Decks, Patios, Porches and Docks - cantilevered balconies - water penetration?

We recently purchased a home with several cantilevered balconies. The floor beams (~6x12) extend from the interior of the house to the end of the balconies, and we have concerns about water penetration at these points. There is already extensive water damage where one of these beams enters the house, but the other ones look ok (at least to my untrained eye).

We were advised by one contractor to have all of the other beams inspected for evidence of rot. There is also a concern that some of these beams may not be pressure treated or flashed correctly. If it's true that some of this wood isn't pressure treated, can anything be done at this point? The balconies are fairly high above the ground (~3 stories, steeply sloped terrain), so it would be pretty difficult and expensive to work on any of them. What would be the best way to proceed? Thanks for any suggestions!

Now you are beginning to understand why I HATE cantileverd decks and won't build them!!

Those cantilevered joists are extensions of your floor joists. Once they begin to rot, you have to tear up the interior flooring to replace them. The cost of your deck repair just went up about 4 or 5 times!!!

Yep, we're definitely starting to understand that :(

So do you think that it would make sense to shell out some $$$ now to poke around and re-flash/caulk all of the existing joists where they penetrate the house... even the joists that have no signs of rot? Only one is currently showing signs of rot, but I suppose that this could just be a harbinger of things to come.

This would definitely be way more cost-effective than dealing with a rotted joist, but it's hard to tell if/when these joists may go bad, and how conservative we should be. Are there any early warning signs that we should pay attention to?

The first place these joists are going to rot is on the tops of them, where water and debris get trapped between the joist and the bottom of the decking. The only good way to determine just how extensive the problem is will be to remove the decking and look at the tops of the joists.

A good, and properly installed flashing along the wall where the joists enter the wall is a must. In addition to that, I would suggest (assuming that the joist are still good) covering the tops of the joists with a product like Vycor or something that the water can't penetrate before reinstalling the decking.

I wouldn't be conservative in dealing with it, I would be AGGRESIVE! The cost of replacing even one of those joists on the interior side of the wall would be huge! (New floor above it, new ceiling below it, ...)