Can I Increase the Height of my Existing Fencing Without Changing The Posts?

It’s an age old problem that often arises when moving into a new property or sometimes when new neighbours are moving in next door to you. Often people are just looking to increase the height of existing fencing due to security concerns or are simply looking to add trellis to the top of existing panels to allow climbing plants to grow into the fence, but what can be done to increase the height of existing fencing without having to change the posts?

Well, take heart in the fact that there are a number of options available to you even if you have concrete slotted posts. For ease of understanding we will have to split the explanations according to what you are looking to achieve.


1.) Extending the Height of Traditional Panel Fencing on Concrete Posts

If you simply want to increase the height of your garden panel fencing you can go about it in one of two ways. The first of which would be to remove the existing timber panels and slot a Concrete Base Panel in between the posts before slotting the panel that you had previously removed back in on top. Concrete Base Panels are very heavy however and it is often difficult to lift them up over the top of the posts to slot them into the recesses on the posts. You may wish to use Litecrete Base Panels in this instance as these are approximately half the weight of standard Concrete Panels and will make the job considerably easier. The second method here can be achieved again by removing the existing panels but this time slotting in new panels that are taller than the ones you have removed.

When increasing the height in either of the ways outlined above you will be left with a gap in between the tops of the panels where they protrude above the posts. In order to fill this gap you will need to use timber infills that simply fit between the panels, closing the gap between the protruding panels. These can be topped with timber post caps and finials if required.


2.) Adding Trellis to the Top of Existing Fencing on Concrete Posts

This is slightly trickier to achieve than you would first imagine unless your posts have been fitted considerably higher than the tops of your panels. It is not advisable to just screw the Trellis to the tops of the existing panels without any part of it being supported in the slots of the posts as they will quickly fall over, ruining the tops of your panels as they do. The solution to this problem is achieved by buying new panels with an inbuilt Trellis that can be slotted in to replace the existing panels. This is easily achievable when using Waneylap or Overlap Fence Panels as the rear vertical supports are extended above the top of the panel and form the framing and support of the Trellis. It is also possible to achieve using Closeboard Fence Panels (when made with side frames). Please call to discuss your requirements in either of these instances.

If your existing panels are in good condition and you don’t want to replace them there is another method that will allow Trellis to be fitted above. This method would involve attaching timber battens to the rear of your posts so they finish above the post at the height that you would like your trellis to finish at. Trellis can then be screwed to the front of these battens above your existing fencing. The trellis will be slightly offset towards the rear of the post using this method which can be alleviated (if required) by fastening plant on battens to the front of the timber uprights you have previously attached to the top of your posts then fitting your Trellis between these directly above the existing panels.


3.) Extending Existing Timber Posts (Square Section).

This a fairly simple task as all that is needed is a Timber Post Extender and a short length of timber post of the same section to fit above. The Timber Post Extender is a sleeve that fits round the top of the existing Timber Post, allowing a new section of post to be fitted into the top of the extender which holds it securely in place. Once the new section of post is fitted you can screw your Trellis into the new section of post fitted in the extender.

If you are looking to increase the height of your fencing with a solid panel that will replace the existing panel when on timber posts you would again follow the steps above to increase the height of the post, but before fitting a new panel you would first have to remove the existing Timber Panel. If the panel has been fitted using Met Clips or screwed directly into the posts it is simple enough to remove with a screwdriver. When the panels have been nailed directly into the sides of the posts a handy tip is to use a Hacksaw Blade (detached from its handle) to cut through the nails into the post. Start by sliding the blade down between the top of the post and panel until you get to the point where the first nail is situated, grip the blade at each end and carefully saw through the nail. Repeat this for each and every nail securing the panels but make sure you wear a decent set of gloves to stop you from cutting your hands, standard gardening gauntlets provide ideal protection.


4.) ‘In Situ’ Fencing

Each of the above methods generally relate to panel fencing rather than ‘in situ’ fencing whereby the boards are nailed onto horizontal rails that have been secured to either concrete or timber posts. This type of fencing can be made higher by removing the existing boards and nailing longer ones on in their place. Remember though that the boards will be unsupported at the top when doing this and may be snapped if somebody tries to climb over. You may choose to fix the new boards to the rear of the existing rails, leaving the existing boards on the front in place but remember that the increased weight will be adding additional stresses to your posts so make sure these are in good condition before doing this.


Points to Consider Before Increasing Fencing Height

As mentioned above it is important to remember that increasing the height of your fencing panels will increase the wind load on your fence and as such you need to be certain the posts will be able to withstand the increased stresses. Timber Infills and Post Extenders will not improve the structural integrity of your posts and drilling battens onto concrete posts will weaken them slightly.

You must also make sure that you stick within the planning regulations for perimeter fencing. The maximum permitted height for fencing before requiring planning permission is 2 metres, or 1m where the fence is situated next to a highway used by vehicles or the footpaths bordering such highways. If your house is a listed building, is situated next to a listed building or is situated in a conservation area then the regulations may be different and a call to your local planning department would be advised before carrying out any alterations to your fencing. For further information on planning regulations please visit


We’re Here to Help

I hope this article helps in some way and will allow some of you to competently tackle the problem of increasing the height of your existing fencing. If you are not sure that you have the DIY capabilities to carry any of the above out always remember that there are professionals that will undertake work of this nature on your behalf. We install fencing around South Manchester and Cheshire and will be happy to carry out this type of work. Please call 0161 477 0010 to book an estimate or discuss your requirements. If you live outside our area then contact your local fencing company who I’m sure should be able to do the work for you.