wool01There are many natural insulation products available today, so why would you choose wool, or more specifically, sheep wool insulation products.

Since 8,000 BC, sheep have been able to adapt to even the harshest of environments; their wool protects them through hot, cold, damp and dry seasons. Because of their crimped nature, when wool fiber is packed together, it forms millions of tiny air pockets which trap air, and in turn serves to keep warmth in during winter and out in the summer.

The crimp in the wool fiber forces each strand to bump up against each other, as opposed to lining up side by side or laying down flat together. This keeps the tiny air pockets intact, acting as little insulators — the key to being able to keep you both warm and cool.

The unique advantage of wool as an insulator is the NATURE of the fiber.

  • It absorbs and desorbs moisture; it heats and cools as this process takes place. Wool therefore can absorb moisture in your house, preventing condensation.
  • It has plastic memory, not that there is any plastic in wool, but rather that technical description is used to explain the “crimp”; the ability to retain the shape it was in before it left the sheep.
  • The energy required to produce our insulation is less than 10% of that required to produce traditional insulation materials.
  • Wool can absorb and breakdown indoor air pollutants such as formaldehyde, nitrogen dioxide, and sulfur dioxide.
  • Wool is a sustainable and renewable resource; every year our sheep grow a new crop.
  • Wool is completely recyclable; at the end of its life as insulation it can be re-manufactured, reused, or biodegraded.
  • Wool is an excellent absorption medium of sound waves; its inherent qualities provide much more acoustic insulation than traditional insulation in similar applications.
  • While wool is generally fire resistant, our wool is treated with a 100% natural solution of organic materials that provide unequaled fire and vermin resistance. These materials are bonded chemically to the wool fiber, not merely “glued on” as in most other insulation products.
  • A material’s R-value is the measure of its resistance to heat flow. It is important to know the R-value because many states or regions require that a roof system have a minimum amount of thermal resistance on commercial, industrial, and/or institutional buildings. The way it works is simple: the higher the R-value, the more the material insulates.
  • Some common roofing materials and their corresponding values for Thermal Conductance (C) and Thermal Resistance (R) are shown in the following table.


In Inches

C-Value R-Value
Metal N/A 0.000 0.00
Concrete 1.0 3.333 0.30
Gypsum 1.0 1.667 0.60
Wood 1.0 1.099 0.91
Tectum 1.0 0.500 2.00
Inside Air Film N/A 1.087 0.92
Outside Air Film - Summer N/A 4.000 0.25
Outside Air Film - Winter N/A 5.882 0.17
Vapor Retarders N/A 0.000 0.00
BUR Gravel N/A 2.941 0.34
BUR Smooth N/A 4.167 0.24
Fiberboard 1.0 0.360 2.78
Perlite 1.0 0.360 2.78
Phenolic Foam* 1.0 0.120 8.30
Fiber Glass 1.0 0.256 3.90
Polyisocyanates 1.0 0.180 5.56
Polyisocyanates Composite 1.5 0.240 4.17
Polystyrene Bead Board 1.0 0.280 3.57
Polystyrene Composite Board 1.5 0.301 3.32
Polystyrene - Expanded (EPS)** 1.0 0.260 3.85
Polystyrene - Extruded (XEPS)*** 1.0 0.200 5.00
Sprayed Polyurethane Foam**** 1.0 0.150 6.88
Cork 1.0 0.280 3.57

* Problems have been reported with regard to the use of Phenolic Foam roof insulation. Incidents of deck corrosion have been reported in cases where the insulation is in direct contact with steel roof decks and there is moisture present.
** Molded, Expanded Polystyrene Insulation also referred to as MEPS, can have an R-value that will vary from less than 4.00 to slightly more than 4.00. The amount shown is an average amount used for roof system R-value calculations.
*** Extruded, Expanded Polystyrene Insulation is commonly used in Inverted Roof Membrane Assemblies (IRMA).
****Sprayed Polyurethane Foam (SPF) will have an R-Value of 7.14 when it is newly installed. After it ages a few months, the R-Value will reduce to somewhere around 6.88.

The C-value (C) is a measure of the Thermal Conductance of the material and is the reciprocal of R, or

C is determined only when the Thermal Conductivity (k) of a material is known.

Thermal Conductivity is the measure of the amount heat that will be transmitted through a one inch (1") thick piece of homogenous material, one square foot (1 ft.2) in size, in one (1) hour, when there is a one degree Fahrenheit (1° F) temperature change. The equation for "k" is:

Now let’s see how easy it is to figure the R-value. First of all, you need to know what the components of the roof system are. We’re going to figure the value of some common ones. Let’s assume the roof system consists of a smooth-surfaced built-up over ¾" of perlite coverboard over 2" polyisocyanates insulation on a steel deck in the winter. The season makes a difference with the value of the outside air film. Let’s start from the inside and go out.



Inside Air Film


Steel Deck


2" Polyisocyanurate (5.56 * 2)


¾" Perlite (2.78 * 0.75)


Smooth Built-Up Roof


Outside Air Film in Winter




Total R-value for the above roof system is 14.54

R-Values of Wool Insulation

In studies performed upon wool insulation in Europe the following R-values were proven to exist for carded wool batts:

mm Inches R-Value
60 2.36 R-9
80 3.15 R-13
100 3.94 R-16
120 4.73 R-18
140 5.52 R-21
160 6.3 R-24
180 7.09 R-28
200 7.88 R-31
220 8.67 R-34
240 9.46 R-37
260 10.24 R-40
280 11.03 R-43
300 11.82 R-46

Batt Insulation

Insulation batts remain the most common and easy methods of insulation in the U.S. Batts are available in fiberglass, plastic fibers, mineral wool, and natural fibers such as cotton and sheep’s wool. These are available in standard dimensions to fit standard wall studs, attics and floors, or may be hand-cut to fit different areas


Fiberglass is the most common insulation method today. This insulation may be found in medium and high density batts. Each is used for a different purpose. Denser product may be used for insulating areas with less cavity space.
Although the most common insulating product, it does require installers to take certain precautions during the installation process. Fiberglass batts are made from glass that is blown pr spun into thin fibers, and also contain formaldehyde-a gas that may cause watery eyes, and burning sensation in the eyes and throat. These factors may cause lung and skin irritation during the installation process. Some companies are now beginning to offer formaldehyde-free fiberglass batts which may help ease health concerns among installers and homeowners. Fiberglass batts provide an R-Value of approximately 2.9 to 3.8 per inch of thickness.


This insulation consists of recycled cotton and plastic fibers. One of the main benefits of this product is its softness and that it can be handled with casing itching or irritation. It also provides an R-Value similar to that of fiberglass 3.0 to 3.7 per inch of thickness. This product contains a low toxic boric acid as flame moisture and insect and rodent repellent. It is also 100% percent recyclable, has no formaldehyde off-gassing, and does not require any safety equipment.


This product is made from sheep wool, and like cotton batts, is treated against insect and rodents as well as fire and mold. This product is commonly used in other countries and quickly gaining popularity among Americans households and builders. Wool insulation is typically used to provide thermal and acoustic insulation and is capable of providing an R-Value of 3.4 to 4.2 per inch of thickness, better than cotton or fiberglass.