The best way to repair the rotten deck post is to replace it. If the pole sank into the ground and was backfilled, you will have to dig the entire pole, remove it and install concrete in a sonotube above ground level. You can then mount a new deck post and post support on top of the new concrete support. The deck surface includes railings, handrails and deck boards.
If the surface of the wooden platform is exposed to sunlight and moisture for a long time, it can rot and damage, causing water to penetrate the wood and cause even more destruction. Since the surface of your deck is the most exposed to different weather elements, it is the most vulnerable part of your deck and can therefore degrade very quickly. Reinforce the post connections with carriage bolts Drill holes, thread the screws, and then tighten a washer and nut on the other side. If you notice any signs of wear and tear, you should make a decision to repair or replace your deck.
When you are sure that the platform is level and the pole is plumb, secure the pole on the platform and completely remove the jack (s). However, what do you do when your deck starts to wobble and tilt to the side? If you hear ominous creaks from one side of the deck, it may be time to replace the deck post. Deck railings offer fall protection, which becomes more essential the higher the platform is above the ground.