What does R-Value mean? How much do I need?

What R-value insulation should be installed in a New Zealand home?

The R-Value – or R-Rating of thermal insulation measures how resistant the insulation is to heat transfer. A higher R-value means a higher resistance to heat transfer. New buildings are generally specified at the design stage as requiring a certain R-value. Before recommending the insulation R-value, consideration will be given to things such as the climate zone, (temperature variations, humidity etc) the design of the house, including which building materials are used, and the effect of any shading and direct sunlight on the building.

How insulation works

If your existing home currently has no thermal insulation installed in the ceiling, then installing insulation of any R-Value will in most cases significantly reduce the amount of heat transfer into your house in summer and the amount of heating which escapes your home in the winter. Thermal insulation simply acts as a barrier for heat transfer.

Use the recommended R-Value for your project

How much does it cost to insulate a roof? If I double the R-value, will I double the savings on my energy costs? Probably not! If your home has been specified as needing an R3.0 insulation in the ceiling, upgrading to an R6.0 will perhaps double the insulation cost, but it’s unlikely that this cost would be saved back by further reductions to your energy bills. As a rule of thumb, we recommend you work off what has been specified, or, on the assumption that electricity prices will continue to rise – you may consider upgrading to a slightly higher R-value.

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