Building a brick barbecue is a satisfying weekend project that adds real value to your outdoor living space. With the right materials, a bit of patience, and careful planning, most capable DIYers can construct a solid, long-lasting BBQ that will handle years of summer cooking. No building consent is typically required for a small freestanding garden barbecue, but always confirm with your local council before you start.
Planning Your Brick Barbecue
Before you lay a single brick, spend time on your design. Decide on:
- Size: A common starter size is around 900 mm wide × 600 mm deep internally, which comfortably fits a standard cooking grate.
- Height: A comfortable cooking height is roughly 900–1000 mm from ground level to the top of the firebox opening.
- Location: Choose a flat, stable area away from fences, overhanging trees, and your home's eaves. Check your local council's rules on open fires and outdoor cooking structures.
- Orientation: Position the opening away from the prevailing wind to help control airflow and smoke direction.
Sketch your design on paper first, counting brick courses and marking where your grate support ledges will sit.
Materials You'll Need
| Item | Notes |
|---|---|
| Firebricks | Use for the firebox interior — they withstand high heat |
| Standard clay bricks | For the outer structure and base |
| Refractory (fire) mortar | Essential for the firebox; standard mortar cracks under heat |
| General-purpose mortar | For outer brickwork (cement, sand, lime mix) |
| Concrete | For the footing slab |
| Cooking grate | Stainless steel is best for longevity |
| Steel angle iron or flat bar | For grate support ledges |
| Builders' sand and cement | Standard mix for footings and outer work |
| DPC (damp-proof course) strip | Optional but good practice at base level |
You'll find bricks, mortar, and tools at Bunnings, Mitre 10, or PlaceMakers. Always buy firebricks and refractory mortar specifically — do not substitute standard mortar inside the firebox.
Preparing the Footing
A solid footing is critical. A brick barbecue is heavy, and without a proper base it will settle and crack.
- Excavate to at least 150 mm depth over the full footprint of your BBQ, plus 100 mm on each side.
- Compact the subbase well.
- Pour a concrete slab at least 100 mm thick. In softer or clay-heavy NZ soils, go 150 mm.
- Allow the concrete to cure for a minimum of 3 days before laying bricks — ideally 7 days.
Keep the slab level; use a spirit level and screed board to check.
Laying the Brickwork
Outer Structure
- Mix your mortar to a firm, workable consistency (roughly 4 parts sand : 1 part cement, with a small amount of lime for workability).
- Lay bricks in running bond (staggered joints) for maximum strength.
- Keep mortar joints consistent at around 10 mm.
- Check for level and plumb every two or three courses using a spirit level.
- Build up the two side walls and back wall, leaving the front open for access.
Firebox Interior
- Line the inside of the firebox with firebricks laid in refractory mortar.
- Firebricks can be laid flat (stretcher bond) or on edge depending on your design.
- Leave the refractory mortar joints slightly thinner — around 6–8 mm — for a tight, heat-resistant finish.
- Allow refractory mortar to cure fully before the first fire (check the manufacturer's instructions — typically 24–48 hours minimum, then cure slowly with small fires first).
Installing the Cooking Grate Support
This is the detail that separates a functional BBQ from a frustrating one. There are two reliable methods:
Method 1 — Recessed Brick Corbels
As you build up the side walls, step two or three bricks inward (corbel them) at your desired grate height. These protruding brick ledges support the grate directly. This is the simplest approach and requires no metalwork.
- Corbel bricks should protrude at least 50 mm into the firebox opening.
- Use this method at multiple heights if you want adjustable cooking levels — simply build two or three sets of ledges at different courses.
Method 2 — Steel Angle Iron Ledges
Embed 50 × 50 mm steel angle iron (or flat bar) into the mortar joints on each side wall at your chosen grate height. This gives a very clean, strong support.
- Cut the angle iron to span the full internal width.
- Bed it into the mortar joint as you lay that course, ensuring it's level.
- Allow at least 50 mm of embedment into the brickwork on each side.
- Use stainless steel angle iron to resist rust from heat and weather. Note that galvanised steel can release zinc fumes when exposed to high heat near food — stainless steel is the safer choice for firebox applications.
- You can install multiple sets at different heights for cooking flexibility.
A standard cooking grate sits well at around 300–350 mm above the base of the firebox. A second grate support 100–150 mm higher gives you a warming rack option.
Finishing Touches
- Cap the top of the side and back walls with a course of bricks laid flat, or use a purpose-made coping brick to shed rain.
- Pointing: Once the mortar has gone firm (not fully hard), rake joints to around 10 mm depth and finish with a pointing tool for a neat, weather-resistant finish.
- First firing: Cure your BBQ slowly. Light a small fire and let it burn for 30–45 minutes, then allow it to cool completely. Repeat two or three times before cooking on it. This prevents thermal shock cracking the mortar.
- Consider a stainless steel ash drawer or simply leave a gap at the base of the front opening for ash removal.
Safety Notes
- Never use concrete blocks or pavers inside the firebox — they can spall (explode) when exposed to intense heat. Always use firebricks.
- Keep the BBQ well clear of any combustible structures. WorkSafe NZ has general guidance on outdoor fire safety.
- Check your local council's bylaws regarding open fires — some areas have restrictions, particularly during dry summer periods.
- Ensure children and pets are kept well away during construction and use.
When to Call a Professional
For a straightforward garden brick barbecue, a competent DIYer can handle the full build. However, consider hiring a qualified bricklayer if:
- Your site has uneven or unstable ground requiring engineered footings.
- You want a more complex design with arches, a chimney flue, or integrated benchtops.
- You're not confident with brickwork and mortar mixing.
- The project is larger than a simple freestanding BBQ (larger structures may require building consent — always check with your council, and visit MBIE Building Performance for guidance on consent requirements).
A skilled local bricklayer will get the job done efficiently and to a high standard. You can find qualified tradespeople in your area on tradedirectory.co.nz.
Licensed Building Practitioner (LBP)
