 The Dome Store > Dome Insulation Systems > Insulation Introduction and Options
Insulation Introduction and Options
Fiberglass Batt Insulation
The Natural Spaces Super-Wal dome system is designed as an ultra-super-insulated wall using fiberglass batt insulation with a minimum R-value of 47 and options for R-57 and R-67. If someone tells you there is a "point of diminishing returns", they haven't looked at today's and tomorrow's energy cost.When compared using the same R-value, fiberglass batts are 1/3 the cost of rigid polystyrene foam insulation or Icynene insulation and 1/5 the cost of sprayed-in-place urethane foam. Check with us for a cost saving comparison and the most up to date environmental info. Our installation methods and our use of industrial grade fiberglass reduce air infiltration dramatically, allowing an honest comparison of R-values with other insulation types.
Some dome companies claim they can get an R-35 using 2x4 construction. Building codes allow only a maximum R-value of 6.25/inch for figuring urethane foam-insulating values. Multiply that times 3 1/2” thick struts and you get an R-22.
Other companies also say that there are vastly diminishing returns beyond a certain R-value. Currently, the new minimum ceiling R-value for the northern tier of the U.S. is R-49. 25 years ago these same "authorities" were suggesting an R-19 ceiling. How will it change in the future? Why build a dome home with 2/4’s or 2x6’s that starts out 25 years behind the times?!
You actually pay substantially less for a Natural Space dome with an R-50value than you do for the competition’s dome with an R-30! We offer industrial type dense batts in various thicknesses of 6”, 8” and 9 1/2”. We put in 2 layers creating 12”, 16” and 19”. We also offer widths of 60”, 72” and 96”. This allows for one-piece triangles with no splices and quicker installation.
Not readily available in the residential market, we offer 60”, 72", and 96" wide rolls of insulation. This eliminates the joint lines occurring when using 24" wide batts. It also cuts down the installation time considerably. This seamless one-piece triangle insulation works extremely well in our Natural Spaces dome because we do not require all of the internal studs all of the other dome systems need. Our triangle spaces are wide open, just waiting for a full-size fiberglass insulation triangle.
Most of our insulation is made by Knauf. It is very stiff, fluffs out beyond the specified thickness, no formeldyhide, and has minimal residue. The insulation is cut on site using templates. We include a 6” knife, 2 filter masks and goggles. Fiberglass is made from recycled glass and waste slag.
Fiberglass batt insulation, we have found, is the safest and most economical type for our domes.
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| Dome Shell Insulation R-Values using Fiberglass |
| Dome Shell Thickness |
Vented Shell R-Value |
Insulation Thickness (Vented) |
Unvented Shell R-Value |
Insulation Thickness (Unvented) |
| 7 1/4" |
22 |
6" |
26 |
7 1/4" |
| 12 1/4" |
34 |
9 1/2 " |
43 |
12 1/4" |
| 15" |
47 |
13" |
54 |
15" |
| 18 1/4" |
57 |
16" |
64 |
18 1/4" |
| 21" |
67 |
19" |
73 |
21" |
| 24" |
76 |
22" |
83 |
24" |
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The basic insulation we use is industrial grade fiberglass. The air infiltration is minimal. The R-value chart uses an established value of 3.25/inch. Our insulation will perform at a higher number. The R-value numbers used in the chart include the entire wall/roof assembly of materials. |
Other types of insulation:
Icynene or soy based soft foam
Today, some foam insulation consists of materials similar to those found in pillows and mattresses. Also, most foam materials can now be used with foaming agents that don't use chlorofluorocarbons (CFCs) or hydrochlorofluorocarbons (HCFCs), which are harmful to the earth's ozone layer.
Some types of available liquid foam insulation materials include these:
- Cementitious
- Phenolic
- Polyisocyanurate
- Polyurethane
Some less common types include Icynene foam and Tripolymer foam. Icynene foam can be either sprayed or injected, which makes it the most versatile. It also has good resistance to both air and water intrusion. Tripolymer foam—a water-soluble foam—is injected into wall cavities. It has excellent resistance to fire and air intrusion.
Urea-formaldehyde (UF) foam was used in homes during the 1970s and early 1980s. It is no longer available for residential use because of health-related risk with formaldehyde.
Installation
Liquid foam insulation—combined with a foaming agent—can be applied using small spray containers or in larger quantities as a pressure-sprayed (foamed-in-place) product. Both types expand and harden as the mixture cures. They also conform to the shape of the cavity, filling and sealing it thoroughly.
