Roof insulation is one of the easiest, simplest ways to improve the energy efficiency of your home, increase its value and reduce your heating bills. In addition, it helps to maintain a pleasant indoor temperature year-round and limits the formation of moisture inside the house, keeping your home healthy and comfortable.
The most common roofing insulation type is fiberglass. It is a low-density, lightweight material that provides high R values and is very easy to install.
Other popular types of roof insulation include mineral wool, which is made from either rock or slag wool, and PIR (polyisocyanurate) insulation board, which is very durable and dimensionally stable.

Generally speaking, roof insulation should be installed below the roof membrane, where it will provide protection against condensation and help to prevent water damage to the underside of the roofing material. In warm, humid climate zones (climate zone 1 or 2), a layer of reflective insulation, such as sarking batts or foil batts, should be used to increase resistance to radiant heat.
Insulation types for a roof may vary by climate region and the size of the roof. It is important to consult with a roofing contractor and your local building code to determine the proper thickness of insulation for your roof.
Suitable bulk insulation includes batts, loose-fill and rigid foam boards such as PIR or XPS. It should be installed between rafters, with the rafters compressed slightly to remove air gaps that can affect the insulation's R value.