Re: How best to replace old skip sheathed wood shakes with asphalt shingles?
The standard method that I have always seen and used is the shake and felt get pulled off, all nails and staples get beaten flat and then 1/2" plywood is applied over the top of the skip sheathing. Where the edge of the plywood falls into a gap, lay in a piece of 1x4 to support the edges OR use plywood clips.
OSB isn't good for anything, don't use it, use plywood, you'll have a much better finished product that will stay looking good throughout it's life. OSB has a tendency to warp, making your once flat and pristine roof all wavy, which can tear the felt under the shingles and cause leaks. It will also disintegrate if it ever becomes wet.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!