With the crappest job in the world under our belts, we moved on to insulating the walls.
The original plan was to insulate with light straw clay (LSC), as we did with our power shed, which by the way is featured on the cover of the hot-off-the-press Essential Light Straw Clay by Lydia Doleman.
LSC is an outstanding infill material, turning agricultural waste and clay slip into a carbon sequestering, fire resistant insulation that can last for centuries as evidenced by ancient half-timbered, straw-clay wall systems across the UK and northwestern Europe. The downside is the huge amount of work in the volumes we’d have needed and it dries at about 1” per week in summer conditions. So in the end, only being ready to insulate in Nov during the onset of wet winter gales, timing conspired against us.
So what to do?
Pulped fiction to the rescue.
We switched to dense pack blown-in cellulose insulation. ‘Cellulose’ insulation is basically recycled shredded novels, newspapers and office paper mixed with non-toxic borate as a fire, insect and mould deterrent. This stuff is hard to beat. At R 3.8 / RSI 0.67 per inch it’s more than twice as insulative as LCS or straw bale, which are also cellulose but with fewer air pockets and thus less insulative. Blown cellulose reuses a land-fill bound waste product and it sequesters carbon, which is vital to minimizing the embodied carbon and climate change contribution of our house. It’s also very fast to install and when dense packed it also slows air movement through walls while managing moisture very well.
We stapled and lightly glued agricultural floating row cover to the wall studs and then blew and blew and blew. In a couple of days we’d pump 247 bags into the walls – some 2790 kg of recycled paper. On the main floor with the 16” insulation cavity this gives us about R60 / RSI 10.57 and upstairs the 12” cavity provides about R45 / RSI 8.03. This [pun intended] blows the BC Building Code and its R24 / RSI 13.6 out of the water.
But did I mention that it was the dustiest job in the world?
Next up, we get plastered!