Free insulation calculator. Wall, ceiling, and underfloor batt counts for NZ residential builds.
This calculator turns ceiling, wall and underfloor areas into the quantity of insulation to order, at the R-value you are specifying. You supply the R-value. CostMate does not tell you what it should be, and the reason why is worth reading.
It used to. Until 20 August 2026 this page held a region to climate zone lookup and printed a minimum R-value for each element. That was removed, and it is not coming back.
The 6th Edition of H1 (Energy Efficiency), effective 27 November 2025, deleted the schedule method — the table you could look a number up in. What remains is a calculation method and a modelling method, and both of them trade insulation off between roof, wall, floor and glazing against a whole-building heat-loss target.
So there is no longer a per-element R-value to look up. A tool that printed one would be inventing an answer to a question the current document no longer asks that way.
There was a second problem. The figures the page had been printing came from the previous edition's schedule, and the region selector driving them held zone numbers that disagreed with CostMate's own estimating engine. Rather than ship a third, differently wrong zone table, the tool now does the part that is still straightforwardly true: the take-off.
Pick the elements you are insulating — ceiling, walls, underfloor, or any combination — enter the area of each and the R-value you are specifying for it, and the page returns the quantity to order with 10% added for wastage.
The R-value travels through to the output, so the order note says what you specified. That is what a merchant needs, and it is worth having written down when someone asks later what went in.
The R-value for a given building is a design decision. Take it from your plans or your designer, and confirm product coverage with your supplier, before you order.