How can we put a fence above an old stone wall with solid foundations?


The wall is 400 yrs old and we can't really attach the posts to it. We started to dig holes for 5 posts but about 1/1.5 ft down is a stone foundation which we presume is also acting as a level for the wall as the ground is sloped. It comes out 10" into the flower bed and to put the posts further in would eat into the garden and look really odd. The wall is waist height and the fence has to be 1m above the wall (slats starting above the wall) to take the overall height to 2m so it's going to be top heavy.

We have come up with the following ideas but would appreciate any advice/input:

  • take a pneumatic drill to the foundations to create deeper holes
  • Use the holes we have as they are and add angled supports out into the ground
  • Sink planters into concrete in the existing holes and concrete the fence posts into these

* An updated option is to bolt metal fence feet to the foundations, secure the posts into the feet then concrete over the whole lot

That's about it but surely this is something that has happened before?

Many thanks!

  6 answers
  • Flipturn Flipturn on Jun 21, 2021

    What depth of property do you have to work with behind the stone wall?

    How level is the land behind the stone wall?

    • Fi Fi on Jun 21, 2021

      Hi thank you for replying. The land behind the wall belongs to another property so we are unable to put anything in there unfortunately :-( Their land is much more level than ours but they say the stone foundations do the same thing at their side which is why we think they were laid first to create a level base.

  • on Jun 21, 2021

    How tall will your fence be? What is it made of? Is there frost where you are? The reason I ask - if it low and not very heavy you may be able to get away with post spikes which require much less digging.

    • Fi Fi on Jun 21, 2021

      Hi, thanks for the reply. The fence will be 2m tall (1m above the wall) and made of timber posts and horizontal timber boards which we were intending to attach from the top of the wall upwards. We do get frosts in the winter maybe to minus 10 max.

  • GrandmasHouseDIY GrandmasHouseDIY on Jun 21, 2021

    Hi Fi the first thing I thought of was that instead of digging the post down you could put them on the old foundation directly in front of (and against) the wall. To do this you would build square concrete frames around the bottoms of your posts and fill them with concrete essentially concreting them to your old wall. You could leave the wood "frames" too and use their tops as little planters.

    • See 1 previous
    • GrandmasHouseDIY GrandmasHouseDIY on Jun 21, 2021

      Hi Fi, anchor bolts would definitely help make it all more secure. I think if you do the planter idea where the "backside" of the planter box that's against the wall is open to the wall so the concrete adheres to it you would be OK.

  • Cheryl A Cheryl A on Jun 21, 2021

    attach the posts and boards to the wall in front of it not on top of it and it should work fine

    • Fi Fi on Jun 21, 2021

      Hi Cheryl, thanks for the reply. Unfortunately given the age and condition of the wall we've been advised against attaching anything to it. The mortar is very sparse in a lot of places and a few stones have loosened however it is still standing and not ready to fall just yet.

  • Betsy Betsy on Jun 21, 2021

    Hi Fi: (why does that make me smile? ) Is it possible to put additional stones, even fake ones, on top of the existing wall to make it taller? I believe we're talking about 3 feet, right? You might be able to replace the missing or old mortar to make the wall a bit sturdier to accept the additional weight. However, if I were to do this, I'd sort of lean them backwards to keep them from toppling.

    Good luck

  • Kathy Gunter Law Kathy Gunter Law on Jun 22, 2021

    You can attach by using L shaped brackets. Attach to the posts and then use masonry screws to attach to the wall/foundation.

    • See 1 previous
    • Kathy Gunter Law Kathy Gunter Law on Jun 22, 2021

      That's what I was thinking would be easier. If it was the wall, you could use a bracket but since you can't I guess the foundation it is.

Your comment...