How to put up a fence with concrete posts

If you want your fencing to form a long-lasting barrier, then you need to look for the strongest possible posts. Wooden posts look great, but regardless of the treatment you give them, they will never match the strength of metal or concrete posts: concrete is a wonderful value material that guarantees decades of maintenance-free support for your fence panels.

We supply slotted concrete posts that work perfectly with large wooden fencing panels. We also sell morticed concrete posts, pre-cut with slots needed to take the arris rails that are used for feather-edge or close-boarded fencing.

Both panel and close-boarded fencing can be further enhanced with a gravel board at their base, giving extra weather proofing and strength. Remember to add the gravel board to your measurements if you’re using one.

Here’s our guide to putting up a fence using concrete posts.


Before you start

writing a list

If you’re working along a shared boundary, then it’s advised to have a word with your neighbour first. They’re bound to appreciate the notice of your plans – asking them when would be least inconvenient is a nice little touch – and they’ll be more likely to give you permission to work on their side of the dividing line, which makes for a much easier job.

Make sure your fence doesn’t need planning permission. It’s unlikely that you will, but, if it’s over 2 metres in height, you might need to speak to the council first.

As you need to dig quite deep holes for this job, you should check the ground for any underground pipes or cables.

It would be wrong to say that this is an easy job. A good DIYer shouldn’t have too many problems, but it’ll be way easier with two of you. Plan everything on paper, and remember that you need specific posts for specific jobs – end posts, corner posts, intermediate posts – with pre-slotted and pre-morticed posts.


1. Planning and measuring

Ruler and pencil

Both panel and close-boarded fences are generally set to fixed lengths, dictated by the size of the panels or the rails to which the fencing boards are fixed.

You may need to cut a board or rail to fit into a wall or corner, but always try to optimise the number of evenly-spaced posts.

Use pegged string to mark out the line of your fence. Space your posts using either the fencing panels or arris rails themselves, or use a length of timber cut to the right length – whatever you choose to use, be exact!

Fencing is designed to be laid on level ground. Generally, if you are setting up fencing on sloping ground, you should keep the fence panels or rails as horizontal as possible, as well as cutting or burying a gravel board to level the slope. Steeply sloping ground becomes even more technical and it is worth employing a professional for such jobs.


2. Digging the post holes

Digging foundations for concrete posts

Remember that of an 8-foot post, 2 feet will be buried (around a quarter underground is a good, scalable guide).

You may need to allow extra depth for some foundation under the post, though at this depth, concrete posts should sit strongly in most soil types. So, unless the ground is waterlogged (work in dry weather conditions as best you can) or very unstable, you should be fine.

Dig as vertically as you can – if you have specialist tools like clamshells or a tile spade, then by all means use them. If not, simply use a standard spade to get down to the required depth. Professional advice tends to be that the post hole should be three times the width of the post. This is being very cautious, and if you want to trim this size, you should be fine, especially if you are installing your fence in good, solid ground.


3. Securing the posts

Concrete posts are heavy, and if you haven’t got a friend to help you through the whole project, then this is the part when you should rope someone in for a couple of hours – it will pay dividends.

Post mix is the best concrete for the job: it can be dry mixed with gravel before setting it in the hole.

If the base of your post hole isn’t stable, then use stone or rubble to set a strong foundation.

Your trusted assistant will need a spirit level to ensure that the post is exactly vertical when it is set in place. You can use short wooden stakes or bricks placed horizontally to prop the post into position, before putting your postcrete and gravel mix into the hole.

Follow the instructions on the post mix bag and add water. It should dry quickly to give you a strong post setting – keep checking the vertical level as it dries.


4. Erecting the fence

Measuring with a spirit level

You can either set all your posts in one go or work along in pairs. If you’re confident in your measuring, then the first method is by far quicker, but for those of you who do not wish to risk the terrible frustration of a beautifully set fence post not fitting its panels, opt for the latter option. With post-and-rail fences, it is almost always safer to set up in pairs as you go. Use a board and spirit level to check levels of the tops of posts.

With AVS Fencing’s posts, your gravel boards can be simply slotted into place – use either concrete or timber gravel boards. If you want an extra layer of stability, a layer of wood laid across the top of a concrete board allows you to screw fence panels down.

Gravel boards are your last chance to get a proper level fence. Use a spirit level and proper measurements to ensure that their tops are level across the full length of the fence.

Fencing panels can simply be slotted in on top of any gravel boards. If you’re laying wooden fencing directly onto the ground, you should leave a small gap to, at the very least, slow down moisture-related rot.

Close board fencing is a slightly more technical proposition. First, arris rails need to be run between – you can fix the bottom rail in place with a stake midway between the two posts (this will also give extra support). The boards can then finally be nailed into place.


5. Finishing touches

Painting a fence

Most fencing panels and boards come pre-treated with preservative. If you want to add any extra treatments, for either longevity or cosmetic reasons, it’s far easier doing it before putting the panels in place.

And remember, it’s always worth checking along your fence to ensure that everything is securely in place, looking good, and will perform as it should.

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01 Jun 18