Not necessarily. If you do not install insulation and if condensation is not a problem, then a vapor barrier under a metal roof is unnecessary. However, if you do insulate your metal roof, a vapor barrier is an essential addition.

Do you need a vapour barrier with Styrofoam insulation?

Foam insulation usually does not require a vapor barrier. For some foam insulation types, such as closed-cell spray foam and foam board insulation, the insulation itself stops the movement of most water vapor.

What is the best insulation to use under metal roof?





Spray Foam

  • It’s one of the most effective options for metal roofing, and it’s very easy to work with.
  • It can be installed on old or new metal roofs without causing disruption or the need for reroofing.
  • Since it’s self-adhering, it’s an excellent option to insulate awkward-shaped areas.

Can rigid foam be used as a vapor barrier?

Rigid foam board, especially foil-faced polyisocyanurate, creates a vapor-impermeable barrier, so the wall would have limited drying potential. Even more permeable types of insulation, such as expanded polystyrene, are vapor barriers when the installation is thick enough.

Can I use Styrofoam as insulation?

Styrofoam is also a material that has great insulating properties.

Where should you not use spray foam insulation?

When NOT to Use Spray Foam Insulation

  1. For areas that are too close to electrical boxes:
  2. For areas too close to ceiling light boxes:
  3. Open-cell spray foam on your roof:
  4. For closed-cavity spaces:
  5. If you have a history of skin, respiratory, or asthma problems:




Is vapor barrier necessary?

A vapour barrier is an important component in building construction. Its purpose is to help prevent water vapour from reaching building walls, ceilings, attics, crawlspaces or roofs, where it can condense and cause building materials to rot or grow mould.

Do you need a vapor barrier under a metal roof?

Without one, water can get trapped in the wall, which will produce moisture and ultimately other issues like rot, mold, and trouble with thermal performance. Vapor barriers are recommended for under metal roofs.

Does metal roof need moisture barrier?

To avoid condensation buildup with your metal roof, you will need to have a moisture barrier in place. When the air in the home is warmer than the air outside, condensation will collect. If the roof system is not ventilated properly, condensation can also collect.

Can you put insulation under metal roofing?



Yes, providing a layer of insulation under a metal roof is imperative because metal is naturally a better heat conductor than wood. Quality insulation helps a home retain heat in the winter and keep cool when the temperature dips.

Can you insulate a house with Styrofoam?

Because of its resistance to moisture, foam board insulation is a great choice whenever and wherever there is a chance it could get wet, such as: an exterior foundation, inside a basement against the foundation, and on the outside of a house beneath a house wrap.

What is a better insulator than Styrofoam?

Along with insulating more effectively than currently used materials like Styrofoam, nanowood is also stronger, and it won’t cause the same lung irritations that fibers from glass wool insulators do.

Is Styrofoam the best insulator?



Air is fine at convection, but the heat transfer is minimal because the low mass can’t store much amount of heat. Thus it blocks the flow of the heat energy. Styrofoam reduces conduction and convection. In this way, it is one of the best existing insulators.

How thick should Styrofoam insulation be?

Now generically speaking, we usually recommend open cell spray foam to be 6- to 10-inches on a roof deck or ceiling and 3-inches in the walls. Closed cell spray foam should be 4- to 5- inches on the ceiling and 2- to 3-inches in the walls.

What R value is Styrofoam insulation?

How does it work? Resistance to the flow of heat is measured in “R-value”, the higher the R-value, the harder it is for heat to get through. STYROFOAM extruded polystyrene insulation is rated at an R-value of 5.0 per inch at 75°F.

What is Styrofoam insulation?

Styrofoam™ Brand Square Edge Insulation* is an extruded polystyrene foam (XPS) insulation board that meets the needs of the commercial foundation and building floor slab market and can also be used for attics, foundations/slabs and crawl spaces in residential applications.

Is Styrofoam water resistant?



Styrofoam insulation can be water-resistant, but it is not entirely waterproof. While this material does not absorb moisture from the air, it can absorb water it comes in direct contact with.

Does Styrofoam insulate cold?

Much like wrapping up in layers of clothing helps you stay warm during cold weather, Styrofoam keeps items cool by insulating them against heat.

Is XPS foam the same as Styrofoam?

Styrofoam is a trademarked brand of closed-cell extruded polystyrene foam, or XPS. This foam is also referred to as “Blue Board” and is used for building insulation, thermal insulation and water barriers.

What is polystyrene vs Styrofoam?

Polystyrene is a common polymer material produces from the monomer, styrene. Styrofoam is a form of polystyrene. The key difference between polystyrene and Styrofoam is that the polystyrene is a form of synthetic aromatic hydrocarbon polymer whereas the Styrofoam is a commercial brand of polystyrene.

What is the difference between EPS and Styrofoam?



As we said, Styrofoam™ is a Dow trade, blue in color, and is an extruded polystyrene (XPS) foam made for thermal insulation, construction and craft applications. EPS is an expanded polystyrene available in various densities for insulation, construction and craft applications and so much more.