In San Antonio the recommended amount of insulation is 13″ or R38. R means resistance to heat flow. The higher the R-value, the greater the insulating power.
If your home has less than 13″, in the warm months, heat can penetrate from your attic down into the home. In the cooler seasons when we are heating the homes, heat can easily escape from within the home without enough insulation to hold it in.
There are other factors to consider. The amount of insulation you need depends mainly on the climate, the type
and size of your home, and your fuel use patterns and family size. To get the marked R-value, it is essential that this insulation be installed properly.
Duct work should also periodically be evaluated for rips, tears, and broken or leaking seals to the HVAC equipment and supply registers in each room. Don’t pay to air condition your attic!