Performance Information for
Reflective Insulations and Radiant Barriers
Air Space Requirements Per User / Per Application
(Click on the pdf below to find the Air Space Requirement for your application.)
DIY Air Space Requirements (Revised 1011).pdf
Reflectix is the Industry Leader! We manufacture the highest quality, most extensively-tested, readily-available, reflective-based insulations and radiant barriers in the world! With Reflectix® products, there is no middleman. We are the manufacturer and we operate with an ISO 9001:2008 certified management system. Our testing and validation requirements are second to none. Distribution of our products is worldwide through Do-It-Yourself Retailers, Contractor Sales Groups and Industrial/Commercial Building Product Suppliers.
Ease of installation and diversity of applications are two major advantages. Reflectix® Insulations and Radiant Barriers are very easy to handle and install. All that is required are simple hand tools and access to the installation area. Reflectix® products are some of the most diverse, energy conserving building materials available, with over forty verified applications for residences, industrial/commercial buildings and agricultural structures.
These are 3 ways that heat moves from warm regions to cool regions:
Conduction: Heat flow through a material
Convection: Heat flow transferred by the movement of air
Radiation: Electromagnetic transfer of energy through space
Both products contain the same metalized aluminum and can be utilized as reflective insulations or as radiant barriers. The key difference is in the structure. The Reflective/Bubble products have strength and substance (from the bubble) that are ideal for a wide variety (40+) of applications (Residential and Industrial/Commercial). The Reflective/Scrim/Reflective Radiant Barrier product is designed primarily for residential attic applications as a radiant barrier.
Our tape is used to join the ends of the Reflectix® Reflective/Bubble Insulation products. It ensures a continuous reflective surface, and prevents air leakage that can result in condensation.
Reflectix® Reflective Insulation, Radiant Barrier and Foil Tape can be installed in environments with a range of -60 degrees to 180 degrees F.
Reflectivity is a material “characteristic” that is quantified as a percentage of radiant energy that a material will reflect.
Example: The reflectivity of the metalized aluminum in Reflectix® products is very high (94% +). This makes for very efficient performing reflective insulation assemblies (quantified in R-values).
A reflective insulation is a material (or assembly) that reduces the rate of radiant heat transfer across air spaces by use of one or more highly reflective surfaces. This rate of heat transfer can be quantified for a specific application by an R-value.
For either a reflective insulation or a radiant barrier, an air space of a minimum thickness is required on the reflective side of the product. (Most Reflectix® products are reflective (shiny) on both sides.) The reflective insulation benefit is derived from the interaction of the highly reflective surface with the air space. If the reflective surface is in contact with another building material, it becomes a conductor (transmitting the energy by conduction). An air space may be specified on one or both sides of the product (always on a reflective side). Enclosed air spaces, when instructed, are required to provide the stated R-value.
In the same (primary) way fiberglass or other mass insulations provide benefit, reflective insulation reduces conductive heat transfer. When a highly-reflective material (such as our product) is installed in a building assemblage, in conjunction with an air space, it provides a quantifiable R-value level of benefit.
An R-value is an assigned number derived from a specific testing procedure (or calculation) to determine a materials (or building assemblage) “resistance to conductive heat transfer”. The higher the R-value, the more resistant a material (or building assemblage) is to conductive heat transfer. Reflectix® can provide verification for all R-values stated for all products and applications.
All materials have a “conductive heat transfer”. Some are very high and some are very low. Materials that are low (or resistant) to heat flow have higher R-values.
Example: If a heat lamp is positioned shining on a 0.5” (width) panel of plywood (R-0.62), within a very short time, the opposite side of the panel will become hot to the touch (the wood has transferred the heat from one side to the other). -- Position the same heat lamp an equal distance from a batt of fiberglass (R-19). It will take dramatically longer to detect any increase in temperature on the opposite side of the batt (if at all). The difference in R-values indicates which material has the best “resistance to conductive heat transfer”.
R-values for reflective insulations are dependent on two (primary) criteria:
1. Heat flow direction
2. And, the amount of air space in a closed cavity on the reflective side of the product in a building assemblage
This is the reason our product has different R-values for different applications (varying amount of air space and heat flow directions).
These terms are related to heat flow directions. They are a part of the criteria utilized in R-value testing. For example, when testing a floor assemblage, heat flow down is tested. When testing for a wall system, heat flow horizontal is tested (same for all conductive heat transfer insulations).
Calculated R-values consist of three factors (individual resistances added to get the total resistance):
1. Interior “air film” (when present)
2. Substrate R-value
3. Enclosed air space R-value (on one or both reflective sides of the product)
Reflective Side of Product:
• R-4.55 Down
• R-1.32 Up
• R-1.70 Horizontal
White Side of Product:
• R-0.92 Down
• R-0.61 Up
• R-0.68 Horizontal
“Air space” requirements (on one or both reflective sides of the product) are specified in the installation instructions based on the building components of the application (which create the air space required within the assembly). Also, the product labels and the website (please refer to the pdfs at the top of this page) contain additional specifications on enclosed air space requirements.
