Permeable concrete experts.

No. Our standard driveway is a 125 mm slab, and when a job carries more weight we make it thicker rather than change the mix, because the strength is the same on every pour. The surface carries a P4 slip rating, which matters on a sloping driveway after a June downpour.

It can, if the ground around it is allowed to wash onto it. Seed or plant the bare ground and most of the problem goes away. The rest is a monthly look and a yearly sweep, which the maintenance answer spells out.

Houses are only part of it. We also pour council footpaths, shared paths, commercial car parks and sports courts. On the bigger commercial sites our crews place up to 500 m² a day.

Far from it: over 100,000 m² of it has gone down since we started. Stormwater engineers can model it because Permcon is MUSIC certified, and in Queensland that's a big factor when a council submission lands on someone's desk. Behind the product sit ISO 9001, ISO 14001, ISO 45001 and our Master Builders Victoria membership.

Permcon is our own permeable concrete, and we still make it and lay it in-house. It goes down as a single continuous slab, with no joints, over a base of clean screenings. Up top, that's a pavement. Underneath, it's stormwater detention that treats what it holds: up to 70 per cent of the heavy metals, hydrocarbons, detritus and suspended solids come out on the way through. From the base, water soaks into the ground or leaves through an under-drain at a controlled rate.

Rain drains down through the slab instead of running off the surface. Of the slab's volume, 20 to 25 per cent is connected void, and water passes through it at 8,000 to 10,000 mm/hr. The base of clean screenings underneath takes it from there. Each 100 mm of that base holds 28 litres per square metre at 85 per cent design capacity, and gives it up slowly rather than all at once.

Yes, and nothing about the mix changes to let it. Every slab we pour is 25+ MPa, and what carries a heavier axle is depth. Our loading chart, a rigid-slab estimate rather than a field measurement, gives the standard slab an estimated 5.8 t per axle and a 175 mm slab 11.3 t, and the figure keeps rising with thickness from there. We've put Permcon under a bus stop on a main road and through the internal roads of caravan parks. Tell us what's going to drive on it, and we'll set the thickness to suit.

Mostly, it's who's standing on site. We make Permcon and lay it ourselves, so the estimator who specifies your slab and base works for the same company as the crew holding the screed. Strength doesn't move between jobs. No-fines concrete is a different thing: a lower-strength product that shouldn't be used where Permcon goes.

Mostly a monthly walk-over. Check that leaves and debris are off it, that it drained after the last rain, that no sediment is sitting on the surface and that the landscaping upstream hasn't changed. Sweep it or wash it when that walk says to. Once a year it gets a sweep regardless, along with a look into the voids for moss or organic build-up. If a new garden bed or regraded lawn is sending extra water or soil across the slab, redirect the flow at its source.

More than 30 years is the design life. Every job carries a 10-year structural warranty, and if the slab fails structurally we assess the area and remove and replace it as required; terms and conditions apply.

Driveways, footpaths, shared paths and car parks, mostly, with sports courts as well. Tree protection zones suit it too, because a street tree's roots keep getting water and air through the voids instead of sitting under a sealed cap. We're always happy to look and review and go through it with a client.

Homeowners and builders ring us for house jobs, and we deal with them direct. Civil contractors, developers, councils and government bodies bring the bigger work, which usually means sitting down with a stormwater engineer so the screenings base is sized to what their design has to hold. Engineers can ask us for the modelling parameters. Our teams are set up in every state.