Is it necessary to concrete met posts?

[mrtomato]

Hi all.
I'm aiming to finally finish my fence during the good weather this week. My problem with previous attempts has been a lack of depth with my post foundations. The ground in my garden becomes saturated so easily that concrete just wobbles around in the earth and the whole fence becomes unstable. The other problem is wind; one puff and the fence shakes.

So, my question is should I concrete my met posts as well?

Many thanks.

 

[RedHerring2]

How high is your fence, and how deep are you putting your posts in?

 

[mrtomato]

Many thanks for your reply; much appreciated.

I'm using met posts with a 60cm spike depth and the fence is feather board at 1.8m high.

My plan is to space the posts approx 1.0m apart. I am also planning to hire a post borer from HSS to reach the required depth as the ground is quite difficult to dig out. I wasn't sure if such a narrow hole would fit both spike AND concrete.

 

[RedHerring2]

I'm a bit confused.
Normally you'd use met posts hammered in with timber posts bolted in the met post. I think it's fair to say that most pros don't like them.

If you're using concrete posts, why not concrete the post straight into a hole. Normally a third of the post goes in the ground. So for a 1.8m high fence you'd use a 2.4m post with 60mm in the ground.
Incidentally ensure the wooden fence is not in contact with the ground.

Why not invest in a hole digger, if you have a few of these to dig.
http://www.google.co.uk/products/ca...=X&ei=HnCsTabdLZKq8AOv1py5Ag&ved=0CC4Q8gIwAA#

 

[mrtomato]

My problem is that my soil is rocky. I've tried digging down but can only reach about 35cm. I had booked a hole borer for tomorrow, but thanks to the incompetence of HSS Hire I had to cancel that plan.

The tool you recommended probably won't help me get the depth I require.

Nevermind. Thanks again for your help.

 

[LooPrEvil]

I think RH meant to say put 0.6 metre in the ground, not 60mm!!

I would put nearer 0.8 metre in the ground, which is a third of the post length, which RH correctly states should be in the ground.

 

[LooPrEvil]

In rocky ground you sometimes need to use a spade and elbow grease to lift the rocks, and a cold chisel and hammer. If you can get the correct depth you will reap the benefits of a sturdy long lasting job.

 

[RedHerring2]

Yes, I meant 600mm, thanks to the Liverpool supporter for spotting and correcting that.

If the ground is so rocky a post hole borer probably wouldn't have managed anyway.

I find that a long bar, something about 1.5m long is an excellent tool for shifting the rocks out of the ground.
Like this:
http://www.google.co.uk/products/ca...=X&ei=gUStTbeUCZHA8QPDtZTzAQ&ved=0CC8Q8wIwBA#

If you install the posts correctly, you should get away with a post every 1.8m, so fewer posts to do.