Insulating your home: a guide to a job you'll feel every season

What an insulation job involves

Insulation installers fit thermal and acoustic material into the parts of your home that leak heat: ceilings and roof spaces, walls, and under floors. Ceiling batts in the roof space are the most common and highest-value job; wall insulation is straightforward in a new build or during a renovation but harder to retrofit into finished walls; underfloor insulation suits raised timber floors.

The material is rated by R-value — its resistance to heat flow — and higher R-values insulate better. Bulk insulation like glasswool or polyester batts is the standard; reflective foil and rigid boards suit particular situations. A good installer matches the material and R-value to the part of the house and your climate zone rather than fitting one product everywhere.

How insulation is priced

Insulation is quoted per square metre, so the area to cover and the R-value you choose set the band — a ceiling top-up on an average home lands in the low thousands, while insulating a whole home across ceiling, walls and floor climbs from there. Higher R-value products cost more per metre, and retrofitting into finished walls is far more labour-intensive than an open ceiling space.

Access and existing conditions move the number. A clear, accessible roof space is quick; a low-pitch roof, an old home with existing insulation to remove, or wiring and downlights to work around all add time. Treat the figures here as indicative — the live prices give a starting range, but coverage area and R-value are what set your real quote.

Choosing an insulation installer

Insulation installation is generally not a licensed trade in its own right, though it intersects with regulated safety rules — particularly the clearances required around downlights, exhaust fans and flues, where insulation packed too close is a genuine fire risk. Look for installers who work to the Australian Standard, carry insurance, and talk about those clearances without prompting.

The detail that decides value is what you can't see once the job's done. Ask for the R-value in writing, and confirm they'll install to full coverage with no gaps — because batts stuffed loosely with cold bridges between them underperform the rating on the label. A reputable installer is happy to show you photos of the finished roof space.

Mistakes to avoid

The classic insulation mistake is buying a number on paper and getting less in the ceiling — the right R-value on the invoice, but gappy coverage and unsafe clearances in the roof space where nobody's looking.

• Not getting the R-value and coverage area stated in writing
• Accepting gappy, poorly fitted batts that underperform the rating you paid for
• Ignoring clearances around downlights, fans and flues — that's a fire risk, not a detail
• Insulating the ceiling but leaving obvious gaps like an uninsulated access hatch
• Choosing the cheapest product without matching the R-value to your climate zone