Slate is a bit more difficult to work with and less forgiving than asphalt shingles because they break easily. However, a slate roof can create a colorful, hand-crafted look that adds to the overall appearance of a house. Cutting slate to size requires using a special pressure cutter or a pick-like hammer that splits the slate. Slate is easily damaged by walking on it, so you may want to contact a pro for repairs on areas that you can't reach from a ladder. Repair Replace a broken or missing slate shingle by working a nail ripper underneath the upper slate or cut the nailheads with a hacksaw blade.
Test fit the new shingle and mark two nail holes on it at the gap created by the upper shingles.
Remove the new shingle, and from the back , punch new nail holes. Fit and nail the shingle in place. Slide a small piece of builder's felt under the upper shingles to cover the exposed nailheads. Hand-split shakes have a rough, textured look on the front and often smooth on the back. Wood shingles are machine sawn smooth on both sides.