I'd love to use sheeps wool in a hut but I am feart of damp, vermin and rot being introduced by an organic material built into walls, roof & floor. Reading the manufacturer's blurb is all very well but they, naturally, give a best case scenario of performance.
Against these fears about wool is my unhappiness at using insulation products that are petroleum based or have high-embodied energy and may be sources of toxins. It feels like a real bind. It seems quite hard to get unbiased real-world views about insulation on the web.
Would a wall that allows moisture to escape outwards ("breathing wall") give long-lasting i.e. decades of useful life from wool? I'm thinking of a hut wall with (from the inside):-
- 4mm wood/veneered plywood paneling with Danish Oil finish
- Non-permeable vapour barrier behind panelling
- 75-100mm sheeps wool between timber studs
- OSB 3 sheathing, 9mm
- Permeable breather membrane
- 25mm vertical battens to all air circulation/ventilation
- 40mm horizontal battens to fix cladding to
- 20mm vertical "batten on board" timber cladding, open at top & bottom to allow air circulation.
Can anyone foresee any problems with using sheeps wool in such a wall?
Hi Sam, Thanks for you comments & insight. very helpful. I'll have a look at the jute and hemp.
Hi William, Using sheepswool in timber frame construction is fairly common. It's lovely to install and pretty non-toxic except for those with lanolin allergies. Couple of things that might be useful: • the Danish Oiled ply and vapour barrier will theoretically prevent any moisture passing through the wall, preventing the wall from 'breathing'; • the screws/nails used to fix the 4mm ply will create lots of puncture holes in the vapour barrier, effectively making the building breathe, but not in an intentional way! • a major risk with sheepswool is infestation, whether treated or no. The external breather membrane has to be incredibly well-sealed at all joints and edges to prevent beasties getting in. If you're at all concerned then it might be worth considering another non-animal insulation such as hemp or jute, which is very low cost, non-toxic and non-petrochemical. Sam Foster