Watch this video from This Old House to learn how to work with fiber-cement board.
1. Wrap plywood house corners with 15-pound builder's felt; secure felt with staples.
2. Hold fiber-cement board against house, flush with the corner; secure the board with galvanized nails.
3. If necessary, add another fiber-cement board to extend up to the frieze.
4. Apply silicone caulk to end joint between boards; nail board flush with corner.
5. Nail fiber-cement boards to the opposite side of the corner, keeping them flush with the previously installed boards; caulk all joints with silicone.
6. Run a bead of silicone caulk along vertical corner joint between the fiber-cement boards.
7. Nail a second layer of fiber-cement boards over the first layer.
8. Apply another caulk bead along the corner joint, then nail on a third layer of fiber-cement boards to create the desired thickness.