How to bolt a fence bracket to a concrete sleeper?

[Naidoo021]

Any tips on what bolt to use and how to drill a bolt into a concrete sleeper in order to attach a fence bracket to a C post? We have had no option but to concrete  a C post against the middle of an existing concrete sleeper wall that borders mine and my neighbours boundary. 

[JacobZ]

Hi @Naidoo021,

How thick are the concrete sleepers that you are bolting to?

Typically, you would use a galvanised Ankascrew, but you would need to make sure it is not long enough to punch through the back of the sleeper.

Each diameter of Ankascrew will require a different-sized pilot hole that is drilled using a masonry bit.

The shortest Ankascrew I would recommend using is 50mm long, so if your sleepers are not say 75mm thick or above, you wouldn't be able to use an Ankascrew, and you would have to drill a hole through the sleeper and use a galvanised bolt and nut with a square washer to spread the load on the back of the sleeper.

If you can advise the thickness of the sleeper, I'd be happy to suggest specific fixings and the required masonry bit for them.

Let me know what you think and if you have further questions, please don't hesitate to ask.

Jacob

[Naidoo021]

Hey Jacob the sleepers are 75mm wide and 200mm high 

[Naidoo021]

Would drilling through the sleeper and using a galvanised bolt and nut be a more secure option? 

[MitchellMc]

Hi @Naidoo021,

Since your sleepers are 75mm thick, you’re right on the limit for using an Ankascrew. A galvanised 50mm Ankascrew would work, but you’d need to be very precise with drilling so you don’t risk punching through the back of the sleeper.

Drilling right through the sleeper and using a galvanised bolt with a nut and large square washer on the back is definitely the more secure and foolproof option. The washer helps spread the load so the nut doesn’t pull into the concrete.

If you go that way, make sure you use a masonry bit to drill the hole cleanly and size it just a fraction larger than your bolt diameter. That way the bolt will slip through snugly, and once tightened with the washer it’ll hold your bracket firmly without damaging the sleeper.

Are you able to access the other side of the wall to get to the washer and nut, and have you discussed this with your neighbour?

Please let me know if you have any questions.

Mitchell

[Naidoo021]

 I’ve attached a better image. The holes sit in between the reo bars in the sleepers so I think I’m safe with drilling. I can access the other side but I’d either have to dig down 1m or lift 5 sleepers off to access the rear of the affected sleeper I need to drill. If I use the ankascrew do I need to drill the same diameter as the screw or slightly larger? I assume the galintel sleeper posts have 12mm holes? 

[MitchellMc]

An anchor screw of 12mm diameter might be 75mm long, @Naidoo021, and although it won't push through the back of the sleeper due to the thickness of the post, the hole may punch through or break out. If that side is covered with soil, it shouldn’t be a problem visually, but it’s still something to be aware of.

The key is to measure the hole in your post carefully to choose the correct size anchor screw. For a 12mm Ankascrew, you would drill a pilot hole in the sleeper of 12mm, then insert and tighten. The threads then cut into the concrete.

Mitchell

[Naidoo021]

Hi Mitchell,

To be safe, I’m thinking about using a chemset thread. The metal hole is 12mm so my assumption is to drill a 12mm hole into the sleeper, clean it out thoroughly and then chemset and twist in a 12mm threaded rod? Would this be the correct method to do this? 

[MitchellMc]

Yes, that approach would be correct @Naidoo021. Make sure to follow the instructions on the chemset product for curing time before applying any load. This method will give you a strong and secure fixing for your fence bracket.

Mitchell

[Naidoo021]

Hi Mitchell,

Ive made a rookie error by cutting the threaded rod slightly too short, I’ve already epoxy’d the rod into the hole but now can’t attach the nut onto the thread. Any suggestions? I’m thinking to just permanently epoxy the timber fence bracket onto the concrete sleeper post?