Perlite insulation R-Value Guide to Perlite-based Ceramic Insulation Products

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Ceramic building insulation for super high R-values: this article discusses the use in buildings of ceramic insulation, a variation on perlite insulation material produced by superheating.

Sketch at page top and accompanying text are reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss. Contact us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution.

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Q&A on Super High R-Value Insulation Products

The question-and-answer article below paraphrases, quotes-from, updates, and comments an original article from Solar Age Magazine and written by Steven Bliss.

Information on Ceramic Insulation Products for Buildings


We are about to re insulate our cathedral ceiling and have only the 2 1/2-inch dept of the purlins for insulation space. In September 1980 Popular Mechanics had an article on a ceramic insulation that claimed an R-value equivalent to 70 for 3 inches of thickness. Do you have any evaluation of this product? - Peter Slavish, New Hope PA


The ceramic insulation written up in the Popular Mechanics article is a variation on Perlite Insulation, an insulation that has been around for years. Perlite is made by heating silica ore to 1600 degF, causing it to expand. The ASHRAE Handbook of Fundamentals says expanded perlite with a density of 5 to 8 pounds per cubic foot has an R-value of 2.7 per inch. [See INSULATION R-VALUES & PROPERTIES].

P.D.I. St. Anne, IL, the manufacturer of the ceramic insulation discussed back in 1980 has patented a process for coating the perlite. The firm claims this boosts its equivalent R-value "in the radiant mode" into the R-70 range. A vented attic space and moving air above the insulation layer are needed for it to work. If the ceramic insulation is placed in a sealed space with no air circulation above it, P.D.I. says its R-value drops back to the "conductive" R value of 2.7 per inch.

In 1985 Solar Age contacted Oak Ridge National Lab in Oak Ridge, TN, for an expert opinion about ceramic insulation based on perlite. The lab's David McElroy said that thermal tests on ceramic insulation "indicate the material behaves very much like perlite, and does not have the high thermal resistance the manufacturers claim."

Oak ridge had insulation makes with accurate test facilities test the ceramic insulation. Their results came in at or below the Oak Ridge levels. National Research Council of Canada also confirmed these findings. Asked if the "radiant mode" explanation sounded plausible, McElroy said "No."

For an update on SUPER HI-R INSULATION including ceramic based products that do have very high R-values (and are very costly, hence used in special applications) see SUPER HI-R INSULATION.

Current High-R Building Insulation Products for Super Insulated Buildings

The high-R insulating panel building products currently in most common use
also polyurethane spray foam (URETHANE FOAM Deterioration, Outgassing).

These materials have a typical R-value of about R-5 to R-6 per inch, though when installed with a radiant surface (that might help) and a 3/4" air gap, the R-value is increased substantially - as we detail below. Fiberglass batts, which are still most-widely used in residential construction, are about R-3 per inch.

Here are some currently-available high-R building insulation products as well as some specialty very high-R insulation materials:

