Perth concrete patios & alfresco price bands
| Band | $/m² (supplied and installed) | What puts a job in this band |
|---|---|---|
| Low | $110–$130 / m² | Standard rectangular alfresco extension, exposed aggregate in WA quartz or river pebble, level access, existing house slab to tie into. Common for backyard patios in new-estate blocks. |
| Mid | $130–$160 / m² | Liquid limestone or honed finish, curved edge or feature saw-cuts, cut-outs for drainage and posts, custom colour. Most common band for full alfresco extensions in established Perth suburbs. |
| High | $160–$180 / m² | Premium aggregate, complex shape wrapping around pool or garden features, integrated step-down, feature lighting inserts. Common in Applecross, City Beach, Cottesloe premium builds. |
What drives the cost in Perth
Finish choice
Plain broom finish is cheapest but rarely used for alfrescos — homeowners want visual quality. Exposed aggregate and liquid limestone are the two mid-tier defaults ($20–$40 per m² over plain). Honed or polished alfrescos run at the top of the price band and demand a higher-quality pour.
Tie-in to existing structure
Alfrescos usually extend from the house slab. A cold joint against the existing slab needs proper preparation — cleaning, priming, and a dowel bar connection where the pours meet. Not doing this properly leads to a visible crack along the join within 12 months.
Fall and drainage
Alfresco slabs need a 1:100 minimum fall away from the house. Adding a strip drain at the outer edge to prevent water pooling adds $250–$400. Absolutely essential on covered alfrescos where rain runs off the roof onto the slab edge.
Post cut-outs and cast-ins
Alfrescos supporting a patio roof need cast-in post plates or engineered cut-outs. Getting these positioned accurately before the pour is worth the extra half-day of setup — retrofitting mounts adds $150–$300 per post and rarely looks as clean.
Access and formwork
Backyard alfrescos usually mean pump access, which adds $700–$1,200 for the pump-truck day. Complex curved formwork adds a day of setup labour. Rectangular slabs against a straight rear wall are the cheapest layouts to pour.
Process
- 1
Excavation and base
Excavate to firm subgrade, allowing for 100mm base plus 100mm slab plus finish thickness (10–20mm for liquid limestone topping). Compact road base in two lifts.
- 2
Formwork, fall and drainage
Set formwork with 1:100 minimum fall away from the house. Install underground drainage rough-ins and strip drain if specified. Position post plates or cast-in fixings for any roof structure.
- 3
Reinforcement
Vapour barrier over the base. SL72 mesh on 40mm bar chairs for standard alfrescos; SL82 if the slab supports a patio roof structure. Overlap sheets 225mm minimum. Dowel bars into any existing house slab at the cold joint.
- 4
Pour and screed
Pour a 25 MPa mix for standard finishes; 32 MPa for honed or polished. Screed to the fall line, bull-float, and prepare for the specified finish.
- 5
Finishing
For exposed aggregate: retarder spray immediately after floating, wash off at the right window. For liquid limestone: cure the base 21 days then apply topping. For honed: cure and diamond-grind after 14 days.
- 6
Seal or densify
Sealer choice matches the finish — solvent-based UV-stable sealer for exposed aggregate, penetrating sealer for liquid limestone, lithium densifier for honed. Apply after 21 days minimum. Always solvent-based in Perth.
Perth-specific considerations
- Alfresco slabs in Perth are almost always under a roof or pergola, which changes the sun exposure calculation — mid-tone colours look great year-round rather than showing dirt like they might on an exposed driveway.
- The reactive Guildford clay through the eastern corridor causes slab movement that reads badly on a smooth alfresco finish. On clay, insist on more control joints and a heavier mesh (SL82 minimum).
- For alfrescos near pools, chlorinated water splash attacks unsealed concrete edges. Reseal alfresco edges every 2 years within splash range, whatever the finish.
- Perth's dominant afternoon sea breeze off the coast drives fine sand onto covered alfrescos in Alkimos, Cottesloe, City Beach. A smoother finish (liquid limestone or honed) sweeps clean faster than a rough exposed aggregate.
- Cast-in post plates for patio roofs must match the roof structure's engineering. Talk to the patio roof supplier before the pour so the plates go in the right positions with the right load rating.
Compare with the alternatives
Liquid limestone for alfrescos
Liquid limestone is the single most popular alfresco finish in coastal Perth — cool, pale, forgiving. Read the dedicated liquid limestone page for full detail on colour options and maintenance.
Read more →Exposed aggregate alfrescos
Exposed aggregate is more durable and hides marks better than liquid limestone, but it's rougher underfoot and less coastal-looking. Great for family alfrescos that see daily use.
Read more →Ready for a concrete patios & alfresco estimate?
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Frequently asked questions
How much does a concrete alfresco slab cost in Perth?
A 30m² alfresco slab in exposed aggregate runs $3,300–$4,800. The same slab in liquid limestone runs $3,300–$4,500. Add $400–$600 for post cut-outs and drainage if you're extending under a new patio roof.
What's the best finish for a Perth alfresco?
Depends on how you use it. For barefoot family use around a pool, liquid limestone or a mid-tone honed finish stays coolest. For a heavy-use alfresco with outdoor kitchen and furniture, exposed aggregate hides marks best. For a designer look under a modern architectural roof, honed concrete is the most premium.
Do I need council approval for an alfresco slab?
The slab itself doesn't need approval. If the alfresco has a fixed patio roof structure, that structure will need a building permit through your LGA — the slab pour and roof structure permit are often bundled if a single builder is coordinating the job.
How long before I can put furniture on a new alfresco slab?
Light furniture after 7 days if the slab has been damp-cured. Heavy outdoor kitchens and permanent fixtures after 28 days when the slab reaches design strength. Wait the full 21–28 days before sealing so trapped moisture escapes.
Can an alfresco slab tie into my existing house slab?
Yes, with proper preparation. The existing slab edge is cleaned, roughened, and doweled with reinforcement bars drilled and epoxy-set at 400mm centres. The new pour bonds into the dowels. Without dowels, expect a visible crack along the join within a year.
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