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Thicker R-36 E.P.S. Insulation

The standard seven inch thick expanded bead polystyrene insulation (E.P.S.)  in the American Ingenuity 27' thru 60' domes can be upgraded to nine inch thick E.P.S. The 22' dome which has 3 1/2 inch thick E.P.S. can be upgraded to seven inch thick E.P.S. See the bottom of this page for the prices.  Please, scroll down the page to read detailed data and characteristics of E.P.S. insulation.

Ai only recommends 9" (R-36) thick insulation for areas where the high temperature does not get above zero degrees for five days in any given year. Our dome with 7" E.P.S. will easily outperform conventional housing with 11" thick fiberglass insulation. If you are not in the zero degree areas instead of purchasing thicker insulation from us put that money towards double or triple paned windows and insulated doors; as windows and doors are where your cooled or heated air will escape.

E.P.S.- Expanded Bead Polystyrene Insulation

E.P.S. is frequently, mistakenly, referred to as “Styrofoam”. Although they both come from the same “base” material, polystyrene, the two products differ in many respects. “Styrofoam” is the registered name of Dow Chemical Co. and refers to the extruded polystyrene insulation product produced and marketed solely by that company. “Styrofoam” is generally blue in color and has a minimum density of about 1.80 pounds per cubic foot. It has a different cell structure (like hollow bubbles) and has a marginally lower better R value, but is considerably more expensive, not only per board foot but even more so on a “cost per R” basis. E.P.S. is available from more than 100 manufacturers throughout the country in a variety of sizes, densities and forms. “Styrofoam” is only available from one company in a more limited range of sizes.

Seven inches of sturdy, rigid R-28 expanded polystyrene (E.P.S.) foam insulation forms the core of each American Ingenuity component panel. (Except the 22' dome has 3 1/2" thick E.P.S.) This insulation is permanent, chemically and thermally stable, resistant to mildew, provides no nutritive value to animals, plants, microorganisms, is non-irritating to skin, and is Chlorofluorocarbon (CFC) and formaldehyde free. This E.P.S. insulation will not rot, shrink, absorb moisture, compact, or deteriorate due to age or weather. It also acts as a vapor barrier for your home, providing stable performance year after year.

The E.P.S. that Ai uses is sometimes referred to as bead board and sometimes incorrectly referred to as Styrofoam (Styrofoam is the trade name for extruded polystyrene manufactured by Dow Chemical Co). Ai does not use Styrofoam.

American Ingenuity uses the one pound per cubic foot density, closed cell E.P.S. which has a thermal resistance (R-value) of 4.17 per inch of insulation at near freezing temperatures. This also explains why it is a very common insulation used in housing and sold at hardware stores. Ai uses the 7” thick E.P.S. which has an R-value of about 28.

Ai chose the expanded polystyrene over the extruded polystyrene because the extruded polystyrene is almost twice the cost with only a slightly better R-value.

When should you purchase the 9" thick E.P.S.? If you have five or more days a year where the temperature reaches zero degrees then you may want to purchase the thicker 9" insulation. If you have hotter days than most climates, we leave it up to you whether you need the 9" thick E.P.S.. On the price list go to the Building Options and look down the list for 9" Insulation.

Ai does not recommend that you purchase the 11" E.P.S. insulation unless you live in a severe climate like the Northwest Territory of Canada.

Insulation Comparisons:

  • 2x4 solid wood with 3 1/2" fiberglass is about R-8.
  • 8" Concrete Block, with 3/4" air, 3/4" Celotex is about R-9.
  • 2x6 Solid wood construction with 5 1/2" fiberglass is about R-11.
  • 2x4 solid wood with 3" urethane is about R-13.
  • 7" E.P.S. insulation is R-28 and is comparable to 11" of fiberglass insulation.
  • 9" E.P.S. insulation is R-36.
  • 11" E.P.S. insulation is R-44.

Remember, American Ingenuity's component panels for the 27' thru 60' domes includes the R-28 insulation and most of the steel reinforced concrete exterior finish and all the interior shell wall board. Typically, in wooden domes you will likely have to purchase the insulation, wall board and roofing materials for extra costs.

2010 Costs For Thicker E.P.S. Insulation

 The above pricing is for the following:

  • To upgrade the 22' dome from 3 1/2" E.P.S. to 7" thick E.P.S.
  • To upgrade the 27', 30', 34', 40', 45', 48' and 60' dome from 7" thick E.P.S. to 9" thick E.P.S.

