Setting posts for 5-bar gate - concrete, earth, rocks?

[adamr7747]

Hi All,

I'm planning on installing a double 5-bar gate, with 175mm square softwood posts, set around a metre deep (assuming I can dig that far!). I've seen mixed advice online about how to set them. The "default" approach seems to be to set them in concrete, but a significant minority of people note that this encourages rot in the post. The alternative seems to be to ram the earth (or stones?) hard back in around the posts. Does anyone have experience of this? Will it be sturdy/rigid enough to support the gate?

Thanks,
Adam

 

[Scally-Ho]

How you' set' the posts will depend on the ground makeup and how densely it is already compacted.

 

[adamr7747]

Thanks. It's very compact, heavy, rocky subsoil.

 

[Scally-Ho]

As it's rocky and therefore presumed to be reasonably well drained, heavy well rammed clinker would make a good setting material, but these days it's finding a supplier. Well rammed earth with rubble could work, too much gate slamming might weaken the hold, so you might have to set with a good cement content concrete and vibrated to compact, thus eliminating any air pockets. Trapped air will start and enhance any rotting process.
I part OP, 2 parts sand and 4 parts aggregate. OR, a known grade of 3/4" all in ballast. The 1:2:4 mix, when set and cured, will ensure the post will not be influenced by any ground water. If the ground is thought to be in any way contaminated, substitute SR cement for the OP.

 

[bernardgreen]

How heavy and what size are the gates ?

It could be that if the gates are heavy then the posts might need more than a simple hole to keep them vertical.

 

[adamr7747]

I haven't bought the gates yet but they'd just be bog standard 3m softwood gates. I guess ~50kg? Bernard, what are the brown areas in your drawing? I was planning on just having isolated holes for the posts.

The ground does not drain well (though I'm hoping to improve that - see other recent post!). I guess it's some kind of clay/shale mix.

 

[bernardgreen]

Adam

The brown areas are concrete just below ground level. It was a single pour ( no joins in the concrete )

The posts had initially been set in simple holes by the company that installed the gates.
Within weeks one gate was dragging on the ground due to the post having started to lean.

 

[adamr7747]

Eeek, I wasn't planning on 6m of concrete! :/