Erecting fence on concrete hardstanding

matty_hunt

Hi. I wonder if you guys could offers some advice or share experience. I have a concrete hardstanding that the car used to be on. I would like to cut that area in half by erecting a six foot high fence across the concrete. It runs from a rendered garage wall to a low block garden wall on the other side. Distance about three meters, with a gate mounted on post by garage wall. Ive considered a couple of fencing types but my concern is the posts. I had thought of using the bolt-down met-post type of thing like these http://www.diy.com/nav/garden/fencing-paving-decking/fencing/fixings___tools/Bolt-Down-Fence-Post-Support-W-100mm-x-D-100mm-Pack-of-2-11507782 with shield anchor bolts.
Using two, about two meters apart so they are away from the edge of the slab with cant rails overhanging to the edge. My concern, given that posts are supposed to be two foot in the ground, are these two bolt-downs going to be strong enough to hold the entire fence since the wooden post only sits about five inches into them?
Any thoughts much appreciated.
Thanks

NewtoDIY

I erected a 7m long wooden fence under similar circumstances. The posts really ought to be sufficiently under ground to withstand high winds. It doesn't matter that they are mounted in concrete which is rigid - if you have very high posts with high winds and not much "anchoring" them underground, then there is a much higher chance that they will prematurely break.


I had my builders dig down into the concrete about 60cm, then fill the first inch or two with gravel to allow drainage, and then fit the posts surrounded by concrete. Where the post meets the ground level, the concrete is tapered downwards to allow rainwater to run away from the posts.
Breaking up the concrete is a nasty job for a pro with the right tools.

warmhands.coldheart

Couple of things to question and points to make


1. How thick is the concrete on the hardstanding? If its a good thick slab then I can't see why you couldn't use this type of thing but a 6ft solid fence might be a bit high if the are is susceptible to high winds as commented above, maybe a lower fence or one with gaps in the boards...
2. If a thin slab I'd cut hole on concrete and dig down as NewtoDIY has said, however I'd go with concrete posts if doing that as wooden ones will rot over time...

matty_hunt

Thank you. Im not sure how thick the concrete is. Its quite long and has no cracks so assumed it to be 4-6" at least. I did think of cutting holes in it to sink in posts but I like the temporary nature of the bolt-downs as in the future I can see the full hard standing area may be required again.

sk240

Hi,

You will need to break up the concrete for each post, and dig down to the correct depth, you will probably need a breaker from a hire place.

I have used the bold down ones before, if the anchors are not man enough they will just pull out, and any swaying due to the wind will actually break the welds on the bolt down pads!

Theres only really one way to do it unfortunately, i have learned from my previous mistakes.

matty_hunt

Thanks sk240. I will give the bolt-downs a miss! I had not thought of the welds breaking.
Many thanks all.

mttylad

Yes forget the metposts, its going to be hard work but you can break your way down - go down 2 foot.

I was glad I paid someone to do it for me.