Cavity Wall Insulation Cost Calculator & Price Guide
Cavity wall insulation can make brick homes more comfortable and energy efficient, with wall insulation installation costs varying by material, access and cavity condition. In Australia, typical supply-and-install pricing ranges from about $28/m² for polystyrene bead pump in wall insulation to $48/m² for foam injection, with blown mineral wool sitting at $35/m², all in AUD before any access, cavity clearing or make-good extras.
Estimate cavity wall insulation cost
Supply-and-install midpoints for blowing or pumping insulation into an existing wall cavity in Australia. Rates cover the fill and patching the drill holes in the mortar. A second storey, a tight side, and making good a rendered wall are extra. Ceiling and underfloor insulation are a different job.
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Cavity Wall Insulation Price Breakdown
Typical job based on 100 m². Prices are supply-and-install midpoints — actual quotes will vary.
| Type | Cost per m² | Typical 100 m² job |
|---|---|---|
| Blown mineral wool | $35 | $3,500 |
| Polystyrene beads | $28 | $2,800 |
| Foam injection | $48 | $4,800 |
What Affects Cavity Wall Insulation Cost?
- Insulation material: The biggest driver of wall insulation cost is the fill type you choose. Polystyrene beads are priced at $28/m², blown mineral wool at $35/m², and foam injection at $48/m² for supply and install.
- Cavity condition: A clear cavity ready to fill is included in the base rate, but costs increase when the cavity needs preparation. Empty means a clear cavity ready to fill, while needs clearing means debris or old fill to work around before the new insulation goes in, adding $12/m².
- Access and storeys: Access affects labour time and setup, so the calculator applies multipliers to the main insulation and cavity-clearing costs. Single storey, clear access is ×1, double storey is ×1.2, and a tight side access or heritage facade is ×1.4.
- Rendered wall make-good: If holes need to be patched and finished in rendered surfaces after installation, you can add a flat make-good allowance. This optional extra is $650 when required.
Cavity Wall Insulation Cost - Frequently Asked Questions
For standard supply and install, cavity wall insulation costs $28/m² for polystyrene beads, $35/m² for blown mineral wool, and $48/m² for foam injection. If the cavity needs clearing first, add $12/m². The displayed estimate range is typically shown at ±20% around the midpoint, and a minimum job charge of $1500 AUD applies when the calculated total falls below that.
Using the default 100 m² example with single storey, clear access and a clear cavity, wall cavity insulation works out to $2,800 for polystyrene beads, $3,500 for blown mineral wool, or $4,800 for foam injection. If the cavity needs clearing, add $1,200 to any of those totals. If rendered wall make-good is needed, add another $650.
Yes. Blow in wall insulation using blown mineral wool is priced at $35/m², while foam injection is $48/m², so mineral wool is the lower-cost option based on the calculator rates. On a 100 m² job with clear access, that is $3,500 versus $4,800 before any extras.
Retrofit wall insulation uses the same base rates, then applies the access multiplier to the insulation and any cavity-clearing costs. For a 100 m² double-storey job, the insulation component becomes $3,360 for polystyrene beads, $4,200 for blown mineral wool, or $5,760 for foam injection before optional make-good. If the cavity needs clearing, the $12/m² adder also gets multiplied by 1.2, adding $1,440.
For brick cavity wall insulation, the main price drivers are the insulation type, whether the cavity is empty or needs clearing, and how easy the walls are to access. Tight side access or a heritage facade uses a ×1.4 multiplier, while double storey uses ×1.2. If a rendered wall also needs to be made good after wall insulation installation, add $650.
Pump in wall insulation with polystyrene beads starts at $28/m² under single storey, clear access conditions. With tight side access or a heritage facade, the calculator applies a ×1.4 multiplier, taking the insulation component to $39.20/m² before any cavity-clearing or make-good extras. If the cavity needs clearing, that $12/m² adder is also multiplied by 1.4.
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