It PVC sofit board.
Normally used like this,





But i just ussed it as full length along the walls.

It Tunged and Grooved so it easy, cant remember right, but you have to start at the bottom and work up.

Its cheap. but only good if your use ply on the inside of garage for strength.

i used it on the 2 wall faceing the front of the house, the back to walls are Galvanized sheeting.


Heres a pic half way trought.
yup bottem up. hehe