The R-value for fiberglass mass insulations originates in the density, thickness and the physical composition of the material.
Example: A 3.5” thick batt of fiberglass can be designed to have an R-value of 11. It can also be manufactured to an R-value of 13 by increasing the density of the fiberglass (same width of 3.5”).
One component that affects the R-value of a specific product (or assembly) is internal convection. The primary reason that fiberglass does not produce different R-values when tested up or down, is that fiberglass (batts) do not exhibit internal convection. Where within a reflective insulated assembly, the convective component influences the amount of heat transferred based on direction (up or down).
With multiple layers of product and airspaces between each layer, enhanced performance will be gained. If the product is simply “doubled” (with no air space between the layers), a very minimal benefit is obtained (R-1.1 (per layer) for the Reflective/Double Bubble product).
Spacers are used to provide an air space where one is not present.
No Air Space = No Reflective Insulation Benefit
(An R-1.1 is provided from the product itself for the Reflective/Double Bubble material.)
There are several. Here are some examples:
• Reflectix® Reflective/Double Bubble Insulation cut into 2” strips
• 1”x 2” Furring Strips
• Thermal Breaks (a building product similar to furring strips)
• Reflectix® Duct Spacers
Reflectix® has a Class A/Class 1 Fire Rating on our Reflective/Bubble Insulation. It also meets all fire and smoke safety requirements of federal, state and local building codes (Satisfies UL 723, NFPA 255 and UBC 42-1).
An example of this would be the hot sensation you feel on your skin when walking from shade into direct sunlight.
Emissivity is a material “characteristic” that is quantified as a percentage of radiant energy that a material transmits.
Example: The emissivity of the metalized aluminum in Reflectix® products is very low (5%). This quality makes for excellent radiant barriers.
Radiant barrier is a material that is a poor re-transmitter of infrared waves (radiant energy). By definition, this re-transmission characteristic (emissivity) must be at or below 10%. The emissivity of Reflectix® products is approximately 5%. Therefore, when a radiant barrier is installed in a residential attic, it “blocks” 95% of the radiant energy that is being radiated by the hot roofing materials. This equates to a cooler attic, resulting in a house that requires less air conditioning usage to maintain comfortable inside temperatures.
Example: Plywood has a very high emittance (82%). This is the reason attics are so hot during the day. The shingles are heated by the sun and (by conduction) the heat is transferred to the plywood decking which in turn emits (radiates) 82% of this energy to the interior of the attic.
Low emissivity sheeting (as in our Reflective/Scrim Radiant Barrier) has a very low emittance (5%). This is the reason when a low emittance sheet is installed below a roof (plywood decking) in an attic that such a substantial reduction in radiant energy occurs.
For either a reflective insulation or a radiant barrier, an air space is required on the reflective side of the product. (Most Reflectix® products are reflective (shiny) on both sides.) The radiant barrier's benefit is derived from the interaction of the low emittance surface with an air space. An air space must exist on a minimum of one side of the product (always on the reflective side (residential attic - preferably oriented facing down)). Radiant barriers by definition do not require an enclosed air space to provide benefit. This application (radiant barrier) is typically installed in a ventilated attic.
The product has a very low re-transmission rate (emissivity) of radiant energy. It blocks 95% of the radiant energy that it encounters and this translates to a significant reduction in attic surface temperatures. A cooler attic results in a cooler house requiring less air conditioning usage.
A savings of up to 10% off your air conditioning usage are typical. This can be a larger number if there are ducts mounted in your attic space.
No. R-values describe the rate at which energy is transferred through a material or assembly. Radiant barriers provide benefit by dramatically reducing “radiant” heat transfer which is just as significant but not related to an R-value type performance.
No, absolutely not. There has been significant testing on this issue and it has been proven that a radiant barrier installed in a residential attic will have not have any detrimental effect on the shingles.
No, ventilation is not required, but it is extremely helpful when addressing convective heat transfer. If an attic system has a mass insulation (such as fiberglass), a radiant barrier and a ridge vent, it has addressed three types of heat flow; conductive, convective and radiant within that system.
Dust only comes into play when the product is installed in blanket fashion on the floor of the attic. Dust should be removed periodically for the product to maintain its effectiveness. Installations with the product on the roof deck or underside of the rafter require no maintenance.
Reflectix® has a Class A/Class 1 Fire Rating on the Reflective/Scrim/Reflective Radiant Barrier meeting all fire and smoke safety requirements of federal, state and local building codes. (Satisfies UL 723, NFPA 255 and UBC 42-1.)