Gateposts for heavy iron gates

[clifford1]

I have bought a pair of ornamental drive gates, spanning an opening of about 10 feet. Each gate is about 5 feet wide, and around 8 feet high, weighing 180 Kg.

There are no gateposts at present, and I want to build, or have built, a pair of nice solid pillars in reclaimed brick. Each gate will sit on a ball-bearing support at the bottom, bolted at ground level to a projecting part of the concrete footings. There is a strap hinge at about 6 foot off the ground, with a V-shaped bracket to be cemented into the pillar at the appropriate level as construction progresses.

My questions are:

What volume/size of foundations will I need? I presume the easiest is to dig a large hole and fill it with concrete to ground level, and then build the brickwork on that base?

What width of pillar should I specify? Two brick-lengths looks very slender, 2.5 or even 3 bricks looks chunkier. How can I calculate what weight a pillar of given dimensions will support, hanging at that height?

Any advice or experience would be much appreciated. Probably I will just hand the job to a builder, but I'd like to know in advance what sort of principles and dimensions are involved.

 

[JohnD]

Plain brick pillars will break or lean (a substantial wall is better).

Go for steel stanchions set in concrete, well painted against rust, and build the brickwork around them.

A good. tip to prevent gateposts leaning is to pour an RC sill between the two foundations so they balance each other. This even works with ordinary garden gates. Pour it all in one hit and protect it from drying out for two weeks or more so it gains stength and hardness.

 

[xsealuser]

I work next door to a gate manufacturer who makes hardwood gates. They are the heaviest type of gate you can get. He always says that a brick pillar must be filled evenly with concrete if you are to stand any chance of it not collapsing under the weight of the gates. Also, he recommends using a timber clad steel when needing to match the gate to the posts. I've also seen an automation option which sits underground with the two posts revealed. It doesnt take long to install and takes the weight of almost any gates.

Hope this helps!

 

[clifford1]

I've also seen an automation option which sits underground with the two posts revealed. It doesnt take long to install and takes the weight of almost any gates.

I'm not quite sure what you mean by that - is it like a buried RSJ with verticals welded on, projecting through the brick pillars?

I like the idea of linking the two pillars somehow. Having a continuous concrete foundation across the drive rather than two separate ones sounds good.
But of course the force on the pillar will be at 90 degrees when the gate is opened, so any reinforcing below ground would have to work equally over a range of directions, not just across the path.

I suppose driving in a vertical pile would obviate the need for very much foundation at all, just a pad to sit the brickwork on?

 

[catlad]

Square holes not round will work better.

 

[ivixor]

Yep, I'd let the steels form the structural elements, then you can clad in brick with no worries.

Once a suitable bit of steel (RSJ?) is sunk into about a cubic metre of concrete each (not necessarily as a cube), it's not going anywhere. You can then bolt the gate supports securely onto the steel.

Try to build the brick pillar around and independent of the steel to allow for flexing - leave a gap between the brick and the post. Don't forget to put some conduit in for lighting.

 

[xsealuser]

I've also seen an automation option which sits underground with the two posts revealed. It doesnt take long to install and takes the weight of almost any gates.

I'm not quite sure what you mean by that - is it like a buried RSJ with verticals welded on, projecting through the brick pillars?

I like the idea of linking the two pillars somehow. Having a continuous concrete foundation across the drive rather than two separate ones sounds good.
But of course the force on the pillar will be at 90 degrees when the gate is opened, so any reinforcing below ground would have to work equally over a range of directions, not just across the path.

I suppose driving in a vertical pile would obviate the need for very much foundation at all, just a pad to sit the brickwork on?

Its essentially a U shaped frame with automation built in - the website i've seen it on it ironwoodgates.co.uk but I think there are a few variations about. Once its fitted you can clad or build around the frame as you want to.

If your gates are free hanging without automation, as long as your pillars are well built with a foundation of sorts and they are filled solidly and evenly with concrete then you wont get any movement. Connecting the 2 piers with some sort of foundation is probably over kill but would indeed provide the maximum resistance to any possible movement.

 

[clifford1]

Many thanks. I'll put these points to the builder.

 

[clifford1]

Update:

We've just had a builder round to advise and give a quote. We have used him before, he specialises in traditional buildings, stone and brick, and have found him reasonable and trustworthy.

He advises that the pillars need to be 3-bricks square to provide the stability, with two foundations of concrete 600 mm cube, linked by a trench, all filled in one go.
Interestingly, he advises against using a single steel post, for risk of rust cracking the brickwork, but favours perhaps 6 or 8 vertical steels as used for reinforced concrete, hammered into the ground below the foundations as far as possible, and then the hollow inside the bricks filled with concrete, creating a reinforced concrete post inside the brickwork.

 

[Norcon]

As long as your happy the hangers can be fixed securely to the brickwork or a hanger design allowing them to submerge within the inner concrete.

I'd be happier with a central staunchion and hangers welded in place and gates hung before any brickwork commences.
And the void then filled with concrete anyway.

Re-bar can rust too!

A pillar built from lego would likely collapse under pressure from the concrete. Head pressure from 3m of concrete is colossal.
All depends on how its poured obviously and what securings are in place.

 

[clifford1]

Many thanks. I'll put all these points to the builder and see what he says.

I believe the gates will have a tradional V-hanger for the upper hinge, to be buried inside the brickwork and into the concrete core.
The lower pivot departs from the traditional simple spigot in an iron plate, and will have a sealed roller thrust bearing on a plate bolted to the projecting horizontal surface of the concrete foundation - in this case the continuous concrete beam across the drive.
Also the lower and upper hinges will be adjustable to some extent, to correct minor errors of alignment or initial movement.