Plywood will not last long exposed to the elements. While the plywood sheathing will be protected by the siding, leaks will still occur unannounced to us which will rot out the plywood sheathing. To protect the plywood, tar paper is placed around the tiny house!
Since I'm working alone, tar paper was installed in smaller (more manageable) pieces. I started at the bottom and worked my way up to the roof. The bottom of the next row overlaps the top of the lower row to provide a shingle effect, effectively keeping the water from entering the tiny house sheathing plywood.
I wrapped the tar paper around the corner. When I wrap the sides of the house, those sheets will overlay these sheets. It is important to work on one wall at a time, covering it from bottom to roof with overlapping layers.
Battens were cut and screwed to the the outside, tacking down and supporting the tar paper. If battens were not used, the tar paper would probably rip off the nails that hold it and blow away in the wind. Battens help hold everything in place and keep the tar paper installed on the tiny house until the siding is ready to go on.
The windows are left covered at this time as the tar paper will keep out any water that might come in. After everything is wrapped, the windows will be cut out in the tar paper and the glass windows installed. Until then, the holes will be protected from rain as construction progresses.