Understanding Jointly Owned Access Lots and Underground Stormwater Design
Jointly Owned Access Lots (JOALs) are now a defining feature of modern New Zealand subdivisions. As developments become more compact and land is used more efficiently, shared driveways and accessways are increasingly common. While most people see a JOAL as simply a shared driveway, under New Zealand property law it is much more than that — and it has major implications for stormwater tank design and installation.
For developers, engineers, and planners, understanding how JOALs work is essential to ensuring that underground stormwater infrastructure is compliant, durable, and fit for purpose.
What Is a JOAL Under New Zealand Property Law?
A JOAL, or Jointly Owned Access Lot, is a legal land title used where two or more properties share a private accessway. Instead of being owned and maintained by the local council like a public road, a JOAL is co-owned by all properties that use it.
Each owner holds an undivided share in the access lot, giving them an equal legal right to use it. JOALs are governed by the Property Law Act 2007, which gives property owners rights similar to an easement, ensuring permanent legal access to their land.
JOALs are commonly used in:
They are particularly common where more than four lots need access from a single street.
Why JOALs Are Critical to Stormwater Design
Because JOALs are:
They are some of the most structurally and legally sensitive land in a subdivision.
Stormwater infrastructure located beneath or adjacent to a JOAL must cope with:
In addition, JOALs often sit at the lowest point of a site, meaning they collect runoff from roofs, driveways, and paved areas. This makes them the natural location for underground stormwater detention tanks and drainage systems.
Stormwater Tank Requirements for JOAL Developments
Most councils now require new developments to manage stormwater on site to reduce flooding and protect downstream infrastructure. This typically means installing underground stormwater tanks to store and slowly release runoff during heavy rainfall.
When stormwater tanks are installed beneath a JOAL, they must be designed to handle:
Standard lawn grade tank solutions are not suitable for this environment. A failure beneath a JOAL can disrupt access for every property on the title and create complex legal and financial issues for owners.
Why Traffic-Rated Stormwater Tanks Are Essential Under JOALs
JOALs are not landscaped areas — they are working driveways that must remain safe and functional for decades. Stormwater tank systems must be engineered for:
If a tank deforms, cracks, or settles, it can lead to:
For this reason, councils and engineers increasingly specify traffic-rated stormwater detention systems for JOAL applications.
APD Stormwater Tanks for JOAL Installations
APD designs engineered tank solutions and installation detail specifically for high-load environments such as JOALs, shared driveways, and commercial accessways.
Our systems can be engineered to suit:
Our StormLite®, StormSlab® and StormLite³ solutions are commonly used in JOAL developments because they are:
This makes them ideal for installations beneath concrete driveways, shared accessways, and high-use areas.
Protecting Property Titles and Long-Term Compliance
Because JOALs are governed by the Property Law Act, any failure in infrastructure beneath them can affect every property owner. Restricted access, flooding, or pavement collapse can create:
Installing the right stormwater system from the outset protects:
Designing Stormwater Systems That Work With JOALs
JOALs allow higher-density housing and smarter land use — but they also demand higher engineering standards. Stormwater tanks installed beneath shared accessways must be built to handle more than just water; they must support vehicles, structures, and legal access rights for decades to come.
APD’s stormwater tank systems are engineered to meet the structural, hydraulic, and legal realities of JOAL developments. (All our tanks are made to the same benchmark, whether it’s for the JOAL or standard installation in the garden or driveway, the same process in manufacturing is followed ) , ensuring compliant, durable, and low-risk outcomes for modern subdivisions.
If your project includes a JOAL, make sure your stormwater system is designed for what it really is — a critical piece of shared infrastructure beneath a shared legal title.
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