly in twenty years. Most shed problems I’ve seen in three decades of building, buying, and helping mates set theirs up trace back to foundation choice or foundation execution.

The three real options for a backyard shed in Australia are concrete slab, steel pier system, and compacted gravel pad. Each has a place. Each has soil and climate conditions where it’s clearly the right answer.

Concrete slab is the most common choice and the most expensive. The benefits are real: stable, dry interior, easy to clean, can take heavy equipment, and you can fix walls directly without secondary framing. The downsides are cost, the time to cure properly before erecting the shed, and the fact that once it’s there, it’s there. Council approval is generally needed and the slab itself often triggers the requirement.

Steel pier or stump systems work well on sloped sites, in areas with reactive clay soil, and where you want to avoid the cost or paperwork of a slab. The piers can usually be installed faster and the shed can sit slightly above ground level which helps with flooding risk in some areas. The trade-off is that you need to seal the floor properly and you’ll be running services up through the floor rather than chasing them through a slab.

Compacted gravel pad is the cheapest option and works for smaller sheds where the structural loads are light. It’s not appropriate for anything that’s going to store heavy equipment, vehicles, or workshop machinery. It’s not appropriate in areas where termites are a serious concern unless you’ve got proper barriers in place.

Soil considerations matter. Reactive clay (much of Sydney, parts of Melbourne, large slabs of regional NSW) wants either a properly engineered slab or piers. Sandy soils are easy. Anything with significant tree roots needs careful planning. If you’re not sure what your soil is, dig a hole and look at it. If you’re really not sure, get a soil report.

Drainage is the under-discussed half of foundation work. A slab on a site that doesn’t drain properly will pool water against the shed walls. Piers in a low spot collect water around their bases. The few hours spent thinking about where water actually goes during heavy rain is the best foundation investment you can make.

Council requirements vary widely by state and council. Some councils have a size threshold below which you don’t need approval. Others require approval for any structure with a slab. Check your local council before you commit to a foundation type, because the foundation choice can determine whether you need DA approval at all.

For most Australian backyards in 2026, my honest recommendation is concrete slab for sheds 4x3m or larger, especially if you’ll have any heavy equipment. Pier systems are the right answer on sloped or reactive sites. Gravel pads work for smaller garden sheds where you just need a clean dry floor for storage.