Permcon solves site coverage limits

The government has passed the Building and Construction (Small Standalone Dwellings) Amendment Bill, enabling simple detached dwellings of up to 70m² to be constructed without a building consent from early 2026. In parallel, a proposed National Environmental Standard (NES) is intended to remove the need for resource consent for one minor residential unit per site in relevant zones.

Site coverage rules remain

Despite these changes, site coverage requirements still apply. These rules – outlined in District Plans – vary by council and zone but typically allow between 40% and 75% site coverage, with a common limit of around 70% for impermeable surfaces in urban areas. Historically, buildings have been permitted to account for between 30% and 50% of site coverage.

Under the proposed NES, allowable building coverage would increase to 50%. However, there is no proposed change to the overall cap on impermeable surfaces. This means that if buildings take up most or all of the permitted impermeable area, driveways and other hard surfaces may need to be permeable to remain compliant.

Permcon NZ director Stuart Girvan says permeable concrete can help unlock development potential.

“Using Permcon permeable concrete, we can convert a significant percentage of a property’s hard surfaces into permeable areas, allowing homeowners the flexibility to add an MRU while still meeting their local council’s District Plan standards.”

Girvan adds that landscapers should make sure to stay up to speed with the incoming regulations, and any local ones, that might prove useful when discussing requirements with clients.

“Many councils also require minimum areas of a developed site to be green and, if there are no other options, installing artificial grass over Permcon permeable concrete can satisfy this requirement,” said Girvan.

Helping hit sustainability targets

In addition to Permcon’s inherent environmental benefits, the company’s latest product – Permcon CarbonLow – can be specified and installed in exactly the same way as the standard Permcon mix, with lower carbon content.  Designed to reduce embodied carbon by up to 62.2%, Permcon CarbonLow™ is a Toitū certified, low-carbon version of industry-proven permeable concrete, delivering the same strength, durability and permeability customers expect.

Why use Permcon?

Permcon permeable concrete produces a hardwearing, pervious surface that allows stormwater to pass through the top course and into the open grade basecourse beneath. This allows stormwater to replenish the natural ground aquifer or be discharged to the stormwater network via under drains in a measured and controlled manner, reducing the peak flows of a storm event.

As such, permeable concrete pavements help reduce street flooding, improve the health of receiving streams and rivers by filtering debris and pollutants from the stormwater, and cool water as it infiltrates the permeable base system.