Here’s the part of your shed you’ll never see — and it’s the part that decides how long the thing lasts, how much it really costs, and whether it’s still dead-level in twenty years.
The footings and the slab.
Nobody photographs the footings. There’s no “before and after” shot of a hole in the ground. Which is exactly why it’s the first place a cheap quote quietly cuts corners. Out of sight, out of mind — right up until it isn’t.
So let’s dig into it. Literally.
There are two ways to stand a shed up
Slab last. The frame goes up first, with the steel columns sunk straight into holes in the ground. Then the concrete floor gets poured around everything, afterwards.
Slab first. You pour the concrete slab, then build on top of it — the same way a house is built.
They sound like small technical choices. They’re not. They lead to very different holes, very different costs, and very different sheds.
The hidden cost of “concrete later”
A lot of kit sheds are designed for the slab-last method. Here’s what that actually involves once it’s on your block.
Because the columns carry the whole building through the ground, the footings have to go deep — often 1.2 to 1.8 metres. That’s not a shovel job. That usually means hiring an auger to bore holes 450 to 800mm wide, then filling them with a surprising amount of concrete.
So before you’ve even poured the floor, you’ve paid for machinery hire, extra excavation and a lot more concrete than you’d expect. All of it underground, where you’ll never see the money you spent.
Then there’s the longer-term problem. When you set structural steel into the ground and pack wet concrete around it, that steel is far more prone to corroding over the years. It’s buried, it’s hard to inspect, and moisture finds a way. You won’t notice for a long time — and then you will.
Here’s the irony that catches people out: a kit is designed to be the cheapest thing to buy, not the cheapest thing to build. The kit is only about two-thirds of your total spend. So the “bargain” shed with posts in the ground can quietly cost you thousands more once the auger and the concrete truck have been and gone.
The ground itself has a say
Bits of the Fleurieu sit on reactive clay — soil that swells when it’s wet and shrinks when it’s dry. Left unaccounted for, that movement is what cracks slabs and racks door frames out of square.
That’s why a footing and slab shouldn’t be a guess or an off-the-shelf number. The site gets classified, and the slab and footings are engineered to that soil, to the relevant Australian Standard, with the right reinforcement and properly compacted ground underneath. It’s the unglamorous engineering that keeps everything above it straight and true.
If a quote doesn’t mention the soil at all, that’s worth a second look. The ground doesn’t care how good the shed is.
How we do it: build it like a house
We use the slab-first method, because it’s better on almost every count.
We pour the concrete slab first, engineered to your site. We build the frame on top and sit it on hot-dip galvanised footing brackets that are guaranteed not to corrode against the concrete — no steel buried in the dirt. Then we use foam insulation to close any gaps where the frame meets the slab.
And because the structure isn’t carrying itself through the ground, the footings only need to be around 400mm deep in most cases. No 1.8-metre holes. No auger hire. No giant volumes of underground concrete. A cleaner build, a better-protected structure, and — more often than not — a lower total cost, not a higher one.
Same shed on top. Completely different story underneath.
What to check before you sign
You don’t need to be an engineer to ask the right things. Before you commit to any shed, ask:
Are you pouring the slab first, or last?
This one answer tells you most of what you need to know.
How deep are the footings, and how wide?
Deep, wide holes mean auger hire and a lot of concrete you might not have budgeted for.
How is the steel protected where it meets the concrete?
“In the ground” and “on galvanised brackets” are very different answers.
Has the slab been designed to my soil?
If nobody’s mentioned the ground, nobody’s engineered for it.
The bottom line
The shed you see is the easy part. The bit underneath — the footings, the slab, how the steel is protected and how the ground was accounted for — is where a build is quietly made good or quietly made cheap.
It’s also the one thing you can’t fix later without pulling the whole lot up. So it’s worth getting right the first time.
Building on the Fleurieu and want to know what’s actually going under your shed? Ask us — we’re always happy to talk through it before a single hole gets dug.
