How much insulation do I need?

Work out the area of the ceiling, wall, or floor to insulate, then divide by the coverage of one pack. The calculator does this and rounds up to whole packs. Coverage is printed on the pack and varies with the segment width and R-value.

What R-value do I need in New Zealand?

The Building Code sets minimum R-values that vary by climate zone and by whether it is a ceiling, wall, or floor. Ceilings need the highest. Check the current requirements for your area and choose a product that meets or beats them.

Should I allow for framing?

Insulation fits between the framing, so the actual segment area is a little less than the gross area. Buying to the gross area gives a small safety margin and covers offcuts, which is sensible.

Insulation Calculator

Work out how many packs of insulation to buy. Enter the area to insulate and the coverage printed on the pack, and the calculator shows the packs needed. Choose a product that meets the R-value required for your climate zone and the part of the house you are insulating.

Area to insulate (m²)

Coverage per pack (m²)

0 packs

to buy

Area covered0 m²

Check the R-value meets the Building Code for your zone and the ceiling, wall, or floor.

How it works

Divide the area you are insulating by the coverage of one pack and round up to whole packs. Coverage depends on the segment width and the R-value of the product, so always use the figure on the pack you are buying.

Worked example

For an 80 square metre ceiling with packs that cover 8.16 square metres each, you need 80 divided by 8.16, which rounds up to 10 packs.

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