When I visited a collective of Tiny House builders earlier this year, they recommended that I sheathe my structure with wood fibre boards. Though they are made from pressed wood fibre, they have a different texture than OSB or MDF. They are lighter, 'fluffier' perhaps. And according to the manufacturer's website they are entirely compostable- no chemical glue. They provide extra insulation, regulate humidity, and are wind and rain-tight. They have a tongue-and-groove structure that interlocks the panels- although my surfaces are so small that I couldn't really take advantage of that!
One big question which I hadn't resolved in the design was how to make these panels go around the curved part of the structure. I ended up making saw cuts to half the depth of the panel and then bending them. It worked, although I think that compromised the wind-and-rain tightness...
To fill in the gaps, I mixed the leftover fibre with water and glue and used that as a paste. It's a bit of a hack solution, but I'm not sure what I could have done differently. The manufacturer does make flexible insulation but those are more like batts and not like sheathing board.
|Pre-curving the panel|
With a friend we put up the walls, then I continued with the ceiling by myself. It was an interesting puzzle to get the sheets on top of the roof and lined up correctly.