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What Should I Know About Styrofoam™ Insulation?

By M.R. Anglin
Updated May 17, 2024
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Styrofoam™ is a brand name of the Dow Company and is used to make insulation, floral, and craft materials. Even though the word is a registered trademark, it is often used to refer to any expanded polystyrene foam used to make cups, packing materials, and other products. Styrofoam™ is commonly used as insulation in construction because of its unique properties. When used as insulation, it is cut into sheets or slabs and is commonly referred to as “blue board” in construction.

Styrofoam™ is light and waterproof and that makes it ideal as building insulation. Its closed cell structure means that Styrofoam™ insulation has a high R-value. R-value refers to the ability of a material to conduct heat. The higher the value a substance has, the more resistant it is to conducting heat.

Proper insulation does not allow heat to transfer into or out of a building and that reduces drafts and lowers heating and cooling costs. This means that a building will stay warm in the winter and cool in the summer.

Styrofoam™ insulation’s structure means that there is virtually no empty space between its cells. This means that the product is strong and waterproof. Since it is so resistant to water, mildew and mold are unable to grow on its surface.

Styrofoam™ insulation is cut into sheets which are then installed in the outside foundation walls or attached to the frame of the building. The foam can then be covered with different materials in order to create a certain look, such as stucco, stone, or marble. Light can degrade Styrofoam™ insulation. To counteract this problem, the foam should be installed with a light blocking material in order to protect it.

Styrofoam™ insulation is also used as floor insulation and roof insulation. On roofs, Styrofoam™ can be cut and used to provide appropriate drainage. It can also be installed in a log cabin. After it is laid on ceiling material, plywood or other materials can be placed over it. Shingles are then able to be installed over that.

One important factor that should be considered about Styrofoam™ is its effect on the environment. Styrofoam™ does not break down easily and can be ingested by animals and block their digestive tracts. However, Styrofoam™ is durable which means that it can be reused. Reusing Styrofoam™ insulation can cut the cost of future renovations and repairs.

About Mechanics is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Discussion Comments
By anon299331 — On Oct 24, 2012

We have insulated our garage doors and would like to know if there is a tape that will stick and hold it? We are unable to find one as of yet. Please help?

By anon244942 — On Feb 03, 2012

What bug eats styrofoam?

By anon181720 — On May 30, 2011

I was checking my through the wall A/C and the vent that blows the air out is lined with polystyrene. Upon closer inspection, I noticed that it was covered in black mold, or what appears to be black mold.

In the article above, it states that mold cannot grow on polystyrene: "Since it is so resistant to water, mildew and mold are unable to grow on its surface. " Any ideas?

By anon138713 — On Jan 02, 2011

We need to insulate our home. We have 12ft ceilings.

We have no Attic and a tile roof. What product could we use under the tile to bring it up to R 30?

Thank you in advance.

By jackan — On Dec 17, 2010

Does Styrofoam release formaldehyde or any other potentially harmful vapors?

am new here. I can read all of the questions, but not any of the responses. How do I do that?)


By anon126084 — On Nov 11, 2010

is Styrofoam good for insulation in a lunch box that has to stay cool?

By anon113820 — On Sep 26, 2010

Is it advisable to "wall up" storefront plate glass with styrofoam sheet insulation to block heat? I was thinking of using foil-backed sheets against the glass and cover the sheets inside with paneling. Please offer any thoughts.

By anon54860 — On Dec 02, 2009

I live in a house in Germany with polystyrene insulation, surrounded by drywall. I have tried hanging wooden curtain rods and found that the weight of my curtains and the rod pull the screws, and the plastic piece that i put the screw into, out of the walls.

I was told to use an anchor of some sort that would expand behind the drywall, but due to the insulation that isn't possible from what I know. Is there an alternate solution?

By anon51303 — On Nov 04, 2009

is it possible for polystyrene insulation to break to a point where it is in powder form?

By anon44019 — On Sep 03, 2009

can i use styrofoam insulation sheets on interior basement walls.

By anon35412 — On Jul 05, 2009

I have had styrofoam insulation around my foundation for years. I started to do a reno job and had to remove some of the styro and found it full of 3/8 inch worm type holes. I thought it was bug proof but some kind of bug sure likes to eat its way through 2 1/2 inch board back and forth as if it liked to eat it. any ideas

By hmcclung — On Jun 27, 2009

I want to know if styrofoam can be cut to size

and used over a window to keep heat out of the room?

By anon30822 — On Apr 25, 2009

Does it make sense on a 25 year-old mobile home to have sears residing with polysterene foam for $6,000? and would we qualify for a gov. rebate?

Thanks in advance!

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