Insulation Calculator

New Zealand insulation requirements depend on whether the home is a new build or an existing rental. For new builds, NZ Building Code clause H1 (Energy Efficiency) now requires a much higher ceiling than before: under the current schedule method the roof/ceiling R-value is R6.6 across all six climate zones (H1/AS1 5th edition from 2022; 6th edition from 27 November 2025). Walls and floors also have minimum R-values that rose under the 2022 H1 update — check the current H1/AS1 schedule for your climate zone. For existing rental homes, the Healthy Homes Standards require a minimum ceiling R-value of R2.9 in Zones 1-2 and R3.3 in Zone 3, plus underfloor insulation of at least R1.3. NZ climate zones run from Zone 1 (warmest — the Far North) to Zone 6 (coldest — Central Otago). Source: building.govt.nz (H1/AS1 Energy Efficiency); Tenancy Services tenancy.govt.nz (Healthy Homes).

Insulation costs in New Zealand vary significantly depending on the type and the home's construction. Ceiling insulation for an average three-bedroom NZ home typically costs $1,500-4,000 installed, depending on R-value and accessibility. Underfloor insulation generally costs $2,000-5,000 for the same home, depending on subfloor access and ground clearance. Wall insulation in an existing home is the most expensive option, costing $5,000-15,000 or more, because it requires either removing interior linings or drilling and blowing in loose-fill insulation. New build wall insulation is much cheaper, as batts are installed before wall linings go on. Labour and accessibility are the main cost drivers. Always use a registered insulation installer. Source: EECA energywise.govt.nz; Tenancy Services tenancy.govt.nz.

Yes, New Zealand has government subsidies for home insulation through the Warmer Kiwi Homes programme, administered by EECA (Energy Efficiency and Conservation Authority). Eligible homeowners can receive free or subsidised ceiling and underfloor insulation. To qualify, you generally need to own and live in a home built before 2000, and receive a qualifying government benefit or Community Services Card, or live in a lower-income area (as defined by the programme). The subsidy covers up to 80% of the cost for most eligible homeowners, with community service card holders and those in certain areas receiving 90%. Heating subsidies are also available for eligible homes. Contact EECA or a registered installer to check eligibility. Source: EECA energywise.govt.nz; Warmer Kiwi Homes warmerkiwihomes.govt.nz.

To calculate insulation quantities, measure the area to be insulated in square metres. For ceiling insulation, measure the ceiling area of each room and sum them, excluding areas already insulated. For underfloor insulation, measure the subfloor area — typically the same as the ground floor area minus internal walls. Batts come in standard widths of 430mm and 580mm to fit between joists or rafters spaced at 400mm and 600mm centres respectively; choose the correct width for your joist spacing. Divide the total area by the batt coverage per pack to determine how many packs you need. Add 5-10% for waste and offcuts around obstacles. For loose-fill blown insulation, the installer will calculate the required depth and coverage. Source: EECA energywise.govt.nz; Tenancy Services tenancy.govt.nz.