Sheepwool Insulation

Just over a year ago we installed Sheepwool insulation in our loft.
We wanted a natural insulation, with low embodied carbon that didn’t off gas.
After a rip out of old plaster boards, we recovered that all important loft ventilation, that had been blocked up and the cause of damp. After the clear up and cleanout we installed sheep wool insulation into our cold loft space.
We went with a product aptly named - Sheepwool with Ionic Protect
When we purchased the wool we did all generic checks and research online - fire safety, pest resistance, R and U values, thickness of insulation, environmental attributes, sustainability, embodied carbon and installation specification etc etc .

Easy and pleasant to install - it required no masks or gloves. Once installed it markedly changed the climate feel in the loft - from damp and musty to fresh and airy.
Very much impressed, we couldn’t understand why sheep’s wool isn’t used more widely and so wanted to open a conversation about it.
So here we are sharing our sheepwool insulation experience so far…

After installing the wool in the summer , we were in the loft regularly to check on things and to install some loft storage boards.
All was well, until December when we went up to loft to retrieve our Christmas decorations -condensation was pouring down the roofliner. Horrified, help quickly came from our Carbon Coop community members.
It was explained that hot air from the house below was escaping up into the cold winter air in the loft above and this was causing the condensation on the cold surface of our old plastic roofliner!!
Turns out we hadn’t sufficiently insulated the loft hatch or a stud wall, which was open into the loft space above - the stud wall housed the hot water pipes from the bathroom and was the source of a lot of the hot air . Armed with this knowledge, we quickly remedied the problem - stuffing the gaps and filling the cracks with insulation .
Addtionally, we were advised to install a windshear layer to go on top of the insulation, after the wool had aired out in the summer. Incidentally , the wool didn’t get too wet and we felt assured in it’s unique hydroscopic 'breathable 'qualities, which allow it to absorb up to 33% of its weight in water without compromising the insulation.

Roll on the summer again and our desire to really get stuck into our retrofit!
We were advised to top up the wool from 20cm to 30cm, so we invested in some more. As well as this we thought it wise to follow up on a ventilation check and spec for the loft - especially because of the prior damp and condensation issues. We will be having the ventilation survey next week.
Meanwhile, we further researched information about sheeps wool insulation and learned some people in the past have experienced infestations and mould growth.
We already know that mould can grow on lots of insulations if the conditions allow it - indeed our loft seems like a candidate for those conditions , hence the wise decision to have a ventilation check.

As well as this, we learned about modern methods, treatments and standards being developed to prevent moth infestations in the wool .
We discovered the current situation is some wools treated to prevent infestations use a product called Isolena or Ionic Protect - this seems to have become the recognised EU industry standard since 2016 - and it has replaced the former treatment called Thorlan IW.

Being relatively new, there isn’t much out there which looks at the success of treated installations with wool that has the Ionic Protect. I’m the only person I know so far, who has this type of wool insulation.

Moreover, sheepwool is a fantastic insulation product with some very unique advantages, but not enough press to support it - so I’m hoping our little forum focus here might attract more people with sheepwool installations to join in the conversation.

For further information, I attached some information links I discovered that discuss sheepwool insulation.

An overview of sheepwool by the Greenage

Blogspot about Ionic Protect

Youtube video in German with English Subtitles about Ionic Protect

Talks about problems with sheepwool and success of ionic protect turning the tide against moth infestation.

Insulation comparison table sourced online

A German paper - which approves Isolena over Thorlan IW as new EU standard in prevention of insect infestation in sheep wool

The Google short version intro in English for the German paper mentioned above… · PDF file

  1. Mitin FF/ Thorlan IW (no longer approved in Europe as moth protection) 8. Ionic Protect (current EGGBI recommendation since 2016) 3.1 Pyrethroids In order to ensure a permanent “structural damage-free” function of the insulation material sheep’s wool, it must be equipped with an active ingredient against moth infestation.