A standard ceiling batt retrofit costs $20-$40 per m2 supplied and installed for most homes. Jobs that include removing old insulation run $30-$50 per m2. It is one of the highest-return home upgrades there is - here is what it should cost.
| Item | Range | Notes |
|---|---|---|
| Ceiling batts, supply only - R3.5 glasswool | $8-$15/m2 | The DIY starting point. |
| Supply by R-value | R2.5 $7-$11/m2; R4.0 $10-$14/m2 | Each R-step adds roughly $3-$6/m2 of material. |
| Professional installation (labour) | +$8-$20/m2 | On top of batt supply. |
| Fully installed retrofit, R4.0 | $20-$33/m2 | Published guide table figure for a standard install. |
| Headline for most homes (R4.0-R5.0, no removal) | $20-$40/m2 | Guide-publisher bands reconciled against installer pricing; premium metro installers publish $30-$70/m2. |
| Remove old + vacuum + install new R4 batts | $30-$35/m2 + GST | Published installer package (Oz-Roof, Adelaide). Overall, removal/replacement jobs land at $30-$50/m2. |
| Old insulation removal only | From $15/m2 - indicative | Including disposal; single installer source, so treat as indicative. |
Published worked examples put a 150 m2 ceiling at $2,700-$5,250 for an R3.5-class job, and a 120 m2 lower-spec home at $1,600-$3,000. Batts come in packs - a standard 580 x 1160 mm batt covers about 0.67 m2, so around 150 batts per 100 m2 - and a standard 10% waste allowance applies, which is why small ceilings waste proportionally more.
The biggest single swing on retrofit jobs: from about $15/m2 before new batts go in, with full remove-vacuum-replace packages at $30-$35/m2 + GST even at R4. If your old insulation is sound, a top-up is far cheaper.
Tight roof spaces and complex or multi-storey roofs cost more. One installer's guide prices straightforward professional work at $35-$70/m2 against $70-$110+/m2 for tight-access roof insulation work.
Stepping R2.5 to R4.0 to R5.0+ lifts material cost roughly $3-$6/m2 per step while labour barely changes - upgrading R-value mid-job is cheap relative to the benefit.
Insulation must keep required clearances around downlights or be fitted around IC-rated fittings. Fiddly ceilings with many fittings price higher - and this is a safety issue, not just a cost one (below).
Batts come in fixed pack sizes with a 10% waste allowance, so very small ceilings carry a higher effective per-m2 cost.
Schemes such as Victoria's VEU and NSW's ESS can discount eligible installs. Amounts vary and change over time, so we note their existence rather than publishing a dollar figure - ask your installer what applies at quote stage.
$3,600-$5,700
No existing insulation, standard access, professionally installed: 150 m2 x $24-$38. It sits just above the published $2,700-$5,250 for an R3.5-class job of the same size - exactly as an R5.0 upgrade should.
$4,200-$5,760
Installed band $20-$33/m2 plus the $15/m2 removal allowance, landing inside the published $30-$50/m2 removal-job headline.
$2,400-$3,960
The cheapest professional path when the existing insulation is sound - less labour, no removal, no full coverage pass.
$1,000-$1,400 + your weekend
Supply at $10-$14/m2, and about 165 batts once the 10% waste allowance is counted. Read the safety notes below first.
Compliance and safety: the National Construction Code sets minimum R-values by climate zone - there are 8 zones, with ceiling minimums from about R2.7 in Darwin's hot zone 1 up to higher requirements in cold and alpine zones; check the NCC for your zone rather than relying on a generic table. Choose products that comply with AS/NZS 4859.1. Critically, insulation must not cover non-IC-rated downlights or electrical fittings - it is a fire risk - and in some states insulation work around electrical is restricted, which is a strong reason to use a professional on complex ceilings. DIY batt installation is legal in most states, but keep downlight clearances and wear PPE (P2 mask and gloves).
Prices cross-checked against IndoorCalc, Guiding Expert and Insulation Easy guides and installer rate cards (Oz-Roof, 1 Stop Insulation, Mornington Peninsula Roofing), October 2026. Figures are guides, not quotes.
A standard ceiling batt retrofit costs $20-$40 per m2 supplied and installed for most homes. Jobs that include removing old insulation run $30-$50 per m2. It is one of the highest-return home upgrades there is - here is what it should cost.
The biggest drivers are removal of old insulation, roof access and pitch, r-value steps and downlights and fittings. Each one is worked through with prices in the guide above, and the calculator prices them for your job.
Use the free calculator linked from this guide - it prices your job with the same installed ranges used here, in about 30 seconds. It is a guide range, not a quote: your contractor confirms a fixed price after seeing the job.
No - they are researched guide ranges, cross-checked across at least two published sources, not quotes. Prices move with your area, the condition of the site and the scope you choose. Get itemised quotes in writing, and check the tradesperson's licence with your state building authority before you book.
R-value, removal, access - plus a DIY mode that counts your batts for you.