Yes, you can use recycled concrete aggregate (RCA) for a DIY garden path — and it can be a cost-effective, environmentally friendly choice. However, there are some important things to understand about how RCA behaves differently from virgin aggregate, and how to prepare your path properly so it lasts.
What Is Recycled Concrete Aggregate?
Recycled concrete aggregate is crushed material sourced from demolished concrete structures such as driveways, foundations, and slabs. In New Zealand, it is commonly available from concrete recycling yards, demolition companies, and some landscape suppliers. It typically comes in a range of grades — from fine crusher dust through to 40 mm or larger chunks — and is often sold by the tonne or cubic metre.
RCA is not the same as virgin crushed rock (like AP40 or AP20 basecourse). It tends to be more porous and can absorb more water, which affects how it compacts and drains over time.
Is It Suitable for a Garden Path?
For a loose-laid or compacted garden path (not a structural concrete pour), RCA is generally well suited. It works best when used as:
- A compacted basecourse beneath pavers or stepping stones
- A loose gravel-style path surface on its own
- A fill layer to build up low areas before a path surface is laid
It is not recommended as the aggregate in a structural concrete mix for paths that need to carry vehicle loads or meet specific strength requirements. For those applications, use certified virgin aggregate and follow a proper concrete mix design.
Key Considerations Before You Start
1. Source It Carefully
Not all RCA is equal. Avoid material that contains:
- Asphalt or tar (can leach contaminants)
- Reinforcing steel (trip and injury hazard)
- Plasterboard, timber, or other debris
- Painted concrete that may contain lead (common in pre-1980s buildings)
If you're unsure of the source, ask the supplier for information about where the material came from. WorkSafe NZ has guidance on handling demolition materials safely, particularly around asbestos and lead paint risks in older buildings.
2. Check for Contaminants
Older concrete (pre-1980s) may have been made with materials or coatings that contain hazardous substances. If in doubt, wear gloves and a dust mask when handling, and wash hands thoroughly afterwards.
3. Drainage Is Critical
RCA can hold more moisture than virgin aggregate. Good drainage underneath your path will prevent it from becoming boggy or shifting in wet weather — both common issues in many parts of New Zealand. BRANZ provides useful guidance on ground drainage and moisture management around homes.
4. Compaction Matters
For a stable path, RCA needs to be properly compacted in layers. A plate compactor (available to hire from most tool hire shops) will give far better results than tamping by hand. Aim for layers no deeper than 100 mm before compacting.
How to Lay a Recycled Concrete Aggregate Garden Path
- Mark out your path with stakes and string line.
- Excavate to a depth of 100–150 mm, depending on your intended surface.
- Install edging (timber, steel, or plastic garden edging) to contain the material.
- Lay geotextile fabric on the base to suppress weeds and prevent the aggregate from mixing with the soil below.
- Spread RCA in layers of no more than 100 mm and compact each layer thoroughly.
- Top with a finer grade of RCA or crusher dust for a smoother walking surface if desired.
- Check levels to ensure water drains away from your house foundation — a fall of around 1:100 (1 cm drop per metre) is a good guide.
Do You Need a Building Consent?
A simple garden path is generally exempt from building consent under Schedule 1 of the Building Act 2004. However, if your path is close to a boundary, involves significant earthworks, or connects to a structure, it's worth checking with your local council. Always confirm consent requirements with your council before starting work — rules can vary by region and property.
For more on consent exemptions, visit MBIE Building Performance.
Cost Guide (Approximate)
As a rough guide only, RCA is generally cheaper than virgin aggregate — often significantly so. Prices vary by region and supplier, so get a few quotes. Factor in the cost of geotextile fabric, edging, and plate compactor hire when budgeting.
You can find landscape and concrete supplies at Bunnings, Mitre 10, and PlaceMakers.
When to Call a Professional
While a garden path is a manageable DIY project for most homeowners, consider hiring a qualified concreter or landscaper if:
- Your path is on a steep slope or unstable ground
- You want a poured concrete path (which requires proper mix design, formwork, and finishing)
- The area has poor drainage that may need subsoil drainage work
- You're unsure about ground conditions or contamination
A professional concreter will have access to quality-tested materials and the equipment to compact and finish the job properly. You can find qualified local concreters and landscapers on tradedirectory.co.nz.
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