Metal buildings commonly use either reflective insulation, fiberglass blankets, rigid foam, sprayed foam or a combination. Metal building insulation will meet the thermal and acoustical requirements for all types of pre-fabricated or pre-engineered steel buildings.

Steel is a very good conductor of heat. In hot weather, the steel structure will rapidly transfer the heat from the sun into the building. In cold weather, the steel will transfer the heat out of the building. Steel is also very susceptible to condensation. To avoid these problems, insulate your steel building with the proper insulation and/or a vapor barrier.

Insulating your metal building provides the following benefits:

• Heat flow. Metal building insulation controls the heat flow, acting as a barrier to decrease the amount of heat that comes in or goes out from your building structure, thereby reducing energy consumption.
• Noise. Steel conducts sound very fast. Metal building insulation improves noise control, reducing the sound transmission from the exterior to the interior of the building, and absorbs noise within the building.
• Condensation. Most metal building insulation comes with a vapor barrier facing, which provides condensation control, helping to prevent corrosion in its structural components and dripping from the ceiling.
• Lighting. Most metal building insulation has a laminated facing which can act as a reflector, increasing lighting efficiency.

White vinyl facing lightens & improves lighting effficiency.

Reflective insulation is the most commonly used insulation for metal buildings. Reflective insulation is used to maintain the natural temperature in metal buildings in both, warm and cold weathers. It is particularly recommended in warm climates where it reflects the suns radiant energy away from the building.

Reflective insulation is composed of two outer layers of aluminum foil and one inner layer of inert material. The inner material is used to create an air gap between the two layers of foil to trap convective heat as it rises. Some materials used for the inner layer are polyethylene, plastic and fiberglass. An inner layer provides more insulation power than foil alone with R-values as high as 14.5 per inch -- Details . When properly installed, foil also functions as a vapor barrier preventing condensation and dripping from the ceiling.

While traditional forms of insulation, like fiberglass, prevent heat by conduction and convection but have little effect on radiant heat, reflective insulation works by reflecting "radiant energy." Reflective insulation can reflect up to 97% of the radiant energy that strikes it. This feature is essential for keeping a stable indoor temperature by reducing unwanted heat loss or gain.

Unlike fiberglass, reflective insulation is not affected by humidity. This is a huge advantage for reflective insulation, as humidity will greatly decrease the effectiveness of traditional bulk insulation. Another advantage of reflective insulation over fiberglass is that it does not lose its effectiveness when it is compressed, and it does not irritate the skin, nose, or eyes, and as a result, it does not require special handling or clothing to install it.

Reflective insulation is commonly used in the walls and under the roof decking of pre-engineered steel buildings and pole barns.

Reflective insulation installed in metal buildings

The material most widely used for metal building insulation is fiberglass insulation. (Note: Fiberglass is not recommended in areas of high humidity - use reflective insulation instead)

Fiberglass can be unfaced or laminated on one side with a facing material that will act as a vapor barrier. The facing material is an important factor in fiberglass insulation. The different facing materials affect the workability (temperature conditions required for installation), permeability (rate of water vapor that the fiberglass can stand) and durability of the insulation. Polypropylene is the material most commonly used for facing fiberglass insulation.

The thickness of the blanket and the type of facing material will determine the efficiency of the fiberglass insulation. The heat flow will depend on the thickness of insulation, so the thicker the fiberglass blanket, the better it will hold heat inside the building.

Insulation System using Reflective and Blanket Insulation

When selecting the Fiberglass Metal Building Insulation that will fulfill your needs, you must consider the following:

• Facings

  Facing is the material used as as vapor retarder that covers one side of the fiberglass blanket. There are different kinds of materials used as facing. White vinyl and polypropylene are the most popular facings, and they satisfy the majority of applications.

• Tabs

  Tabs are part of the facing material that covers the side laps of the insulation. Tabs are used to seal the edge of the insulation blanket. Tab width may vary from 2 to 6". Tabs come in different sizes, varying by manufacturer, but 1-6" is the most common size.

• Thickness (R-Values)

  The effectiveness of a material as insulator is measured by its R value. The R value measures the resistance to convective heat transfer. The average R-value for fiberglass batt insulation is 3.2 per inch. The thicker the insulation, the higher the R-Value will be.

  Fiberglass thickness	Uninstalled R-Value
  2"	R-6.4
  3"	R-10
  4"	R-13
  6"	R-19

• Banding systems

  Banding systems are used when installing insulation to keep the fiberglass from sagging. You can band 2 or more layers of insulation together to get a higher R-Value.

Condensation can be a big problem in a metal building. A vapor barrier, also known as "facing", is usually made of plastic or foil sheeting that stands alone or covers one side of the insulation to keep the moisture away from the metal ceiling where it can condense and cause dripping, rust, mold, mildew and odors. The vapor barrier material is rated in perms by the amount of moisture that it will let pass through. The lower the perm rating, the more effective the vapor barrier is.

For metal buildings, the vapor barrier used should be strong, have good tensile strength and provide good rip and puncture resistance. In addition, the vapor barrier should be fire retardant, provide good reflectivity, be durable and have low permeance.

Vapor barriers come in a wide variety of materials. The table below shows a list of perm ratings for the most commonly used facings on metal building insulation.

Material used as vapor barrier	Typical perm rating
Vinyl	1.0
Aluminum Foil	0.001
Polyethylene (4-and 6-mil)	0.05
Polypropylene/Scrim/Kraft/Metallized Polyester (PSKP)	0.02

When the rating is higher than 1.0, the material is not considered vapor barrier. In building construction, experts recommend using a material with a perm rating of less than 0.9. Properly installed and sealed reflective insulation makes a perfect vapor barrier, making it very cost effective.

NAIMA
Metal building insulation applications information
http://www.naima.org/pages/products/mb.html

Metal Building Insulation
Selecting the proper metal building insulation for your needs
http://www.metalbuildinginsulation.com/insulation-options.htm

NIA
Metal building design & insulation installation.
http://www.insulation.org/metalbuilding/pages/design/design.html

SteelBuilding.com
Steel building insulation
http://www.steelbuilding.com/buildings/accessories_insulation.htm

NAIMA
Recommendations for installing fiber glass insulation in metal buildings
http://www.naima.org/pages/resources/library/pdf/MB316.PDF