How to Build a Post and Rail Fence – TimberClick Projects

How to Build a Post and Rail Fence & rail.jpg Post and rail fencing is ideal for using as a boundary fence, around driveways and gardens as it looks attractive, can be tailored to suit your gardens needs and is relatively easy to erect. The most popular ones are three or four railed but you can also make two or five rail ones. It is important to remember that as with any fence, the wood will be coming into contact with soil and is therefore prone to decay. Ideally you should use fence posts that are decay resistant such as a hardwood or pressure treated timber.

Fences are usually built for decorative purposes and property separation but they can also be used to keep some forms of livestock secured. If you are going to build your post and rail fence to enclose livestock you might need to place your rails closer together to prevent them escaping as horses will require a higher fence that prevents them from jumping over it. Sheep will need a fence with rails close together to stop them squeezing through the gaps.

Tools required
  • Post rammer
  • Spade
  • Claw hammer
  • Post level
  • Saw
  • Post driver
  • Tape measure
  • Spade
  • Pencil
  • Maul
  • String line
  • Marker pegs

Materials list
  • Fence posts
  • Corner posts
  • Rail timber
  • Weak concrete mix (cement and ballast or ready mixed)
  • Additional preservative to treat cut timber ends

Step by step guide
  • Carefully measure out where you want the fence to go and decide where the ends will be, where the corner posts will be placed and mark this area out with the pegs. If an existing fence or posts are still in place, please consult our guide on fences post removal.
  • Install the first and last fence posts to establish the line of the fence and these posts can then be used as sighting posts. However, if you are building a particularly long fence you might want to break it down into smaller sections.
  • Dig a hole for the first vertical post making sure that it is as small as possible to allow you to refill the hole around the post or alternatively ram the post into the ground to a depth of a quarter to a third of the posts length. Place your fence post in the hole taking care to ensure that enough of the post is above ground to suit the style and size of your fence. If your fence is going to have morticed posts you need to ensure that the mortice holes are facing along the fence line.
  • However, if the fence is going to have nailed on rails, the narrowest side of the post will need to face along the line of the fence. Replace the excavated soil back into the hole a bit at a time ensuring that it is rammed in well ensuring that the post is completely level. You may need to use a weak concrete mix or a fence post mix if the ground is particularly soft to stop the post from moving. Carry out the same process as above to install the last fence post. If you are going to mortice the rails in your fence posts, this should not be made completely firm until you have fitted the rails to allow some movement during the installation of the rail timber.
  • Tie a string line to the first and the last fence post and then ensure that it is pulled taut. The string line should be around 750mm above the ground. Once the line is correctly positioned, it can be used to mark out the post centers along the intended line of fence (the distance will be determined by the style of fence that you are going to install). Make a small hole in the ground with the spade to mark your post centers. It is advisable to only dig out a few holes at a time to reduce any possible errors along the fence posts.
  • When digging out the holes to the correct size and depth move the string line out of the way and then replace it afterwards. Once you have placed the second post in the dug out hole sight across to the first post and the last post to ensure that your new post is at the correct height. If you are going to use mortices, the rails will need to be loosely fitted into the mortice hole until the fence post is positioned correctly. Check that the posts are plumb (vertical) using a level and are at the correct height; they can then be backfilled and rammed with earth or concrete.
  • If you have decided not to mortice the fence poles, you should now attach the rails to the first and second post using fence rail brackets. To ensure the fence is strong, the joints staggered should be where the rails or screws are attached to the posts. The rails need to be attached to the posts using 50mm galvanized nails or exterior wood screws. It is recommended that you use two nails at each end of the rail and one in the middle to ensure that it is securely fitted. Drive the nails into the wood at an angle to each other so that they are dovetailed, however the fence rail brackets may dictate a different screw / drill pattern.
  • Carry on the above procedure until your fence has been completed and then you will need to treat all of the ends with additional preservative.

    Once you have completed your fence you will need to check it regularly to ensure that it hasn’t been damaged at all as it is better to repair the fence quickly before it becomes a major issue. Any broken rails need to be replaced and loose posts rammed back in as soon as you notice any problems.

    Top Tips
  • If the holes for your fence posts haven’t been dug deep enough, you might be able to just knock the posts in using your sledgehammer or maul rather than removing and digging further.
  • To raise your fence posts, you will need to place some of the excavated soil back into the hole and ram this into the hole tightly using either the post itself or a rammer. Hardcore such as broken bricks or slabs can also be used under posts to raise them up slightly.

    Fixing an Existing Fence
    If your fence has a few posts that are wobbly, you can drive wooden wedges into the ground around the base of the fence posts. In the majority of cases, a wobbly post is a sign that the post has started to or is rotting beneath the surface. It is possible to avoid replacing the rotting/rotted post by sinking a new shorter post next to the existing one and then bolting them together.

    If you think that a project of this scale may be become your level of skill or confidence, TimberClick are able to recommend good quality tradesmen to carry out any work that you might be unable to do yourself. Please just ask and we will put you in touch with them.