Cleaning and Using Sheep Wool for Insulation

Sheep are amazing creatures to have on your permaculture farm. For very little input they give us so much in return. They manage our pasture helping to keep our land fire safe, they provide us with income from meat, cheese from their milk and manure for our food forests and growing gardens.

This article was my first published article in Permaculture Magazine:


Last year we decided to start using both the wool for insulation and lambskin for sheepskin rugs helping increase our output from our sheep and decreasing waste.

We processed the wool from 35 sheep, treated it and used it in our house as insulation. We experimented different ways of cleaning it to see what works best for us. We calculated the cost-saving and advantages of homemade sheep wool against store-bought insulation to see if it is worth the work to use our wool and even if it is worth buying raw wool from other farmers.

Benefits of sheep wool insulation

Sheep’s wool is an outstanding insulator with as good or better insulation properties as roof-mate or rock wool. As opposed to shop-bought insulation the homemade wool is not processed into compact blocks. The loose wool can be pushed into small gaps and does not need to be cut to size, making it is easier to work with.

Sheep’s wool is more environmentally friendly, is not itchy to work with and is fireproof. It regulates humidity, does not burn, purifies the air and is a good sound proofer.

All in all, it is better than any insulation we have used in the past and is more cost-effective.

sheep wool insulation
Installing sheep wool in the ceiling

Is sheep’s wool cost-effective?

If you buy manufactured sheep’s wool insulation it is very expensive. We used our own sheep’s wool and had to pay a shearer €1.50 per sheep. This makes about €2 (€1 per kilo) of raw wool per sheep that we could then sell to a dealer. Our sheep do not produce a lot of wool but if you have Marino sheep, for example, you may yield double that amount. We wanted to know if the work of processing it is worth it or if it is better to sell the wool and buy insulation. We also wanted to know if it would be worth buying raw wool straight from farmers and cleaning it ourselves for insulation on future natural building projects.

We had around 60kg of raw (dirty) sheep wool which the dealer would pay €1 per kilo for. However, once we cleaned it by removing dirt, straw and lanolin, and separated some small extremely dirty parts for cleaning, this went down to about 40kg,

When insulating our ceiling, the space between the ceiling cladding and floorboards above was 10cm deep. When stuffing this compactly with our wool we were able to fill a space of 5.5m wide by 1.8m long, a total of 1 cubic meter of dense sheep wool insulation. Usually, with store-bought insulation for a ceiling, we would buy 3cm thick insulation. With our method, we were forced to use thicker insulation as the space that we were filling was 10cm deep. This means we got fewer square meters of insulation as we could not regulate the thickness. This, however, does mean we are well insulated for sound and heat due to it being thicker.

Considering the amount of insulation required for our 10cm-deep ceiling space, we would have had to buy around €158 worth of roof-mate or €253 worth of shop-bought sheep’s wool insulation. Our wool cost us far less.

We paid €35 to have the sheep sheared, and we could have paid €60 to buy the same amount of wool from local shepherds that we know. So financially the sheep wool works, but is the time and effort it takes to clean and prepare it worth it?

Methods to clean the sheep wool

Before the annual shearing of the sheep wool, we took extra care making sure the sheep’s bedding was refreshed every day so that the sheep are as clean as possible, i.e. no poo stuck to the wool!

After shearing the wool, we removed any large pieces of dirt by hand. We then tried the three most common cleaning methods to see what works best for us. When cleaning you want to remove dirt and the strongly-smelling lanolin.

Method 1: Cleaning in the wool in the river

We put the sheep wool into potato bags and hung them in our waterfall for an hour. You could also do this in a river.

This was the best method as it made the wool the cleanest. However, we could only do one bag at a time as that is what would fit in the waterfall. We would need to spend a whole day or even two doing this. The wet wool was also very heavy to carry to the drying station. If we did this method again we would set up the drying station down by the waterfall.

Method 2: Rinsing the wool in a sieve

We placed a small amount of wool at a time in a sieve and ran water through it until it was clear, then soaked the wool for a few hours and rinsed one more time.

This was time-consuming but the results were good.

Method 3: Soaking the wool in a large container 

We put a lot of wool into a large container and filled the container with water and let it soak for 24 hours, drained the water and repeated this for one week until the water ran clear.

This was the least effort and gave a good result. We will use this method next year in an ICB (1000 litre recycled water tank). We can then use the ICB to water the food forests.

Method 4. Clean in a washing machine

We did not try this, as we wanted to avoid causing damage to the machine.

soaking sheep wool for insulation
We soaked about half the wool in a wine vat. We made a filter with a crate so we could drain the water without the plug getting full of wool.

Next year we will use an ICB to soak all of the wool at once and change the water daily. We will link the tap to the garden so we do not waste any water.

After all of these methods, we laid the wool out in the sun to dry on pallets and old bed frames so that air would circulate under it. When we dried them on old sheets they did not dry too well.

processing sheep wool for insulation
Here we first tried drying the sheep wool on sheets but they would not dry underneath so we moved them onto some pallets to create airflow underneath.

Treating the wool

We treated the wool by spraying a borax solution on one side of the wool, letting it dry and then turning it over and spraying the other side.

Having since read more comments on a Natural Building Facebook group, it sounds like a lot of people have problems with moths. Next year we will repeat the borax treatment many times to make sure it gets into all of the fibres. We will also place some dried lavender flower in with the sheep wool insulation as this also helps to repel moths.

Installing the sheep wool

This is the satisfying part. It can be stuffed in gently by hand so it goes further but we stuffed it with with a stick to make it as dense as possible for better insulation value. The wool from 35 sheep of a mixed Assaf and Lucerine breed that produces about 2kg of wool per sheep (which is a very low amount) made 10 metres square of insulation that was 10cm thick (1 cubic meter).

Installing sheep wool insulation
Stuffing the sheep’s wool into the space between the cladding and floorboards with a stick.


Our 35 sheep that produce a small amount of wool cost €35 to shear, 3 days of our labour to clean and gave us 10 square meters of wool insulation that would otherwise cost €253 to buy. It was a lot of work but we will continue to use our sheep wool for insulation in the future. We have since bought 10 Black Merino sheep that will give us more wool next year.



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