How can you fix rotten wood that is from the outside of house through to inside where an old deck used sit and caused water damage wall plywood sitting on joists?

1. Assess the damage: Determine the extent of the damage to the wood. If the rot is contained to a small area, you may be able to repair it yourself using basic tools and materials. If the damage is extensive, it is recommended to consult with a professional.

2. Remove the damaged wood: Using a pry bar or crowbar, carefully pry up and remove the rotten wood. Be careful not to damage the surrounding healthy wood.

3. Clean the area: Remove all debris and dirt from the area where the rotten wood was located. You can use a brush or vacuum cleaner for this purpose.

4. Treat the area with a wood preservative: Apply a wood preservative to the area where the rotten wood was located. This will help to prevent any future rot from developing.

5. Install a new piece of wood: Cut a new piece of wood to fit the area where the rotten wood was located. Make sure that the new piece of wood is the same type and thickness as the original wood.

6. Secure the new piece of wood: Attach the new piece of wood to the joists using nails, screws, or construction adhesive. Make sure that the new piece of wood is securely attached.

7. Finish the area: Sand the area where the new wood was installed to make it smooth. You can then paint or stain the new wood to match the surrounding wood.

8. Inspect the area regularly: Regularly inspect the area where the rotten wood was repaired. If you notice any signs of rot, take immediate action to repair the damage.

By following these steps, you can repair rotten wood and restore the structural integrity of your home.