Do you have areas of failing paint on exterior wooden structures? Does your support post feel mushy and your finger sink under the surface when pressed? You may have a problem if you are experiencing these issues.
This is a pretty common problem on exterior wooden structures and highlights the need for annual maintenance. All outside wood structures need to be looked at for failing caulking and paint every year. Caulking should be removed and renewed if found cracked and failing. Areas of failing paint should be repaired and repainted to avoid problems like these.
With the long term neglect of this structure the only real option is to replace the rotted wood and start over again. Putting paint over the top of the rotting wood will hide the damage for a bit but it doesn't change the fact that the underlying wood is structurally unsound.
Brian Jovag, owner of Jovag Home Inspection.