Installation of most types of liquid foam insulation requires special equipment and certification. Therefore, you'll probably want a certified insulation installer to do it.
Following installation, an approved thermal barrier—such as drywall—must cover all foam materials. Also, some building codes don't recognize sprayed foam insulation as a vapor barrier, so installation might require an additional air barrier, like polyethylene or some other vapor retarder.
Costs
Liquid foam insulation products and installation usually cost more than traditional batt insulation. However, liquid foam insulation also forms an air barrier. This can help eliminate some of the other costs and tasks associated with weatherizing a home, such as caulking, applying housewrap and vapor barrier, and taping joints. When building a new home, this type of insulation can also help reduce construction time and the number of specialized contractors, which saves money.
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Sprayed Urethane Foam -
All closed-cell polyurethane foam insulation made today is produced with a non-CFC (chlorofluorocarbon) gas as the foaming agent. These foams have an aged R-value of R-6.5 per inch thickness. Their density is generally 2.0 lb/ft3 (32.0 kilograms per cubic meter [kg/m3]). There also are low-density open-cell polyurethane foams (0.5 lb/ft3 [8 kg/m3]). These foams are similar to conventional polyurethane foams, but are more flexible. Some low-density varieties use carbon dioxide (CO2) as the foaming agent.
Low-density foams are sprayed into open wall cavities and rapidly expand to seal and fill the cavity.
One manufacturer offers a slow-expanding foam, which is intended for cavities in existing homes. The liquid foam expands very slowly and thus reduces the chance of damaging the wall from overexpansion. The foam is water-vapor permeable, remains flexible, and is resistant to wicking of moisture. It provides good air sealing and yields about R-3.6 per inch of thickness. It is also fire resistant and won't sustain a flame.
Soy-based, polyurethane liquid spray-foam products are also available. The cured R-value is around 3.7 per inch. These products can be applied with the same equipment used for petroleum-based polyurethane foam products. |
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Rigid Insulation Board -
Rigid insulation board will work only if provisions are made for at least 1 1/2” of ventilation space between the outside sheathing and the insulation. Its R-value is twice that of fiberglass but its cost is four times greater |
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Cellulose, lamb's wool, natural cotton -
These insulation types are some of the other insulations currently available. We can help you figure out what’s best for you. |
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Click Here to see real time energy costs in domes using fiberglass and domes using soft foam.
Prices and Ordering
Insulation - Dome Shell
(No separate shipping cost when ordered as part of the dome shell package)
Insulation - Super-Wal Strut Fillers
Rigid Foam (Non-CFC) pre-cut pieces fit between the 2x8 outer strut and 2x4 inner strut to create a flat edge for the fiberglass insulation. Helps eliminate wind-wash & air infiltration. Sold in packs of 10.
(No separate shipping cost when ordered as part of the dome shell package)
Insulation - Standoff Spacers
Rigid Foam (Non-CFC) pre-cut pieces to hold insulation in place & maintain air space. Used on first row of triangles for high & mid profile domes only. Sold in packs of 10.
(No separate shipping cost when ordered as part of the dome shell package)
Venture Vapor Barrier Tape
Venture Sealing Tape is the one to use for sealing all the seams on your vapor barrier. Reduce leakage and achieve energy savings.
Independent tests by the National Association of Homebuilders show a 30% increase in performance when house wrap seams are sealed. (No separate shipping cost when ordered as part of the dome shell package)
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MemBrain™—The Smart Vapor Retarder.
Especially in climates with extreme seasonal fluctuations in climate and humidity,
there’s no foolproof way to keep moisture from getting into a wall. But now there’s
a revolutionary way to help get it out.
Designed to be applied over unfaced fiber glass insulation, MemBrain looks similar
to typical polyethylene sheeting, but is actually a polyamide-based material. But
what makes MemBrain unique is its ability to adapt its permeability depending on
climatic conditions.
With a high resistance to water vapor in winter or low humidity, MemBrain
behaves like a moisture vapor retarder such as poly sheeting. When the relative
humidity increases, its water vapor permeability increases dramatically. This allows
water vapor to escape the wall cavity easily when the humidity is high.
Click here for more information on MemBrain™
Standard rools are 12.33' x 100' (1233 sq. ft) $310 / Roll
(376 cm x 30.5 M = 114.7 sq. M) |
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