  • Aerogel has an R-value of about R-10 per inch, is 99% air and insulates up to 37 times higher R-value than fiberglass. The material is costly, and fragile, factors that have limited its use in residential construction. Work is in process to produce a less costly version.
  • Barrier Ultra-R super high-R building panels, produced by Glacier Bay, use Aerogel and are rated up to R-30 per inch, or in Barrier Ultra-r™ panels, R-50 per inch. The Ultra-R™ R-50 insulating panel is a rigid polypropylene-encased vacuum insulation panel that is custom made to the client's specified dimensions. The panels are also available with a fiberglass coating on one or both sides. (Used in refrigeration applications.)
    The company also produces acoustic panels that are Ultra-db resistant and lightweight. Unlike the appliance insulation panels discussed in the original Q&A above on miracle insulation, these Aerogel based panels will continue to retain some, though reduced insulating value if punctured, performing at perhaps R-9 per inch. The product is used in marine refrigerators, but in the future may be available as a residential construction product. The company is researching specialized products in medical, transportation, and aerospace applications.
  • Ceramic Insulation - version of high temperature treated Perlite Insulation
  • Eco-Panel polyurethane foam core structural insulated panels (SIPs) are produced by Eco-Panels Corporation. The 3-inch thick panels include structural elements and panel locking devices. The company offers a super-insulated 8.5-inch thick structural insulated panel and also produces roof panels. The 2.5 pound polyurethane foam used in these panels provides about R-7 per inch; 4-inch panels are rated at R-26, 6 1/2inch panels at R-40.
  • Hightherm R-24, Supertherm R30, and Superthermal R60 wall panels are produced by Supertherm. Wallpanel® uses 18 gauge steel studs spaced 16" on center, staggered to support 24" o.c. roof trusses, combined with high-density (two pound) polystyrene foam insulation. The higher density polystyrene foam insulation permits achieving an R-30 wall panel that is 6" thick (rather than 7" with lower density foam). The panels are finished with an insulating ceramic coating and are warranted for 25 years.
  • Low-E Housewrap Insulation™, is a patented insulation consisting of a closed micro-cell foam core that is heat laminated to foil or polyethylene facings. This foam board insulating product is thin, provided in rolls, intended as a thermal break wrap that is moisture, rodent, and insect resistant. The Low-E Manufacturer states that it outperforms 3-4" of fiberglass insulation. As the product literature points out, "All of these components are referred to as a system R-Value. A 3/4" air space facing the aluminum is ideal because convection currents cannot begin to move in an air space this small. The aluminum actually increases the R-Value of the air space it faces. Low-E is manufactured using a 1/4" polyethylene foam core with scrim reinforced double-sided aluminum facings. It can be used in all facets of the building industry where conventional insulations are used. It can be used alone or in conjunction with mass insulations for high R-systems. " The product is also advertised by some distributors for insulation retrofit products, attics, basements, under-slab insulation, etc.
  • Precision Panel R28 (R-4 to R-7 per inch) Laminated EPS foam core Structural Insulating Panels (SIPs) are produced by Precision Panel Co. located in Idaho, ships insulating panels world wide. The 4-inch thick EPS foam core panels are laminated with exterior sheathing (OSB) and an interior sheathing (OSB or ?). The foam core panels are prepared with window and door rough openings and accept edge splines or top and bottom plates for construction. They include wire chases and are cut to customer specifications.
  • STRAW BALE CONSTRUCTION has been considered a high-R building method for a long time and is discussed at STRAW BALE CONSTRUCTION
  • STYROFOAM™ Brand Spray Polyurethane Foam R 6.1 per inch, (CM Series) produced by DOW Chemical is a "two-component, spray-applied polyurethane foam that creates a seamless, monolithic barrier for protection against water vapor and air on the interior of steel stud walls. This closed-cell, 2-pcf spray foam successfully incorporates the Enovate 3000 blowing agent from Honeywell. This product is designed as a filler for the Thermax Wall System discussed below.
  • Super Therm® insulating ceramic coatings produced by Superior Solar Barrier, are used on buildings as well as freezers and refrigerators, intended as an impenetrable exterior coating. The coating uses a vacuumed microceramic hollow particle (ceramic bubbles) containing a gas,and providing minimal heat conductivity. The particles are distributed in a coating vehicle.
  • Thermax™ Wall System, DOW Chemical, "addresses design considerations for commercial steel stud applications and is not relevant for most residential applications. THERMAX™ Exterior Insulation R6.5 per inch, consists of a glass-fiber-reinforced polyisocyanurate foam core faced with nominal 4 mil embossed BLUE™ acrylic-coated aluminum on one side and 1.25 mil embossed aluminum on the other.
  • Tuff-R™ and Super Tuff-R™, Dow Building Solutions, have an R-value of R 6.5 per inch. Note that the R-value of this insulating board is increased to R-9.3 per inch if construction includes a 3/4" air space. These are closed-cell polyisocyanurate insulating foam core board products. The foam core is sandwiched between a choice of exterior faces including aluminum foil, tri-plex aluminum foil, or polyester kraft paper combined with reinforced aluminum foil. One board side is blue, the other is radiant aluminum foil. These products must be covered with a minimum of 1/2" drywall or equivalent thermal barrier in building applications. See POLYISOCYANURATE FOAM INSULATION. Also see Q&A on use of Rigid Foam Insulating Board. Also see the Dow Product Literature for Tuff-R insulating board - PDF file.
  • Vacuum Super-Insulated R-28 Panels from RParts are sold as an alternative to aerogel products. The panels are produced by a third party manufacturer using DOW INstill foam cores sealed at high vacuum in a special multi-layer gas impermeable barrier membrane film.

This article is reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss.

Here we include solar energy, solar heating, solar hot water, and related building energy efficiency improvement articles reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss.

Original Solar Age Magazine article on ceramic insulation

The link to the original Q&A article in PDF form immediately below is preceded by an expanded/updated online version of this article found above.

  • Q&A on Ceramic Insulation PDF version, Use your browser's back button to return to this page


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