You need to add insulation to get the proper R-value for the climate you live in. R-Value is a measure of the ability of the insulation to retard heat flow . A higher number indicates better insulation protection.

The region where I live requires a 49 R-Value in the attic. Check the manufacturer's website for the amount of insulation you will need for area. There are online calculators which can help to determine the amount of material you will need.

When adding above the floor joists you will need to use " unfaced" battens. This material does not have the paper vapor barrier.