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Home / Capabilities / Permeable Concrete Car Parks
Permeable Concrete Car Parks.
The car park and the stormwater system share one surface. Rain passes through the bays into a stone base, so the site's impervious area and its detention can shrink or go.
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Check if permeable concrete suits your site
A few quick questions about your site. You get a straight answer about whether permeable concrete is the right call, including when it isn't, before anyone asks for your details.
Site check · 1 of 4
What is the ground like?
A rough answer is fine. We confirm it on site.
Permcon™ is Australian made. Designed at our Mitcham factory, mixed with Boral Concrete and poured by our own crewsAbout our manufacturingWhat a permeable concrete car park gives you
On most sites the car park is the biggest piece of hard ground. Sealed, every storm on it becomes runoff you have to collect at a grate and pipe away. Pour it in Permcon and the rain goes down through the bays into a stone base, which stores it and lets the ground take it. The bay by the entry stays dry, with no sheet of water crossing the aisle.
That changes the civil design. In a passive design the surface is treated as pervious, so it counts toward permeable area where the scheme sets an impervious cap, and the detention a sealed car park would need can shrink or disappear. See how that fits the whole-site picture for commercial properties.
Our crews place 500 m² and more in a day, in one continuous pour with no joints. The surface carries a P4 slip rating. It comes with a 10-year structural warranty and a design life in excess of 30 years, given a look each month and a sweep a year.
Thickness is the lever
Permcon holds 25+ MPa on every job, and that doesn't change; what varies from job to job is the thickness. The standard slab is 125 mm, and larger car parks go slightly thicker, at 150 mm or 175 mm of Permcon over the base course, because of the size of the vehicles driving on them.
Waste trucks and heavier vehicles get sized from the loading chart, which gives an estimated maximum axle load for each slab thickness. Those two thicknesses sit at an estimated 8.3 t and 11.3 t, and heavier axles get a thicker lane, which we size with your engineer. The chart is calibrated from a Benkelman beam back-analysis for crane loading. Going thicker increases the amount of weight that can go on it.
A car park with no pipes under it
A 2,200 m² hot-springs car park on the Mornington Peninsula sits on free-draining sand, so the cheapest drainage system was already under it. Our Permcon there passes 9,000 mm/hr, and the sand beneath is slower but still quick. The parking field went in with no conventional subsurface drainage across it. Other jobs are on our projects page.
Why choose Permcon™?
Drains where it landsRain goes straight through the bays into a stone base under the pavement, keeping the aisle clear rather than carrying water to a pit.
Less drainage to buildThe stone base is storage your civil engineer can count.
Sized for the vehiclesSame mix on every job, poured thicker where waste trucks and heavier axles run.
One surface, three functionsThe pavement also detains the stormwater and cleans it, and a passive design treats the whole footprint as pervious area.
How a job runs
- Site visitWe look at the soil, the falls, where the water goes now and the heaviest vehicle that will use it. That sets the thickness.
- BaseClean screenings go under the slab, with filter cloth, and an under drain where the ground needs help moving water.
- PourOur own crews place it, up to 500 m² in a day.
- AfterOnce a month, check it's clear of leaves, that it drains after rain and that no sediment is building up. That's most of the maintenance.
Permeable Concrete Car Parks gallery
What engineers, developers and councils ask
Does a permeable concrete car park count as pervious area?
Yes, in a passive design, as the section above explains. Councils word their impervious caps and detention controls differently, though. We put the drainage behaviour in writing for your engineer to submit, and the authority decides what counts.
Can it take a waste truck?
It can, by going thicker on the lane the truck uses. The loading chart in the thickness section gives the estimated axle load for each thickness. Tell us the heaviest vehicle at the site visit and we'll size that lane from it, leaving the other bays at car thickness.
What happens in a big storm?
The surface keeps taking water, because the slab passes far more than any storm delivers. The limit is the base. How much it holds, and how fast the ground or the under-drain empties it, is exactly what the base depth is designed for.
Can we model it in MUSIC?
Yes. Ask us for the node parameters and they'll come with the profile we design for your site. On the treatment side, it removes up to 70 per cent of heavy metals, hydrocarbons, detritus and suspended solids from the water passing through.
What maintenance does a car park need?
