Problem: deck surrounding an above-ground pool (deck standing on wood posts into sand without appropriate foundations) has sunk badly at one corner, has sunk 9 inches at the pool edge, and
17 inches at the outermost corner. Thus the corner post has sunk about 17 inches and two or more intermediate posts about half that.(This deck & pool are about 19 years old and I contemplate repacing both whenever the pool collapses . . . I.e. repairs should last two or three years.)
I plan to raise the deck and support it by a new joist of doubled 2x6" cedar (i.e. 4x6" total) diagonally under the corner, and supported at each end by new posts (4x4" lumber) on 2ft concrete slabs atop the ground (sandy soil). The deck must first be raised by one or two auto jacks, placed atop 12" drums cut from a large poplar tree (2 ft. diameter.)
Questions remain:
- Should I raise the deck with a single jack under the deck (lifting the new diagonal joist) or a pair of jacks outside the deck footprint? This would require having the diagonal joist extend at least 3 ft. beyond the deck footprint at both ends (and cutting off the surplus when the job was finished.)
- How fast should I try to raise the deck? I.e. if it seems to stick at (say) 3 inches, should I just leave it overnight and try to raise it another
- Two new pillars (resting on concrete slabs on the ground) will be hangered to the new
- If I can raise the deck and insert new supporting posts as planned, would there be any point in digging below the old corner post, with a view to filling the empty hole below it (probably 17 inches deep)?