Can you extend concrete fence posts?

Are you looking to make your fence taller with existing concrete posts? Find out the best methods to achieve extra height.

There are lots of different concrete post extenders on the market but unfortunately most look very different to the existing posts and can look pretty ugly.  Some of the best examples are these devices found on Amazon.

Extending Concrete Fence Posts

The only real way we have extended concrete posts is in the following way. 

The fence below is using concrete posts that have been extended.  We do have a blog on 'if panels can be higher than posts' but the answer is 'not really'.

This can only be done with one solid panel that is taller than the posts, so doesn’t work if you want to add a trellis on top. We would always recommend high quality wooden fence panels that help support the top of the fence above the existing concrete posts.  

The instructions below involve new panels, using wooden ‘H’ posts to slot above the existing concrete posts and in the gap between the new panels. We have then added pieces of treated timber to clad the existing posts to make them look good. 

Step 1 - Check Existing Concrete Posts

Check that the existing concrete posts are solid and secure. They must be strong enough to support the additional weight and withstand wind pressure once the new section is added. So give them a good push.  

It is also worth checking the width of the slot at this time to make sure it is wide enough to take the fence panels you order.

Step 2 - Remove Old Fence Panels

Remove the old fence panels carefully to avoid damaging the posts.

Step 3 - Install New Fence Panels

Insert the new panels into the existing concrete posts. Be aware (as above) that not all panels will fit the existing slots, so check compatibility first. Choose strong, well-built panels to help support the extended height of the fence.  View our blog on 'How to replace fence panels in existing posts'

Step 4 - Inserting H Post Inserts

Once the new panels are in place, use a timber H post cut to size. It should run from the top of the existing concrete posts to the top of the new panel. In our example, we used Jacksons standard slotted fence posts (Jakposts), as they worked perfectly size wise compared to the existing concrete posts and we purchased at the same time as the Jacksons Featherboard panels.  

The above image shows the panels that have been inserted into the concrete posts and then a small piece of cut 'H' post that has been slotted between the panels.  Ignore the capping on the left.  

Step 5 - Screwing Together

Secure the H posts by screwing through the post into the panel. It is best to drill pilot holes first to reduce the risk of splitting the timber, especially in smaller pieces.

Step 6 - Cladding the Posts

Install the cladding. We used Jacksons standard capping rail and cut to length so that the timber was not in contact with the ground.   We used outdoor adhesive to attach the timber to both the concrete posts and the wooden H posts. This creates a neat and cohesive appearance.  

The above image shows the old concrete post and the new 'H' infill piece covered by the capping rail.

Step 7 - Capping Rails

Add the capping rails. Gently screw them into the H posts and panels, taking care not to split the rail. We used Jacksons Heavy duty capping. This allowed it to cover the posts and also the timber that is cladding the posts.  

Step 8 - Infill Pieces

Finish by filling the visual gap between the cladding and the panels. We cut the battens to size using a table saw and used outdoor adhesive again to fix the timber pieces in place. 

The finished example of an extended fence post can be seen below.  

We didn’t clad the gravel boards but thought they looked ok not cladded.