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Roofing Insulation: The Most Common Types

Published on September 8th, 2020

Common Types Of Roofing Insulation

You roof insulation process is a really important aspect of your home’s completion. It must be done properly and installers must pay attention to the applicable energy codes, the thermal needs of the building and “deliver a roof assembly acceptable to the facility’s insurance carrier.”

That’s why your roofing contractor needs to properly install your insulations and ensure that they use the correct type of insulation to complete your roof. There are seven different types of materials used for insulation: “wood fiber, perlite, polyisocyanurate, expanded or extruded polystyrene, cellular glass, and gypsum board.” We’ll give you some general information about each of them now.

Wood Fiber:

  • Organic insulation board.
  • Made of cane, wood or vegetable fibers (mixed with fillers and binders).
  • May be asphalt coated or asphalt impregnated to help it resist moisture.


  • Inorganic insulation board.
  • Made of expanded silicaceous volcanic glass.
  • Asphalt coating or proprietary coating on the top surface (limits adhesive “absorption into the insulation during the roof-membrane application.”)


  • Consists of closed-cell foam plastic insulating core, in-between “organic or inorganic felt facers, glass-fiber mat facers, or glass-fiber-reinforced aluminum foil facers.”
  • High thermal resistance: a blowing agent (not made with chlorine) expands the foam material.

Polystyrene Insulation (expanded and extruded):


  • Saturated with foaming agent that expands when exposed to heat.
  • Available in 0.70 – 3 pounds per cubic foot (pcf).


  • Made of blended polystyrene polymer
  • Passed through an extrusion process.
  • Expands and causes its closed cell structures when it is exposed to atmospheric conditions.
  • Available in 1.3 – 2.2 pounds per cubic foot (pcf).

Cellular Glass:

  • Made up of a foaming agent mixed with crushed glass.
  • The foaming agent and crushed glass are combined, put in a mold and heated, resulting in the decomposition of the foaming agent and the melting of the glass (this causes the material to expand and to create uniform, connected closed cells that result in the insulating material required).

Gypsum Board:

  • It is a treated gypsum core panel.
  • It is non-structural, non-combustible and water-resistant.
  • Can be used as a thermal barrier over a steel deck.
  • Can be used as a vapor-retarder substrate.
  • Can be used as a cover board over foam-plastic insulations.

These different insulation materials may all sound pretty complicated and that’s why you need the experts to help you through your roof insulation process. We know all about this roofing  business, so if you need the help of roof contractors to get an inspection and a free estimate for your roof installation, repair, or replacement, get in touch with us today. Right where you are in Nashville, you can find the best service for all your roofing needs. We’re Nashville Metal Roofing and we care about you and your home’s renovation.

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Showalter Roofing Services, Inc.

2183 Hillsboro Road, Suite 206, Franklin, TN 37069

(615) 266-2625

Fax: 865-381-1533