Buildmagazine.org.nz has reported (01/02/2015) on retrofitting insulation to an existing home to maximise thermal performance.
Home insulation will benefit the home by keeping it cooler in summer and warmer in winter and can also reduce the risk of condensation which means a healthier living environment for the occupants due to less mildew and mould.
The R-value of insulation refers to the amount of resistance to heat flow through a given thickness of insulation material. Better insulation will have a higher R-value as long as it is installed properly with no compression points or gaps and fully dry.
Houses built before the 1970s are unlikely to have insulation in the walls but it may have been retrofitted in the ceiling and floor. Houses built between 1979 and 2007 are likely to have lower R-value insulation installed than current standards require.
Minimum R-values for wall, ceiling and floor insulation are found in the schedule method of NZS 4218:2009.
Consider the R-value you are aiming to achieve, the thickness of insulation required and the labour cost to install it. When comparing prices, you may find that the most expensive product may be the most economic overall.
The most cost-effective time to upgrade your home insulation is during renovations.