Sheep Wool Insulation

woolThe Environtmental & Aesthetic Advantages Of Using Wool Insulation

As an insulator, sheep’s wool has inherent structural advantages over synthetic materials. The spring-like properties of wool fiber give elasticity and resilience. Tightly packed wool will naturally expand inside the wall over time rather than shrink and sink.

Wool has a high moisture threshold and moisture-retention rate, which provides excellent natural resistance to flame, combustion and/or ignition.

Wool’s hydroscopic properties allow it to both absorb and release water vapor, modulating extremes in humidity. Wool can absorb up to 40% of its own weight without feeling damp. As it absorbs moisture, wool gets warmer and avoids the risk of condensation. If exposed to moisture, fiberglass insulation begins to fail to insulate properly.


Wool is anti-bacterial as well as non-allergenic and non-toxic, and it has been used for bedding, clothing and all types of insulation and floor coverings for thousands of years.

Wool absorbs sound and dampens echo.

Wool absorbs common pollutants, i.e. formaldehyde, sulfur dioxide etc., and prevents their re-introduction into the environment.

A lot of wool is not used by the sheep farming industry. The wool of meat sheep is usually discarded. Ecologic Construction purchases some to this material that would otherwise be destroyed. We also maintain a small flock, who also work as lawn mowers and manure producers.

woolinwallsLoose-fill fiber compared to bats

Fiber insulation comes in basically two forms: batts and loose-filled. Our product is loose-filled.

Loosed filled has a higher R value and is less expensive to produce than batt insulation. Loose-fill is one-size-fits every application. When wool is washed and cleaned it is already in perfect loose-fill condition and no further processing is needed.

Most loose-fill insulation is blown-in because most loose-fill insulation is dusty, messy or the material is an irritant to workers. Loose-fill wool can be hand-packed into a wall cavity. Hand-packing may take about as much time as blowing in insulation when you consider the time it takes to rent and set up the machine, which takes two people to operate. Although the cost per pound of sheep wool insulation is higher compared to other loose-fill insulations, like cellulose and rockwool, sheep wool is a far superior, minimally processed product that has  no embodied energy since fleece is a natural by-product.

Preparing wool

Shearing is done on clean rubber stall mats and the fleeces are hung over the fence to dry out for a few hours, then they are stored in clear plastic bags until washing time.

The fleeces are washed in a mild citrus or lavender soap twice, then rinsed twice, then they are dipped in a borax solution for a final rinse. Borax (the old fashion laundry additive) is used to give additional fire resistance and pest control. The fleeces are laid on screens to dry in the sun. Next the fleece is “picked,” that is pulled apart, using a “Lil Dynamo” hand-operated machine.

There are suppliers who offer sheep wool insulation products, but these typically have poly materials blended in.

WoolRoll with Poly       Denim                      Eco-logic loose fill wool

R19                                       R19                         R19-R25, can be custom packed to desired R value
5.25″ thick                          5.5″ thick               comparable
24″ wide                             24.25″ wide           comparable
12′ long                              12′ long                   comparable
$62.30                                $160.00                    $130-170 depending on desired R value


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