How to repair a broken wooden fence posts

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If there is one garden issue which always seems to raise its ugly head it is broken fence posts.

During times of excessive wet and high winds weak posts can easily break threatening to fell sections of the fence boundary. If not treated, the weight of the now flimsy fence can trigger more posts and panels to break.

​Hence it is quite important these broken posts are fixed sooner rather than later. In this article we will show you how to repair broken wooden fence posts with concrete repair spurs step by step with pictures.
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Why do wooden fence posts break?

​Timber fence posts are usually treated to defend against rot however such treatment does not last forever.

Timber is still an organic, building material and is still vulnerable to degradation over time. Typically timber fence posts snap at the base where the soil meats the concrete.

This is due to a high concentration of moisture and microorganisms in the ground slowly decaying the timber. The forces of leverage put on posts during times of heavy wind also make the base a natural weak point. 
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How to stop fence posts rotting?

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​There are various methods you can try which will stop your fence posts from rotting. 

Damp proof membrane

One of these includes wrapping the bottom 600mm of the post in damp proof membrane tightly before concreting in. However you must ensure the plastic has a tight seal with tape or moisture will still sit against the post. Continuous exposure to sunlight will lead to any membrane above the surface fracturing leading to moisture getting in. 
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Bituminous paint

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​The bottom 600mm of fence posts can be painted with a waterproof bituminous paint. This will waterproof the section concreted into the post hole. However to be effective the paint must come above the soil surface. This can be unsightly especially with lighter coloured fences. 
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 Raised dome concrete foundations. 

Typically when concreting in posts the concrete ends up about an inch below the soil level. This creates a well that collects water during times of heavy rainfall.

To counter this concrete and mortar can be neatly pointed up in a dome towards the post. This pointing can be slightly raised above the soil surface allowing moisture to run away. This means the base of the post is never sitting in damp conditions. 
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 How to repair a broken fence posts step by step

If your timber fence posts have broken you have two options; break out the old post and foundation and replace the post or install a concrete repair spur. A concrete repair spur is the easiest and cheaper option available. Below we describe in detail how to repair a broken fence post with a concrete repair spur. 
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Materials you will need:
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• Concrete repair spur (1 per post 3inch or 4 inch depending on your post thickness)
• ​Coach screws (min two per post)
• Washers  (min two per post)
• Postcrete or concrete mix (30kg per hole)
  
  

Tools you will need:
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• Spade
• Post diggers
• Graft
• Electric breaker
• Spirit level
• Buckets
• Wheelbarrow
• Claw hammer
• Adjustable spanner 

Step 1

Excavate around the post foundation to expose it and assess its condition. Sometimes these are made from weaker and dry concrete mixes which are easier to break. You are going to have to split the concrete down to the base of the hole. This will enable you to place the repair spur flush against the post without altering its position. Retain the first few inches of topsoil to dress the top of the post hole when complete.  
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Step 2

​Break the concrete as close to the post as possible, you are trying to break the concrete foundation cleanly in half! This will provide you an uninstructed new post hole to set in the repair spur and new concrete. If the concrete is particularly hard you may need to use a hammer and bolster or hand held breaker. 
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Step 3

​Excavate and break the concrete foundation down to the base of the original hole. This can be fiddly and will require continuous breaking, digging and collecting the loose which falls into the whole. Use a combination of breakers, grafts, spades and post diggers to complete this task. 
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Step 4

​Cart away any subsoil or broken concrete away to be disposed of. Some broken concrete can be used to add back to the concrete mix when concreting if not too large. Make sure the whole has consistent dimensions with no loose material at the bottom. You are aiming for a depth of between 450mm – 650mm deep. 
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Step 5

Place the concrete repair spur into the hole and make sure it can sit flush against the post and still be plumb. Plumb is when the spirit level is placed vertically against the post and the bubble fits neatly between the two lines. You may need to dig more if this cannot be done without a suitable void around the repair spur. You want a reasonable amount of concrete to encase the repair spur all the way round. 
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Step 6

​When you are happy with your repair spurs position hold it firmly in position against the post. Get at least two coach screws with washers ready to tap through the repair spur holes. Using a hammer tap the coach screws into the timber post so they bite into the surface.
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Step 7

Using an adjustable spanner, start to screw the coach screws clockwise into the timber until the post and repair spur are flush. Repeat with the other coach screw and washers until the post and spur becomes one, solid unit. 
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Step 8

​Position the post with your hands so the post is plumb or as plumb as possible with the spirit level. If you need to, wedge the post into position with a long tool like a graft to hold it as vertical as possible. When the post is as level as possible you are ready to start concreting. 
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Step 9

​Empty a bucket of water into the hole until the hole is half full with water. Empty the bag of postcrete into the hole ensuring it pours equally all the way around the repair spur. Using a rigid stick mix the water with the dry concrete mix spreading it equally around the hole. Postcrete starts to set very fast so with a spirit level check the plumb level on each side of the post. Adjust the level and keep checking as it sets for the first 5 minutes. 
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Step 10

​When set, spread the retained topsoil back over the new foundation, you should aim to have at least an inch of good soil over the concrete. Alleviate any ground compaction from the work and tidy up the soil around the post. The job is now complete! If you wish you can stain the repair spur to the same colour as the post to make it less noticeable. 
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Thank you for reading our article on how to repair broken fence posts with concrete repair spurs!

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