Timber fence on top of stone wall - construction method

[DaveH]

I'm shortly going to start on my permanent boundary wall so that the long suffering neighbours that sold me the plot can have their garden back!

 

The boundary will be a natural stone wall approx 600mm tall on good concrete footings onto which I would like to put a wooden fence of around 1.5m. Any advice on how best to construct this? I was considering building some galvanised box sections or Easy Grip type post shoes into the cavity to accept some 75 or 100mm fence posts before the coping goes on. I can also concrete fill the cavity for additional strength if required. Also considering whether to use pre-manufactured fence panels or construct the whole thing from scratch.

[lizzie]

I have mine between pillars...we filled the cavity with concrete.  Didnt use posts in the end used brackets on the pillars, no good if you dont have pillars though.

[Cpd]

Your definitely going to need to make sure that whatever you do is going to withstand wind. I would be looking at a tying your post holders to the concrete footing to give it the strength it needs. A post holding foot of some kind firmly attached to the concrete would be good as it will make maintenance much easier should you need to replace a post or section of fence.  I would pour a footing with tie bars sticking up in the centre and then build a shuttered section that will be the centre of the wall and fill with concrete, build your stone faces on both sides, attach your post feet, build the coping and then plonk your fence on top and attach to the post feet. 

[lizzie]

I'm in a very windy location high up on top of exposed ridge thats why we went for pillars and metal brackets for the cross timbers and used hit and miss for fencing so wind could go through otherwise it would be blown down regularly.

[Jeremy Harris]

The top of our retaining wall was 215mm wide hollow concrete block, with the hollows filled with concrete and the face of the wall rendered.  I opted to bolt metal post holders down to the top of the wall with thunderbolts and fit the fence posts in them.  The fence sits about a metre above the wall and seems pretty robust.  We have rails and close boarding on one side of the posts and rails and trellis on the other side.

[Ferdinand]

As ever, the one thing you do not want is wood in contact with either the ground or concrete. If you are doing that, then use Postsavers.

 

 My usual way for more durable fences is to use concrete fence repair spurs, which come with bolt holes to attach posts, set into the ground. Then attach vertical posts, and horizantals to that, and then your facing verticals. Here that would give tryouts something structurally separate from your wall, which may or may not be beneficial.

 

On occasion I have bolted posts to the back of the wall; I would not do that in this situation.

 

I would also make it permeable to some extent.

 

I note that your total height is over the the normal 2m limit.

 

Ferdinand

 

 

 

Edited March 12, 2019 by Ferdinand

[DaveH]

Thanks for all the replies.

 

After a discussion with the builder and throwing some ideas around I think I will make some steel box section vertical posts with a plate welded to the base which will be bolted directly to the foundations (possibly galvanised or just painted). They will have some tabs welded on to attach the horizontal timbers to and then the vertical timbers screwed to that. The dwarf wall will be built around the steels so that the posts are in the cavity and we will cut the copings to go around the steels. I'm favouring double sided, offset vertical timbers to give privacy but also allow airflow to reduce any potential wind loading.

[Jeremy Harris]

You can buy ready made concrete in/cast in post bases, like these:

 

https://www.toolstation.com/post-base/p82691

 

https://www.toolstation.com/cast-in-post-shoe/p64644