How do I choose an insulation installer?

Two houses can have identical batts in the ceiling and perform very differently. Insulation works by trapping still air, so every gap, every section compressed under a sagging blanket and every patch left short at the edges leaks heat out of the result. Because the work hides in the ceiling and under the floor, you will probably never see the difference. The installer's habits are the product.

That is also why the cheapest quote so often costs the most per degree of warmth gained.

NZS 4246 is the standard for installing insulation in existing houses, and it is the question that sorts installers quickly: ask how they work to it and listen for specifics. Clearances around downlights, flues and chimneys are about fire risk, and care around old wiring matters in older ceilings.

Foil insulation is the hard line. Installing or repairing it in residential buildings has been banned since 2016 after fatal electrocutions, so any suggestion of laying new foil is a reason to stop. WorkSafe and EECA both publish guidance if you strike an edge case.

Warmer Kiwi Homes, the EECA programme, covers a large share of ceiling and underfloor insulation costs for eligible homeowners, and the work has to be done by an installer approved under the programme. Eligibility and the current installer list live on the EECA website.

If you are insulating a rental, the healthy homes standards set minimum requirements for ceiling and underfloor insulation, and Tenancy Services is the authority on what compliant looks like.

A good quote names the product, its R-value, the area covered and how edges, hatches and awkward corners are handled. Vague line items like ceiling insulation supplied and fitted give you nothing to hold anyone to.

Ask for photos of the finished work, since you are unlikely to crawl under the house yourself. Reputable installers take them as a matter of course, and a before-and-after set is reasonable to request with the final invoice.

Finally, ask what happens to any old insulation that comes out. Removal and disposal is either in the quote or it is not, and finding out at invoice time is the wrong moment.