Is Exposed Insulation In A Basement Dangerous?

Many unfinished basements have a less than inviting look to them, and it's not uncommon to find issues that you would never expect elsewhere in a home. One of the most commonly found basement issues is exposed insulation, just left for everyone to see. But is that dangerous? We've researched whether exposed insulation is hazardous to get the answer for you.

Insulation should never be left exposed in a basement. Whether your home has spray foam, foam board, or fiberglass roll (or batten) insulation, each type should always be covered because each poses hazards such as:

  • Fire risk
  • Irritated skin issues (due to chemical irritants in the materials)
  • Respiratory issues (due to chemical irritants in the materials)

Please keep reading to find out more about the specific concerns for each type of insulation and possible solutions. We'll also give you some recommendations on how to cover insulation and how to fend against moisture build-up in your unfinished basement.

A ceiling insulation of a house with skylight on the side, Is Exposed Insulation In A Basement Dangerous?

Insulation Is A Recognized Fire Hazard

The number one concern with exposed insulation is that it is a fire hazard. There is no insulation available that does not have some sort of limitation on its use, simply because of the risk that it may burn. All insulation contains chemicals that would be incredibly toxic in a fire, posing even more risk to the homeowner.

Spray Foam

Spray foam is highly flammable. It must be covered by a 15-minute thermal barrier, according to the International Residential Code (IRC). A thermal barrier is a recognized material such as gypsum sheetrock that delays the underlying foam from catching on fire. Concealed spaces such as a crawl space may be exempt from this, depending on local building codes.

An insulation specialist spraying foam insulation to the wall

Foam Board

Foam board insulation, similar to spray foam, also requires a 15-minute thermal barrier as fire protection.

Fiberglass Roll (Or Batten)

Fiberglass itself is actually not a fire risk because it is not flammable. But most fiberglass is sold with a foil or paper facing - and that can burn easily. For that reason, most fiberglass roll insulations are typically not to be exposed as per building codes.

What Type Of Insulation Can Be Left Exposed?

Per the IRC, fiberglass insulation can be left exposed only in one of three scenarios:

  • It has been installed so that the paper facing is placed against the inside of the wall (against the sheetrock or other building material). This meets building code standards, as the flammable facing is no longer considered exposed. However, this is not always compatible with the best installation practices (the paper is a vapor barrier meant to face the inside of the house).
  • It has no paper facing at all.
  • Fiberglass can be left exposed if it has a special flame-resistant foil facing.

In all other settings, fiberglass insulation must be covered by a thermal barrier, the same for spray foam and foam board types. It is important to note that, while this is accurate for the IRC (which is the standard), local building codes can vary and may be stricter.

A newly constructed wall with fiberglass insulation

While fiberglass can technically be exposed and remain code-compliant, there are numerous health concerns with doing so. Physical contact with fiberglass insulation and inhalation of fiberglass dust can both be problematic.

Is It Bad To Breathe In Insulation?

There are a number of risks to inhaling both fiberglass or spray foam insulation. The only insulation that has no known respiratory concerns related to exposure is foam board.

Spray Foam

Spray foam insulation is full of chemicals that can be inhaled. There is data indicating that chemical exposure during a typical installation exceeds the limits set by OSHA. Dust released into the air during any cutting or trimming of the foam also contains chemicals. Exposure can cause asthma and other lung and respiratory problems.

Spray foam should always be installed by a professional due to the risks of this exposure. It is often recommended that the home be vacant for at least 24-hours after the spray has been installed. After this time period, spray foam is considered cured and relatively stable unless heat is applied (though there are individual reports where off-gassing continued outside of this timeframe).


Fiberglass particles can be inhaled into the airway or even the lungs. Direct contact with fiberglass insulation can cause sneezing, coughing, and itching. People with asthma or bronchitis may find their condition worsened by exposure to fiberglass particles. Airborne fiberglass particles can irritate the eyes, skin, nose, and throat. Current studies do not indicate a long-term risk of cancer relative to fiberglass exposure.

Can You Touch Insulation With Bare Hands?

Fiberglass and spray foam insulation can both cause skin irritation if touched. Spray foam is less likely to cause irritation or skin dermatitis than fiberglass. The extent of irritation varies based on the individual.

A woman applying ointment due to exposure of fiberglass insulation to her hands

Spray foam is also tough to remove from the skin if it dries. Do not touch uncured spray foam, and if accidental contact occurs, wipe it off immediately.

A condition called sensitization can occur with exposure to spray foam, in which a person develops an allergy after contact that they did not have prior. Physical contact may even lead to asthma attacks if sensitization has occurred.

Once cured, spray foam poses a minimal risk by contact. It only releases the chemical (isocyanates) that causes irritation if it is heated, cut, or burned. Fiberglass is always a potential irritant - it does not cure or become inert like spray foam, and is never safe to touch. Foam board, again, is the only insulation that seems safe for physical contact.

How Can I Easily Cover Insulation?

Since there are reasons never to leave any type of insulation exposed, what kind of solution is there? Many homeowners are looking for something cheap and easy, and aren't too concerned with beauty in an unfinished basement. Two fixes can cover the insulation with relative ease.

Plastic Sheeting

Plastic sheeting can be stapled over fiberglass insulation. This will help contain fiberglass dust particles and prevent accidental contact (especially if there is any chance a child could reach the insulation). Be sure to staple to the wood frame. Select one that is at least 6-ml thick, like this one by Husky.

Click here to see Husky Plastic Sheeting 6-ml on Amazon.

Gypsum Sheetrock

Install 1/2-inch (or thicker) gypsum sheetrock. This works for any insulation (for spray foam and foam board, plastic sheeting is not an acceptable solution as it is not a flame-resistant material).

Other options may be available, depending on your local building codes. There are other materials available that may meet the criteria for thermal barriers. Local building codes vary as to which ones they consider acceptable.

Does Covered Insulation Trap Moisture?

In some cases, insulation has been left exposed as a deliberate choice due to moisture concerns. Some people are afraid that sealing insulation behind plastic sheeting or drywall will trap moisture. This can grow mold and mildew, particularly in basements, where moisture and humidity are already typically high.

Fiberglass insulation is especially prone to moisture, whereas foam board is fairly resistant (spray foam falls somewhere between the two, depending on the type of spray foam). If you see that your insulation is becoming damp or damaged by water, you will want to address the underlying issue causing this. Insulation loses effectiveness once it has become wet.

You may want to install a dehumidifier to prevent mold, mildew, and other water-related issues. Be sure to select a basement dehumidifier for maximum effectiveness, instead of a whole-house version.

In summary

Insulation poses risks as both a fire and health hazard. Health concerns include respiratory and lung ailments and contact dermatitis. For these reasons, insulation should always be covered as dictated by your area's building codes, with sheetrock or another approved material.

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