I’ve read way more about insulation that I thought I ever would, or ever wanted. It’s not something I’ve ever had an interest in before, but when you’re spending money on it and you want the most environmentally friendly and healthiest option out there, you’ve gotta spend some time on it.
At the time of writing this, I am still not 100% decided on all aspects of insulating our tiny home. I do know however, that I am 100% set on using Natural Sheep Wool for the walls.
This is clearly the healthiest option and by far the best for the planet.
Despite spending countless hours reading and researching Sheep Wool insulation, there are many unanswered questions, including if a vapour barrier is necessary or not. Even Margaret from Oregon Shepherd states that the jury is still out on that one!
Wool’s ability to absorb and discharge moisture without being ‘wet’ to the touch, is both a blessing and curse. Wool next to wood, is amazing, as it pulls moisture from the wood, but it also needs somewhere to allow that moisture to go to. If there’s a vapour barrier installed, this could stop the wool from discharging the moisture, meaning that moisture might end up trapped in your walls?
It’s an absolute minefield of information and tricky decisions. As I write this, I still do not have a definitive answer.
How will I insulate?
I am considering using rigid foam (EPS Durafoam) in the trailer flooring, which should hopefully negate any moisture issues I might have with wool and also fill the gaps right up to the metal so that it is a little more air-tight.
Walls & Ceiling
I then propose to use wool in the 2×4 walls and in the 2×6 ceiling. I will be making my own 2″ baffles in the ceiling (to be confirmed) to create airflow between the roof and the wool.
Wanting to minimise the petroleum products in our build, I will simply nail some 2×1’s in the corner of the rafters and roof sheathing and then attach some 3/8″ ply to that, to create the airspace before stuffing in the wool. Doing it this way means I don’t have to buy the plastic pre-made baffles. This process will add more weight, so I will make sure it’s not going to be too heavy.
Many tiny house builders have used Oregon Shepherd as their choice for sheep wool insulation. Instead of spending a potential $700 – $1000 CDN on shipping, we thought we’d get more for our money by driving down to Portland and make a mini vacation out of it.
Once we’ve decided on the final insulating methods, we’ll place our order for collection and write more about it once we pick it up.
To save you a lot of digging around the internet here’s some useful resources I found about wool. Some contradictory, but nevertheless:
These folks say: “Sheep Wool Insulation absorbs moisture from the atmosphere during damp seasons and releases it during the dry seasons. For this reason, a vapour barrier is not required and the material can be placed between the joists, directly on top of the ceiling below.”
Green Building Advisor talks about Vapour & Air Barriers.
An in-depth look at Sheep Wool for Insulation – this article confirmed my choice for using sheep wool as my main insulator.
Moisture in a tiny house Subfloor – Advice.