R Values Explained

Insulation’s effectiveness in restricting the flow of heat is measured by its R Value. The higher the material’s R value, the greater the material's heat insulation effectiveness and slower the heat flow through it.

In New Zealand the Building Code specifies minimum R values for 3 different climate zones, which broadly are:

1. The Thames-Coromandel and Franklin districts and all districts north of these.
2. All the North Island excluding zone 1.
3. The Taupo and Ruapehu districts and part of the Rangitikei district plus all of the South Island.

The requirements in each zone are set out in the New Zealand Building Code.

BRANZ (Building Research Association of New Zealand) has several checklists, worksheets and guidelines that can help you determine whatR level insulation you need.

Design Navigator is another user friendly tool for establishing required R values.