How much concrete to use with metal fence/trellis supports?

[vonsworld]

Hello

I'd like to erect a heavy trellis with 70mm wooden posts using concreted-in metal post supports. Please see the photo below.

The trellis will be 7ft high and although it is quite heavy, since it is full of holes, it will not catch the wind in the same way as a regular fence.

My question is, what size of hole and how much concrete would you recommend when setting these type of post supports?

Thanks

 

[ktuludays]

Given that you need access to the bolt for tightening I'd leave this accessible just above ground.

Dig your hole accordingly to depth and keep it nice and small in diameter, post hole diggers would be best for a nice neat hole.

A 2ft hole normally requires 1 bag of postcrete.

 

[JohnD]

You can place them with the entire socket above the ground, so the timber is not in contact with damp soil. This will slow rot.

 

[ktuludays]

You can place them with the entire socket above the ground, so the timber is not in contact with damp soil. This will slow rot.

But wouldn't give a very good fixing for the post.

 

[conny]

Rule of thumb for post fixing is 1/3 post height should be buried. It's perfectly acceptable to have the socket above ground to enable you to tighten the bolts up fully and if the post does go slack, because of shrinkage when it dries out, you can then slacken the bolts and put some thin shim pads in before re-tightening.
So if your post is going to be 7' high you will need a Metpost around 2'-6" into the ground.
Make sure the post is not slack in the holder. It's much better if you need to shave the bottom couple of inches to ram it into the holder than to try and pack out a slack one.

 

[ktuludays]

Rule of thumb for post fixing is 1/3 post height should be buried. It's perfectly acceptable to have the socket above ground to enable you to tighten the bolts up fully and if the post does go slack, because of shrinkage when it dries out, you can then slacken the bolts and put some thin shim pads in before re-tightening.
So if your post is going to be 7' high you will need a Metpost around 2'-6" into the ground.
Make sure the post is not slack in the holder. It's much better if you need to shave the bottom couple of inches to ram it into the holder than to try and pack out a slack one.

Ooer...there's nothing worse than having to pack out a slack one.

 

[conny]