Once a month, walk it to check it's clear of leaves and debris and draining properly after rain, and that garden beds aren't washing soil across the bays. Sweep it once a year. Sediment is what clogs a car park, and washing recovers it.
Can permeable concrete carry everyday car park traffic?
Permcon is a 25+ MPa concrete, poured over a base of clean screenings.Bays that need to take heavier vehicles get a thicker slab in that spot, not a different mix.
Does a permeable car park cope with heavy vehicles?
Areas that carry heavier vehicles on a Permcon car park usually get poured thicker than the bays around them, because that's where the heavier axles run. The mix doesn't change: at 125 mm the estimated axle load is 5.8 t, and stepping up to 175 mm lifts that to 11.3 t. Even an axle around 30 t is answered with a thicker slab, not a different pavement. Tell us what's actually going to drive on each part of the car park and we'll set the profile before we pour.
What upkeep does a permeable concrete car park need?
Once a year, sweep it. That's the baseline for a car park like this, on top of a monthly walk-through to check it's clear of leaves, draining after rain and free of visible sediment build-up. Sediment mostly comes from soil off garden beds or leaf litter, so stabilise bare ground upstream and watch for overland flow that's shifted onto the pavement. If a section has been neglected and started to pond, sweep it, blow it off or wash it, as the maintenance guide says. Add it to the same asset schedule as the rest of the car park and it keeps draining.
Does a permeable concrete car park help meet council WSUD conditions?
MUSIC certification is usually the first thing a Queensland council asks about, and Permcon has it. Beyond the certificate, it's a WSUD asset in its own right: it cuts runoff, detains peak flows in the base, and filters what comes off the bays, removing up to 70 per cent of heavy metals, hydrocarbons, detritus and suspended solids. In a passive design the surface can be treated like a grassed area, which shrinks or removes the detention structure a sealed car park would otherwise need. Ask us for the MUSIC parameters and we'll work the numbers through with your civil engineer.
What's the working life of a permeable car park?
We back every Permcon car park with a 10-year structural warranty, and the pavement itself is designed to run in excess of 30 years. The 25+ MPa slab isn't the weak point. Clogging is: sediment off garden beds or exposed soil fills the voids over time and slows the drain. Stop that at the source: keep garden beds stabilised, sweep the surface once a year. A section that does fail structurally gets assessed, cut out and replaced under warranty without touching the rest of the car park.
Will paving around our car park trees kill them?
Tree protection zones are one of the few places a sealed pavement can't go, and Permcon can. Air and water keep reaching the root zone through the voids in the surface, which is why it's accepted where a solid slab wouldn't be. That means you can keep the shade a car park needs, and still count the surface as pervious area. We work to whatever zone the arborist sets.
Where the water goes once it's through the slab
The slab is the fast part: rain passes through Permcon at 8,000 to 10,000 mm/hr. Designing the base takes the real work. It's a course of clean screenings, and a typical car park profile holds between 42 litres and 56 litres per square metre at 85 per cent design capacity, while the ground beneath takes the water at its own pace.
On clay, or where the authority won't allow soakage, we deepen the base and add an under-drain that releases water at a controlled rate. The car park still detains and filters. As it drains, heavy metals, hydrocarbons, detritus and suspended solids are held back in the profile. Permcon is MUSIC certified for councils that want it modelled.
Concrete car parks we've poured
Early Learning Centre, Warwick
A council job in Warwick: light-coloured Ultracon poured around an Early Learning Centre's existing cubby houses, sandstone blocks and garden beds to make a permeable play area.
Permcon Garage Driveway
A grey Permcon driveway runs up to a brown garage door, with a mulched garden bed and timber posts along the side.
Driveway for Residential Units
Ferns and red-leaved planting mark the bend where this dark grey Ultracon driveway curves past shared garages, its edges softened by garden beds.
Housing Unit Car Park
Wheel stops in yellow and black, bays marked in white, a wide aisle: a dark grey Ultracon permeable car park for housing units in front of black-and-white-clad townhouses.
Residential Driveway Project
Split down the middle by a black timber fence, two plain grey permeable parking pads front a contemporary home and finish at garden beds on each side.
Start with someone standing on the site
We design Permcon and our own crews install it. We're based in Mitcham in Melbourne, with teams in every state. After one visit you'll have the slab thickness and base depth in writing, plus the storage they give you.