Concrete Driveways on Sloping Traralgon Blocks: Getting the Falls Right

A driveway on a sloping Traralgon block succeeds or fails on its falls. Water has to run off the slab and away from the garage, not into it, and the changes in grade at the kerb and the garage door have to suit a car's underside. Get the set-out right and the pour is the easy part. Get it wrong and there's no fixing it without cutting the slab out.

We work in Traralgon most weeks, and a lot of that is in the newer estates: smaller blocks, sloping setbacks and tighter access than the flat blocks we pour on around Sale. The concrete is the same. The thinking before the pour is not.

What makes a sloping block different?

On a flat block, the main job is a gentle fall so rain runs off. On a slope, gravity has already decided where the water wants to go, and the driveway has to work with it. That changes the formwork, the edges, the drainage and sometimes the retaining. It also changes the price: expect a steep driveway to cost 10 to 25 per cent more than the same area on flat ground, because of the extra set-out, edge work and labour.

What if the driveway slopes down toward the garage?

This is the one that causes the most grief. When the garage sits lower than the street, every storm sends the water from the whole driveway straight at the roller door. The fix is designed in, not added later: a grated strip drain across the driveway in front of the garage, connected to the property's stormwater, with the slab falling to it. Where that water can legally go is a Latrobe City Council matter, so the connection gets sorted before the pour, not discovered at inspection.

When the block slopes up from the street, the problem flips. Water runs off the driveway toward the road, which is usually fine, but it has to cross the footpath and the crossover without scouring the edges or pooling at the bottom. We set the falls so it goes where it's meant to.

Why do some cars scrape, and how is it avoided?

Cars scrape where the grade changes sharply: at the kerb, where the crossover meets the driveway, and where the driveway meets the garage slab. On a steep block those transitions are where the design work sits. We set the changes in grade so they're gradual enough for a normal car to roll over, and if you've got a low car, a caravan or a trailer that lives in the garage, tell us at the site visit so we set out for the thing that actually has to get up there.

Which finish grips best on a slope?

On anything with real grade, grip in the wet matters more than looks. A broom finish run across the slope, not down it, gives feet and tyres something to hold on a frosty Valley morning. Exposed aggregate grips well too and hides tyre marks, which is why it's common in the Traralgon estates. The finish to avoid on a slope is anything trowelled smooth, which turns into a slide in a July frost.

What happens under the slab on cut and fill blocks?

A lot of estate blocks around Traralgon were cut on the high side and filled on the low side when the subdivision went in. Cut ground is usually firm. Fill is only as good as the compaction it got, and clay-heavy Valley ground behaves differently wet and dry. So the dig tells us what we're working with, soft spots get dug out and replaced with compacted crushed rock, and the low edge of the slab gets a deeper, thickened edge so it isn't left hanging over ground that settles. A standard residential driveway is 100mm thick. Heavier vehicles or softer ground take it to 125mm.

Getting the concrete there

Tight estate frontages, a neighbour's new driveway on one side and a slope on the other often mean the concrete truck can't reach every corner of the pour. Then a pump truck earns its place, with the minimum hire usually $1,200 to $1,600. We plan where the truck and pump sit at the site visit so pour day runs without anyone driving over your lawn or your neighbour's.

And the crossover

The crossover from the road to your boundary is built to Latrobe City Council's specification, and on a sloping block its levels have to marry up with the driveway above or below it. We pour crossovers across Traralgon and Morwell to council spec, and we've written up the Latrobe City crossover rules separately on the blog.

Get it set out properly

If you've got a sloping block in Traralgon, Morwell, Moe or anywhere around the Latrobe Valley, book a site visit. Nick will stand on the block with you, check where the water goes, look at the grade changes and the access, and the written quote will show the drainage and edge work, not hide it. Qualified, insured, and a workmanship warranty on every driveway. Or give me a call.