If you upgrade your 48' or 60' dome with 9" EPS more semi-trucks will be needed for delivery.  The 48' kit will require two trucks and the 60' kit will require three trucks for delivery.

Q: Why are your dome homes so energy efficient?
You can save 50-70% on heating and air-conditioning costs with your American Ingenuity dome over a conventionally built home. Some of the reasons for this superb energy efficiency are:

  • Super insulation that does not degrade with time, moisture, or compaction.
  • Spherical shape means reduced exposed surface.
  • Airtight exterior virtually eliminates energy leakage.
  • Solid thermal envelope.
  • Uniform R-value. The insulation is not interrupted with structural members (e.g. 2X4's roof trusses). The only breaks are for doors and windows.
  • Downsized heating and cooling equipment.

Your kit comes with lifetime R-28 E.P.S. insulation (22' with R-14), or if you choose, thicker R-36 E.P.S. insulation is available. Even in cold climates, you may find that a single ventilating wood stove can heat a smaller dome (22', 27', 30' or 34') will provide all the heat your home will need. Larger domes need a centralized ducting system to disperse the heated or cooled air through out your dome.


The Expanded Bead Polystyrene (E.P.S.) Insulation that American Ingenuity utilizes is seven inches of sturdy, rigid R-28 modified E.P.S. insulation which forms the core of each component panel. The E.P.S is one pound per cubic foot density (pcf).

The E.P.S. insulation will not rot, shrink, absorb moisture, compact, or deteriorate due to age or weather. It also acts as a vapor barrier for your home, providing stable performance year after year.  The E.P.S. is:

·         permanent

·         chemically and thermally stable

·         resistant to mildew

·         provides no nutritive value to animals, plants, microorganisms

·         non-irritating to skin

·         Chlorofluorocarbon (CFC) and formaldehyde free.

What kind of vapor barrier will American Ingenuity dome have?  Approximately one quarter of the energy consumed by an air conditioner is used to extract water vapor from inside the house. Water vapor easily passes through most building materials and is readily swept into homes through joints, seams and through the attic. The E.P.S. insulation that Ai uses provides a good vapor barrier.   And the Ai building system provides for an air tight house.

During the US Dept of Energy Study on energy efficiency in  housing designs, the blower door test showed the American Ingenuity dome to be 56% tighter than the conventional test structure and 29% tighter than the Dow house.  To see if air was passing through walls of the dome, tests using infrared were performed. Thermal irregularities in the dome were shown to be insignificant.

Per the manufacturer of the E.P.S. that American Ingenuity uses, "the E.P.S. is closed cell and will not absorb more than 2.5% of water based on volume".  E.P.S. is often used as flotation for docks because it will not absorb water. 

Per E.P.S. manufacturer's data sheets the following description was given to explain how the E.P.S. is affected by Moisture:  "To retain their original insulation value, all insulation materials must remain dry.  Water is a good conductor of heat so a high moisture content in the insulation results in a significant loss of performance.  This is particularly so with fibrous materials which must be positively protected by an efficient vapor barrier.  There are two ways in which moisture can affect insulation materials: water absorption from contact with damp surfaces or rain penetration or from interstitial condensation of water vapor.  E.P.S. is a closed cell material and has minimal water absorption and low water vapor transmission.  Both of these properties are to a large extent, density related, but also to the degree of fusion of the material.  Tables 4 and 5 show typical performance figures for good quality E.P.S. boards manufactured to Arco Polymers recommendations.”           

Table 4  Water Absorption

Density (pcf)                                  1.0 lb                            1.5 lb                             2.0 lb
(pounds per cubic foot)

Water absorption (% vol)        less than 2.5                  less than 2.0                  less than 2.0


Table 5 Water Vapor Transmission (WVT)

Density (pcf)                                                     Grains (hr/sqft) In/Hg (Perm inch)

1.0                                                                                            1.2-2.2

2.0                                                                                            0.6-0.8

2.5                                                                                            0.5-0.7

3.0                                                                                            0.5-0.7

The amount that a material will breathe is measured in perms or sometimes perm inches.

 “Note: FHA requirements for perimeter insulation are that the original K value of the material must not increase by more than 15% after repeated wetting and drying cycles.  Tests have been carried out on nominal 1.0 pcf density E.P.S. with an original K value (at 75 degrees F) of 0.26.  After submersion the K value was found to be 0.28--an increase of only 7.7%.”

