Help with gate posts installation to avoid moving?

[WelderJohn]

Hi Guys,

Looking for a bit of advice on how to install gate posts for large, heavy gates.

I have been making and installing a lot of smaller fabrications, path gates, small driveway gates etc.

I have started doing some larger fabrications and have been asked to do some big 6m wide x 7ft high gates, made from 50mm box section + 16mm infills/decor. (so 3m per leaf)

The gate really has some weight in it and I am apprehensive of how to install the gate without the weight of it pulling the post over.

The problem is that there is no wall/house to bolt onto for extra support, and due to boundary issues I cannot install a 45 degree or similar stay/support arm.

So, the only place I can increase the strength of the setup is either under the ground or by upgrading the post. I was also thinking of adding some underground support coming off the post at 90 degrees and concrete that whole section in as well.

Logic tells me that if I put enough concrete/post mix in the ground it would counterbalance the heavy gate leaf. Also I thought if you put a post deep enough and thick enough it would be impossible for it to deflect at the top with the weight of the gate.

Someone had said a general rule they used was 1/3 underground to 2/3 above ground, so 2m above, 1m below.


Obviously if you put 25 bags of postmix in a large enough hole then it would not go anywhere, however, I am trying to get a balance between proper engineering and overkill!

I would like to make it as secure as possible but do not want to do a full extra days work digging huge underground trenches to support the post when its maybe not necessary or the best option.


Anyone got any tips on best way to install this?


Thanks!

 

[WorkshopChris]

Hi and welcome,
What size/ type of section was you thinking of using for the post.
Will your 50mm box be ok for a 3m span.

 

[ajmoore1]

50mm box not big enough for a 3m gate.

 

[brightspark]

no need to dig massive holes for posts depending on the ground. if its clay just dig a deep ish narrow hole drop it in and a bag of post crete. if its soft ground u will have to go wide and deep

 

[Migmac]

Never hung gates that size or weight but when I put gate posts in or strainers in I have as much under the ground as I have above the ground. All the spoil that comes out the hole goes back in, tamp it down hard and the post never moves

 

[steve_s]

I made some gate around that size a life time ago for a factory entrance thay were made from 6" channel with 25mm rebar uprights and weighed around 1/2 ton each from memory, I used a "I" beam as an upright with a plate welded on the bottom and then a brick pier built round it that was 40 odd years ago and thay stayed till the site was redeveloped a few year ago

The company was Welbeck international on River road Barking for any of you Essex boys you my have seen them

 

[armalites]

I made these from 150x150, angle iron on the bottom helped them stand up and stop them pulling out.i put the mix in dry rammed in down and added water in layers. It meant they were absolutely solid and I was able to hang the gate the following day.They were sunk 24 inches in the ground.Due to the feet I was able to use ballast to get them level and as you can see the alignment had to 100% for the bolt. You can't see it in the picture but I have a tube let into the latch post so a chain can go through. It's not physically possible to remove the gate unless it's open. These were built to suit a standard galv farm gate

 

[armalites]

 

[JohnH]

I always used to dig a trench between the post holes, and then place several rebars between and around the posts then set them in concrete. Stops them spreading and drooping.

 

[octo0072000]

old heavy gates used to be sat on a bearing cup taking the weight of the gate some even had a wheel and a steel track so the gate could never droop when opening

http://www.fhbrundle.co.uk/products/051526570__BOTTOM_PIVOT_HINGE_WITH_BALL_BEARINGS