What's going down for the finished flooring?
If those old planks are in bad shape (cracks or broken areas between the joist, gaps and knots do not count) If it was my job I'd take the time to remove them. You can use a Toe Kick saw to cut them up right next to the walls and an ossilating or sawsall to cut out the corners.
If there not cracked then I'd add screws to every place there sitting on the joist to stablize them and go over the whole floor with Advantec 3/4" T & G subflooring. It gets attached every 4" on the edges and just follow the nailing pattern printed on the sheets for the rest. All of the long seams need to be sitting on a joist.
What's next would depend on what the finished flooring will be.
If those old planks are in bad shape (cracks or broken areas between the joist, gaps and knots do not count) If it was my job I'd take the time to remove them. You can use a Toe Kick saw to cut them up right next to the walls and an ossilating or sawsall to cut out the corners.
If there not cracked then I'd add screws to every place there sitting on the joist to stablize them and go over the whole floor with Advantec 3/4" T & G subflooring. It gets attached every 4" on the edges and just follow the nailing pattern printed on the sheets for the rest. All of the long seams need to be sitting on a joist.
What's next would depend on what the finished flooring will be.