I have a 10'x12' wood deck structure out in front of a 30' retaining wall on top of a 100' bluff overlooking the Mississippi river. Pretty cool. But, its' in poor condition. The deck boards are in very bad shape and the whole structure sways side to side.
DO I reconstruct the entire deck (fairly expensive since you're working off 30' ladders, or replace the deck surface and add cross bracing to the steel support piers to prevent the racking stability issue. Or rebuild or reconstruct the entire deck.
The wood frame is in fair condition. its' not rotted and seems solid enough, but it's only 2X6's on 24" centers. Preferred would be 2X8's on 16" centers.
The supports on the end are three (3) 4" round steel columns. the frame is double 2x6's up on the perimeter. the front of hte deck is resting on the sloped retaining wall and has 2"x1/2" steel tie straps anchoring it to the retaining wall. the tie straps are embedded in the wall.
If cost was no object, I reconstruct the deck with welded steel frame and wood deck boards.
The 2nd solution is to repalce it with similar construction, but use tigher joist spacing.
The bases on the steel posts could use to have the footings repalces. Then rest on the base of the retaining wall, but one looks ot be undercut somewhat and I don't think any of them are anchored to the wall.
Another option could be a all new deck with a partially cantilevered design using angled braces rather than vertical posts. These could be 3 4X4's and have steel achor bolts placed in the wall. The downside is that it would place a slightly greater load on the wall.
One final solutoin would be a catilevered design where supports are anchored deep in front of the retainign wall towards the house, and the entire deck hangs out over the bluff with either no supports or angled supports only. This would however require a adequate mass of concrete in the form of a reverse tapered or stepped footer to counter the calculated loads. It would also require that the top of the retaining wall that site 16" above grade be opened wider than it is now, or be notched for the supports. But again, if this design is slightly wider tha the current deck, it could be built first, and the old deck demoed below it.
The real challenge is that you must work on a slope at the base of a 25' retaining wall using tall ladders. Actually, just to get teh the base of the wall you'll have to lower the 30' ladder over the top of the retaining wall. There's no other way ot reach the base of the wall otherwise without driving a 1/2 mile north and hiking through scrub brush.
I'll try and post a photo later.