What Is Deep Soil? Why It's More Than Just Garden Area

If you've started preparing a Development Application (DA), you've probably come across the term deep soil.

For many homeowners, it's confusing.

"Isn't deep soil just the lawn?"

"Does my garden count as deep soil?"

"Can paving, decking or artificial turf be included?"

The short answer is no. Deep soil is a specific planning requirement that plays an important role in many residential developments across New South Wales.

What Is Deep Soil?

Deep soil refers to areas of natural ground that are free from buildings, basements and significant structures below the surface.

These areas allow trees and large vegetation to establish healthy root systems, absorb stormwater naturally and contribute to the long-term environmental performance of a site.

Unlike general landscaping, deep soil is about what lies beneath the surface, not simply what you can see from above.

Why Do Councils Require Deep Soil?

Many councils include deep soil requirements within their Development Control Plans (DCPs).

The objective is to ensure developments continue to provide:

• Healthy canopy trees

• Space for deep-rooted vegetation

• Natural infiltration of stormwater

• Improved biodiversity

• Reduced urban heat

• Higher quality residential landscapes

As urban development becomes denser, protecting genuine deep soil areas has become increasingly important.

Deep Soil Is Not the Same as Landscaped Area

This is one of the most common misunderstandings during the Development Application process.

A site may contain extensive landscaping but very little deep soil.

For example, the following areas are not usually considered deep soil:

• Concrete paving

• Driveways

• Suspended slabs

• Basement roofs

• Artificial turf

• Raised planter boxes

• Swimming pools

• Decking built over structural slabs

While some of these areas may still contribute to the overall landscape design, they generally do not satisfy deep soil requirements.

Always refer to your local council's planning controls, as definitions and requirements can vary.

Why Deep Soil Matters During a Development Application

Councils assess deep soil because it directly influences the long-term performance of the landscape.

Without sufficient deep soil, it becomes difficult for larger trees to establish and thrive.

This can affect:

• Tree canopy coverage

• Stormwater infiltration

• Soil health

• Biodiversity

• Residential amenity

• The visual character of a neighbourhood

For this reason, councils often require applicants to demonstrate that minimum deep soil requirements have been achieved before granting development consent.

Every Council Is Different

One of the challenges with deep soil is that there is no single rule that applies across every council area.

Each local council may have different requirements relating to:

• Minimum deep soil percentages

• Minimum dimensions

• Location on the site

• Relationship to tree planting

• Species selection

• Environmental constraints

Understanding these requirements early in the design process can prevent significant redesign later.

Why Landscape Architects Calculate Deep Soil

Deep soil calculations are often coordinated by the landscape architect as part of the Development Application documentation.

Rather than simply measuring leftover garden space, the landscape architect considers:

• Existing site conditions

• Proposed buildings

• Retaining walls

• Swimming pools

• Paving

• Tree planting opportunities

• Council planning controls

• Long-term landscape performance

This ensures the landscape plan responds to both the architectural design and the planning requirements.

Common Design Mistakes

Some of the most common issues we see include:

• Oversized pool surrounds reducing deep soil.

• Retaining walls fragmenting planting areas.

• Locating large trees over underground structures.

• Assuming all landscaped areas count as deep soil.

• Leaving deep soil calculations until the end of the design process.

These issues often result in unnecessary redesign during the Development Application assessment.

How Place Supply Can Help

Place Supply provides documentation-focused landscape architecture consulting for residential Development Applications throughout New South Wales.

We prepare landscape plans that coordinate deep soil areas with planting, site planning and council requirements from the outset.

Our services include:

• Development Application landscape plans

• Deep soil calculations

• Landscape compliance assessments

• Swimming pool landscape documentation

• Existing and proposed landscape plans

• Planting schedules

• Council planning support

• Consultant coordination

By considering deep soil early, we help create practical landscape solutions that satisfy planning requirements while supporting high-quality outdoor spaces.

Learn more about our consulting services at https://www.placesupply.com.au/consulting.

Final Thoughts

Deep soil is much more than a planning calculation.

It's one of the key elements that allows landscapes to mature, support healthy tree growth and contribute to more sustainable neighbourhoods.

If you're preparing a Development Application, understanding the difference between deep soil and landscaped area can help avoid unnecessary redesign and improve the quality of your proposal.

When considered early in the design process, deep soil becomes more than just a compliance requirement—it becomes the foundation of a successful landscape.