There are dangers: The toxicity of fumes released during fires, as described by Mazura. Raising the ire of local building inspectors. It may be a code violation to install any foam board (eps, xps, poly iso) against interior walls without a fire barrier.

Does polyiso need to be covered?

Yes, polyiso roof insulation, like other roofing materials, should be protected from environmental conditions when staged on a job site and during installation. This is essential to ensure that the installed roof system is not compromised by moisture or other elements.

Do you have to cover foam board insulation?





Tests have shown that these laminated boards can withstand UV ray damage for a reasonably long time. That said, it’s still advisable to cover any foam board insulation exposed to the Sun within 30-60 days at the most. On most projects, that’s more than enough time to finish the exterior walls.

Can polyiso be exposed?

The requirement is more stringent for foam plastic products used in exterior walls of Types I – IV where they must meet a flame spread index of 25 or less. Polyiso will not melt or drip when exposed to fire.

Is polyiso Board toxic?

Polyisocyanurate (Polyiso)



Halogenated flame retardants are considered a very high concern to avoid because they can be persistent and toxic.

Is foam insulation board toxic?

Most rigid polystyrene foam insulation boards, both the EPS and XPS types, contain the toxic flame retardant HBCD, which was banned by the European Union in 2015.

Can you drywall over rigid insulation?





Drywall, which is actually a mineral called gypsum, resists fire. It also helps insulate and soundproof the room. The most common way to hang drywall over rigid foam insulation is to glue and screw it into place.

Can you leave rigid insulation exposed?

Q. I plan to install rigid foam insulation in a crawlspace. As far as I know, most types of rigid foam insulation can’t be left exposed, but need to be covered with a layer of drywall for fire resistance.

Can I leave insulation exposed?

Fiberglass insulation should never be left exposed in an occupied area, according to the American Lung Association,” says ALA’s Godfrey. “Exposed fiberglass insulation, once in the air, does cause respiratory reactions, such as dry, scratchy throat and coughing, as well as acting as a skin and eye irritant.

Does polyiso offgas?

Typical current blowing agents for polyiso are CO2 and pentane. There is some “thermal drift”, meaning the blowing agents offgas over time. The offgassing is extremely minimal. This is going to become a very common exterior insulation as building codes move towards requiring exterior insulation.

Can you use polyiso for walls?



Made of water-resistant rigid foam sandwiched between two protective facers, polyiso insulation is commonly used on commercial and residential roofs and walls because of its high R-value per inch of thickness, its capacity to serve as a vapor retarder, low water absorption, high compressive strength and durability, and

Does foam board insulation off-gas?

Does spray foam insulation off-gas? The quick answer to that question is yes. When contractors talk about off-gassing, what they’re talking about is the VOCs that cause the off-gassing.

Do you need a vapor barrier with foam board insulation?

Vapor barriers are often installed in basements and crawl spaces to prevent ground moisture from leaking in. In houses with spray foam insulation, however, vapor barriers are not necessary.

What is the safest insulation to use?



Compared to fiberglass insulation, any of the above options would be safer than insulating your home with tiny glass shards dipped in formaldehyde. However, the safest option of all is cellulose.

Can you layer polyiso insulation?

Multiple layering of the polyiso can add to the benefits of a multi-layered system in both fully mopped systems and systems that have the first layer of insulation mechanically fastened with successive layers mopped or adhered.

What happens if Polyiso gets wet?

Polyiso foam board, which also has a closed-cell structure, doesn’t absorb water; hence it can be wiped down. A dehumidifier or fans placed against the wet area can also hasten the drying process. Essentially the extent to which the foam board is wet will determine whether you’ll remove the foam boards to remedy it.

How do you attach Polyiso?


Quote from Youtube video: There are a number of fasteners that you can use to attach the poly iso insulation to your project. You can use a galvanized roofing nail a sixty ring shank nail with a plastic washer.

How do you install rigid foam insulation on interior walls?



How to Install Rigid Foam Insulation Between Studs

  1. Measure the Project Area. Measure the entire wall area to figure out the amount of rigid foam to purchase. …
  2. Measure Individual Cavities. Measure each bay individually. …
  3. Mark and Cut the Rigid Foam. …
  4. Install the Rigid Foam Insulation. …
  5. Seal the Gaps in the Insulation.


Can you use insulation board instead of drywall?

Instead of using a more complicated or expensive alternative, such as decorative fiber cement boards, fiberglass panels or magnesium oxide (MgO) board, consider insulating your drywall with engineered EPS foam panels, such as InSoFast UX 2.0, particularly in a moisture-prone basement.

How do you cover rigid foam insulation?

The most common approach is to apply a stucco-like “parged” finish with a surface-bonding cement. These finishes range from a thin paint-on coating to a thick acrylic-modified mortar applied over hardware cloth or metal or fiberglass lath. The thin paint-on coatings are easily chipped and prone to peeling.