Sinking steel gate posts into the ground - too short

n.d.os

I have two steel gate posts that I would like to use at the entrance to my house. They are original to the house and were found at the back of the garden.

The posts are 160cm high. I need at least 130cm above ground which doesn't leave much to play with when sinking the posts into concrete. I plan on adding steel gates in the future (nothing too heavy) so I would like to sink the posts at least 3 feet into the ground. Advice, please.

Option one is to sink two meters of ducting into the ground with concrete, reinforce it with four rebars and fill the ducting with concrete. I would then put the gate posts snug over the ducting and fill the rest of the 30cm hole with concrete. Is this too risky or is there a better way of doing this?

Option two is to extend the length of the steel posts but I'd rather not get into this if there was some way to preserve the original posts.

Thoughts, please?

The Continental Op

I think we need picture? Are these cast iron posts or steel.

Another option is to do what you can (set in concrete will probably do the job anyway) and then tie the gate posts to solid brick or stonework pier to the side of them.

n.d.os

Here is a photo of the posts. Hopefully, this helps. There will be estate fencing attached at either side so no concrete pier, unfortunately.

elperello

Why not just weld on as much as you need ?

The extra won't be seen and if you ever want to put them back as they are cut off the extra bits.

HotWaterCylinder

You'd want to burry 1/3 of the post.

I'd burry some steel pipe that matches the internal diameter and weld them in to add length.

Watch out for the welded seam on the original posts. might foul it

n.d.os

https://www.boards.ie/discussion/comment/120626585#Comment_120626585

I think this is the most sensible option for sure. Any thoughts on using ducting filled with concrete and rebars if I can't find a pipe to match the internal diameter?

n.d.os

https://www.boards.ie/discussion/comment/120626661#Comment_120626661

Okay. I think I will see if I can get some steel pipe.

n.d.os

https://www.boards.ie/discussion/comment/120626673#Comment_120626673

You reckon? Even with gates?

elperello

https://www.boards.ie/discussion/comment/120626688#Comment_120626688

Don't decide that without consulting the gate maker.

The Continental Op

OP you might want to consider getting those posts galvanized?

https://galco.ie/rust-protection-methods/

techman1

https://www.boards.ie/discussion/comment/120626673#Comment_120626673

Definitely wrong there that's only a foot in the ground, would need at least double that, 60 cm to be stable

n.d.os

https://www.boards.ie/discussion/comment/120626912#Comment_120626912

I've heard mixed reviews about painting over galvanized steel so I'm open to opinions on this. I might put a zinc primer on them.

The Continental Op

https://www.boards.ie/discussion/comment/120626948#Comment_120626948

Some say its best to acid etch the galvanised before painting but I find oil based paints stay on new galvanized if you start off with a 50/50 Owtrol/Paint mix.

https://www.owatrol.ie/product/owatrol-oil/

It gives excellent adhesion including on galvanised steel,...

Lumen

There are loads of engineering applications where steel posts are bolted to concrete, with none of the steel going into the ground. The issue isn't how much steel is in the ground, it's how stable the concrete foundation is.

n.d.os

https://www.boards.ie/discussion/comment/120628802#Comment_120628802

That's good advice. Would adding some rebar through the concrete into the ground make it more stable?

monseiur

When I read your post I thought you had some fancy antique cast iron gate posts. What you have is two short lengths of steel pipe. My advise is don't use them, instead build two stone or brick pillars that will last and look the part. The steel pipes will rust & rot and painting them is pointless. But if you decide to use them as pillars you will need to weld on top brackets to hold the gate, so it's best to get the gates made first and weld on bracket to suit. The height of the gate will decide how deep the pipes can go - as the are short you will have to weld on at least 900mm, also weld on, say, 4'' bits of angle iron on this extension, it will help stabilize the posts in the concrete. If you're fitting a steel gate (which will have to be galvanized) get the pillars galvanized as well.

n.d.os

https://www.boards.ie/discussion/comment/120630617#Comment_120630617

Thanks for your message. This is the route I've decided to take as I am putting estate fencing around the property to replace what was there previously and architecturally brick pillars are not the route I wish to take. The posts formed part of the original fence that was built in the 90s, similar to what I've attached.

Yes, we will be welding on brackets in the future, and painting every few years is inevitable. It's unlikely the posts and fence will be galvanized but I will galvanize and paint the gate before it goes up. I will probably prime the posts with a zinc-based primer.

If the pillars don't work, we will use them somewhere else in the garden. I'd like to use them if possible and some posters above have given some good tips on how to do that.