How to install a fence on a retaining wall?

[bengroll]

I've recently had some retaining walls installed and now am hoping to install some "temporary" fencing along the top of the LOWER level (see below) primarily to deter the family from getting to close. Options I've seen include basic picket fencing (metal or wooden https://www.bunnings.com.au/rapidfence-2200-x-41-x-1200mm-black-blade-picket-fence-panel_p0438319), wire fencing and posts, or even glass pool-side-type fencing. I can't dig behind the wall: we have SUPER hard rock and digging and concreting posts is not an option, plus there isn't much space anymore). Plus I plan on removing the fence in a few years once family has grown up enough to stay away from the edges.

Can I simply bolt posts into the top of the wall? Would it be better to bolt to the front? There's only 50-100mm space on the rear of the wall to bolt to the back.

I'd love some ideas, or tips, or further advice.

[EricL]

Hello @bengroll 

If you are after temporary fencing, I propose putting some 70 x 35mm Outdoor Framing MGP10 H3 Treated Pine 2.4m right in front of the retaining wall itself. I suggest using Zenith 14G x 75mm Galvanised Type 17 Batten Bugle Head Timber Screws - 25 Pack to anchor it in place. As for the fence itself, I suggest using Saxon 105cm x 20m Wire Dog Mesh which can be nailed into the timber posts.

This type of fencing is light but sturdy. It will not put a lot of strain on your retaining wall and the holes drilled into it can be patched and covered up in the future. It is strong enough to deter both pets and family members from climbing or entering the top part of your retaining wall. 

Let me call on our experienced members @Dave-1 and @TedBear for their recommendations.

If you have any other questions we can help with, please let us know.

Eric

[bengroll]

G'day @EricL 

Thanks for that.

Where are you saying to install the framing timber? Upright against the front of the wall, and then attached the mesh between several of the posts?

Something like this?

Thanks

[EricL]

Hi @bengroll 

You've hit it spot on! Your render illustrates exactly what I'm trying to suggest. This will save you from having to find an anchoring system for the top of the retaining wall and you won't have to worry about any applied weight. It's easy to install, plus you can even disguise it by putting EDEN 1 x 3m Natural Bamboo Screening in front of the wire mesh to give it a nice natural look.

If you need further assistance, please let us know.

Eric

[Dave-1]

Good Morning @bengroll 

Man, @EricL's solution matches pretty much up to mine and your sketch is bang on  

Seriously I cant think of anything more to add and thats a first! lol

Love retaining walls! And yours looks like a nice one! Going into rock or solid clay is no fun I must admit.

Dave

[bengroll]

Thanks again @EricL and @Dave-1 

The project has had a new "condition". The other half (ie: the "boss") has said they're not a fan of having posts sitting in front of the wall, and ruining the view (their words not mine lol).

Is there an option to install fencing directly to the top of the wall? Bolting upright posts: something like https://www.bunnings.com.au/peak-1000mm-silver-aluminium-deck-balustrade-mid-post_p1142464: onto the top sleeper and then running fencing between them, either the mesh referenced earlier or something different? Would most likely end up costing more BUT aesthetics are priceless (as is a happy partner lol).

[Dave-1]

Morning @bengroll 

The reason I didnt suggest that was the rotational stresses of if someone leans on the fence being focussed on a small width of timber. and it would splinter and fail. You could put down a timber cap with multiple screws into the topmost piece and then the fence on top as that would distribute the forces. How much space do you have behind the wall before you hit the rock ? I was considering teh 690mm ground screws that bunnings sells, Groundscrew Stirrup  if there is minimal space but enough to screw down into the ground behind your wall. Or a Steel angle mucj like an upside down L that you can screw to the backside and over the top of the timber to attach a post to.

Dave

[EricL]

Hi @bengroll 

Great minds truly think alike, I was going to suggest the same thing what @Dave-1 recommended. My next suggestion was to put a timber cap on top of your retaining wall. You can then build on top of it to create custom fence. Once you've built a frame you can use a host of panels to create a nice fence. For example, you can put the Matrix Panel inside the frame to create a patterned fence.

I've placed a sample sketch below to give you an idea of how you can build it. It won't look as rudimentary as plain posts and you can paint it to make it look even better.

In regards to the Peak 1000mm Silver Aluminium Deck Balustrade Mid Post, it's possible to install it on the retaining wall but you'll need at least a 140mm cap over it as the footing of the post is at 100mm.

If you have any other questions we canhelp with, please let us know.

Eric

[bengroll]

So this design: I like @EricL ! Now being a near-total newb, what type of wood would you recommend? And screws/bolts? Thanks

[Jason]

Hi @bengroll,

Just a heads-up that @EricL won't be on the site for a few days. We are currently expecting him back on Friday. Apologies for the delay. Please let us know if you question is urgent and we can tag other community members to assist. 

Jason