 “Climatic Changes:  E.P.S. board has been used as an insulation material in various types of building structures for over 35 years in climatic conditions ranging from Arctic cold to desert heat and has performed satisfactorily.  E.P.S. does not become brittle at sub-zero temperatures (in fact its K value improves) and suffers no loss of impact resistance at -100 degrees F compared with 73 degrees F.  The maximum recommended continuous operating temperature is 175 degrees F.  Roof surface temperatures in Southern States may reach this temperature for short periods, but with suitably designed roof systems E.P.S. can be used under these conditions.”

In Ai's building system the water is stopped on the outside surface because the concrete is rich and dense enough to inhibit significant absorption and it is coated with a primer and two coats of good quality latex paint which further insures against leaks.  If a leak occurs the remedy is caulking and another coat of paint in that area...worst case elastomeric paint and stretchable fabric is used.  If and when any water gets past the concrete very little will be absorbed by the E.P.S. 


 Now this brings up breathability of the E.P.S.  The amount that a material will breathe is measured in perms or sometimes perm inches.  E.P.S. will breathe enough to allow it to dry out inside our walls.  At the same time it is tight enough to also serve as a good vapor barrier. Ai’s insulating concrete panel (ICF) is made from expanded polystyrene (E.P.S.) molded into lightweight foam blocks. The foam itself provides excellent insulation with an R value of R-24. The R-value of E.P.S. remains constant. (R-values of traditional fiberglass insulation decreases when the material is wet or damaged.)  Ai chose to manufacture its dome component panels with Modified Expanded Polystyrene (E.P.S.) foam because of its fire performance, structural performance, and environmental advantages.  Modified E.P.S. contains no formaldehydes or toxic chemicals, and uses fewer resources to manufacture than other insulation products.  E.P.S. provides you with superior thermal performance to better insulate your buildings, and no harmful CFC’s have ever been used to manufacture it.

You can now recycle your jobsite scrap through a network of manufacturers, re-processors, and retailers across the country. E.P.S. is a valuable resource than can be remanufactured into foam packaging or made into an amazing array of polystyrene products from office supplies to video cassette cartridges. 


Expanded Polystyrene (E.P.S.) Facts

E.P.S. is manufactured from expandable polystyrene beads containing a hydrocarbon blowing agent and a flame-retardant additive. It is a closed cell, lightweight, resilient, foamed plastic composed of hydrogen and carbon atoms. There are two common types of polystyrene foam, Extruded Polystyrene or X.E.P.S. (Popularly known by its Dow trademark, Styrofoam) and Expanded Polystyrene (E.P.S.). Both expanded polystyrene and extruded polystyrene are used extensively as thermal insulation in industrial, commercial and residential construction.

During the processing of E.P.S., steam heat softens the beads and causes the blowing agent to expand to produce moisture-resistant multi-cellular particles which increase in size up to 40 times their original volume.

Following a period of stabilization, during which time the beads loose their moisture, the blowing agent condenses out and air diffuses into their cellular structure, the pre-expanded beads are molded into blocks of insulation.

The benefits of E.P.S. thermal insulation products are its lightweight, has stable long term thermal resistance, no R-value loss over time (Source: 1985 Study conducted by Structural Research, Inc. for NRCA, MRCA, and SPI), and cost effectiveness when compared to other rigid board insulations on the basis of R-value.

Is E.P.S. a water, vapor or air barrier?

E.P.S. is considered water resistant and vapor permeable and at the density and thickness that American Ingenuity utilizes, the material acts as both a vapor retarder and an air barrier. This characteristic essentially moves the dew point to the exterior side of the concrete wall, minimizing interior humidity in the summer, and at the same time eliminates air infiltration in all seasons which is recognized as a major cause of R-value loss in fiberglass insulation. Air exchangers or heat recovery ventilation systems are highly recommended!

Is E.P.S. foam toxic?

E.P.S. is an inert, non-biodegradable organic plastic foam which will not rot and is highly resistant to mildew. According to National Bureau of Standards Combustion Tests, data collected from seven labs concluded that under the worst case fire scenario, fumes from E.P.S. are no more toxic than those from wood (Douglas Fir).

Is E.P.S. Flammable?

The requirements of all the major code organizations for foam plastics is that they have a flame spread of not more than 75 and a smoke development rating of not more than 450. The foam used in Ai’s component panels has a flame spread rating of 15 and a smoke development rating of 125 based on ASTME84-87 tests, well below the code requirements.



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