How to extend your timber or concrete posts
Good news! Starting from scratch may not be necessary. You have the option to increase the height of your fences by adding additional panels or lattices. However, keep in mind that you will also need to extend the height of the posts that support them.
Don't know if you should Extend a Wooden Fence Post or Replace It?
Simple Ways to Increase Wooden Fence Post Height
Use Metal Post Extenders
Use wood to extend