The slab counts as a full block. It will float above the slab if it's on the bottom half of the space it occupies. If the slab is on the upper half of the block and is water logged however, it shouldn't float at all.
The slab counts as a full block. It will float above the slab if it's on the bottom half of the space it occupies. If the slab is on the upper half of the block and is water logged however, it shouldn't float at all.