Steel or aluminium post for RapidFence gate?

Question

Hi, i have purchased a steel RapidFence 1200 x 900mm Black Garden Picket Gate. Specs say the gate is 7.6kg. I was thinking of using a flanged aluminium post which would be fixed to concrete path with dynabolts but I am wondering if I should use a steel post instead as aluminium may not be strong enough? Thanks

Matt

MitchellMc · Answer

Hi @Matty_G,

I think a steel post would probably work in your situation, it's just not the most robust solution when it's only secured to a concrete slab with a base plate. For normal, light-duty use it should be fine, but you do need to consider the loads a gate can place on the post. For example, if a child were to hang off the gate while it's open, there's a risk of the leverage pulling the masonry fixings out of the concrete.

I think an aluminium post would be a little too flexible for this application, so if you're choosing between the two, I'd definitely lean towards steel.

The only real alternative, if you wanted a much stronger installation, would be to cut out a section of the concrete and concrete a larger galvanised steel post into the ground, such as this

https://www.bunnings.com.au/australian-handyman-supplies-75-x-75mm-x-2-4m-galvanised-steel-fence-post_p1140442

or even a

https://www.bunnings.com.au/australian-handyman-supplies-89-x-89mm-90-x-90-x-3-0m-galvanised-steel-fence-post_p1140455

. That would provide far greater resistance to the twisting forces created by the gate.

Mitchell

Matty_G · Answer

thanks Mitchell. Unfortunately I can’t fix the post to anything. I guess I could go for a lighter gate? Any other suggestions? Thanks

MitchellMc · Answer

Welcome to the Bunnings Workshop community, @Matty_G. It's great to have you join us, and many thanks for your question.

Flanged posts fixed to concrete with masonry anchors generally have limited resistance to sideways loading. They work best when the post is also tied back to another post with a fence panel or connected to a solid structure such as a wall. A gate hanging from a standalone post places considerable leverage on both the post and the concrete fixings each time it opens, closes or catches the wind.

If the post will be completely standalone, I would be looking at a steel post rather than an aluminium one. Even then, the fixings and the condition and thickness of the concrete will be important because a substantial amount of force will be transferred into them.

An aluminium post could potentially be used if it is adequately braced or connected back to another structure, which would prevent it from flexing. Without that support, it is unlikely to provide the rigidity needed for a gate of this size and weight.

Please let me know if you have any questions.

Mitchell