Beam Damage Under Deck
This wood beam located underneath the
wood deck and wood framing has suffered from years of moisture and
obviously needs to be replaced. The deck framing looks like it's in good
shape (the floor framing looks new) and someone used pressure treated
lumber for the decks floor joist.
Here's a good example of using pressure treated lumber to solve one problem but not using pressure treated lumber to solve another problem. This deck beam is one of the most important members of the framing and should have been replaced before the new deck floor joist were installed.
Anyway now it's too late and the floor joist will need to be raised, so that the beam can be replaced and then the floor joist can be safely attached to the new wood beam. If you're planning on replacing this beam, make sure that no one walks on top of the deck while you're working on it. Caution tape works good in situations like this, but don't forget to notify the homeowner and the building occupants before you get started.
This wood beam has suffered from years of moisture and replacing the damaged wood beam, will guarantee future wood rot or damage. Try to find out how the deck beam got damaged in the first place. Time for a little detective work.
Check the roof drainage first, this seems to be the biggest culprit for wood damage on the buildings and exterior. If there is water draining onto the deck, off of the roofing, near this area I would suggest that you install a gutter system to drain the water safely away from the building.
If this is not the case, check for leaking water pipes or excess of moisture underneath the deck. This wood beam is severely damaged and the problem should be easy to find.