Plywood Floor Repair
Here's a good example of a floor repair using plywood and
diagonal sheathing. You can use 1 x 6 to repair your damaged diagonal
sheathed floor but I would recommend using plywood unless you are going
to use 1 x 6 to repair the existing floor damage and then sheet over the
entire floor area with plywood.
One of the biggest problems with floor repairs like this, is that the floor diaphragm can be broken. This can easily be solved by installing blocks in between the old 1 x 6 sheeting and the new plywood. In the picture above, there is a good example of this.
If these blocks were not installed, the floor would be weakened. A good example of this would be taking a pair of scissors and cutting a piece of paper. You don't need to cut the piece of paper all the way through, simply cut about 3 inches into the paper.
The minute that you pull hard enough on this piece of paper, in different directions it can rip easier than a solid piece of paper. Now if I glued a piece of paper on the back of this cut, to reinforce it and let it dry, it would be a little more difficult to rip apart, once it was repaired.
This should give you an idea of how important these blocks are to the floor structural system. Make sure that you nail the plywood in the 1 x 6 to the block.