How to cover gap underneath Colorbond fence?

[HarrySan]

Hi guys,

I need professional opinions on how to cover the gap underneath the fence?

I know there is a straight forward way of putting sleepers underneath but to do that I need to remove the panels and everything which is a big job nonetheless great one.

 

Are there other options? I’m planning to cover the gap so it gives me a neat n tidy looking wall. Also I want to plant veggies in the foot or so area between the fence and the retaining wall.

Thank you heaps!

[EricL]

Hello @HarrySan 

Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about covering the gap underneath your Colorbond fence.

There is no need to disassemble your fence when putting in the 200 x 50mm Sleeper H4 Sienna MicroPro 2.4m. I suggest digging a channel underneath your fence so that you can slot the sleeper directly into the gap. You also have the option of using concrete and composite sleepers. To keep the sleeper in place you can use Jack 450mm Heavy Duty Steel Sleeper Peg Flat Stake or the Jack 450mm Sleeper Peg Steel Corner Stake along with the Jack 450mm Sleeper Peg Steel Flat Stake. Once the pegs are driven into place you can then screw the supports into the sleeper.

The 200 x 50mm Sleeper H4 Sienna MicroPro 2.4m uses a copper-based preservative which makes it safe to use in playgrounds and vegetable gardens. 

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

Eric

[HarrySan]

Hi Eric,

thank you so much for the reply, I understand how to push in sleepers aster digging a channel but where does the pegs fits in?

into the ground and screws into sleepers?

Thank You

[JacobZ]

Hi @HarrySan,

Yes, what you have said is correct. 

You would drive the pegs into the ground with a hammer flush with the face of the sleeper then use 40mm Galvanised Timber Screws to attach the timber sleeper to the peg.

The peg will anchor the sleeper in place when it is screwed in.

Let me know if you have any further questions.

Jacob

[MyaBrien]

Hi Jacob

I have a similar retaining wall and Colorbond fencing situation as the photo in the original question above (similar retaining wall height, mostly 700 m high with smaller portion of it going up to 1 m high). My rear boundary is about 300 mm from the back of the retaining wall, and I would like to put a Colorbond fence with a sleeper underneath at the boundary. But all the Colorbond fence contractors that have come out to quote just want to install the fence on top of the retaining wall (developer left fence brackets on top). They are saying the retaining wall is too close to the boundary to dig posts, but we've seen it done all the time around the area and other estates. Is there a way to use the existing fence brackets to reinforce posts at the boundary? Should I be approaching retaining wall companies? I've got a fencing company coming to quote that also does retaining walls, and I'll be very surprised if they also say they won't dig posts.

I don't know where the gravel above the retaining wall drain would usually start, and the developer won't give me the retaining wall design or company details of who installed it. Their response was I should just be using the fence brackets on top. Attached was the approved retaining wall design I pulled up from developer's application from the Moreton Bay council site. I am on the proposed lot side (the lower land).

Thanks

Mya

[JacobZ]

Hi @MyaBrien,

Welcome to the Bunnings Workshop community, it is fantastic to have you with us.

Unfortunately, you couldn't safely install fence posts along the actual property boundary without damaging or in some way affecting the drainage, which is an essential component of any retaining wall.

Generally, fence posts will have concrete foundations that are 300mm in diameter and, depending on the height of the fence, anywhere from 600-1200mm deep. If the posts were to be installed directly along the fence line, then half of this concrete foundation would protrude into this 300mm section of drainage gravel and would likely hit the agi pipe at the base of the trench.

The issue you'll find is that installing these concrete posts would considerably alter the drainage characteristics of the retaining wall, and anyone installing that fence would assume legal liability if the retaining wall were to fail because of this alteration. This is likely the main reason you are having contractors refuse to build the fence in that way. Unfortunately, unless you were able to find a contractor who is willing to accept that liability, then I doubt you'll have much luck getting someone to build your fence along the surveyed property line.

Unfortunately, I am unaware of a way that you could safely use the fence post connection cleats on top of the retaining wall to build a fence along the property line.

It may be a pain, but I can't really see a way that you could avoid having the fence run on top of the retaining wall.

Allow me to tag our knowledgeable members @Dave-1 and @Nailbag to see if they have any thoughts about the situation or advice they could offer.

Jacob

[Dave-1]

Good Evening @MyaBrien 

The retaining wall system that was installed on the blocks look like it has been built purposfully to carry a fence plus allow drainage of the same walls. It does make sense that installers wouldnt want to change that as it complicates who is responsible for failures down the track. 

If we had a photo of the retaining wall and it showing your boundary line we maybe be able to come up with other ideas. The problemis my imagination keeps bumping up against the boundary line itself. The retaining wall sounds liek it is the boundary line even if the drawings ssuggest its a little further away. You will gain back the slice on the other side if it has the same style retaining wall maybe? A photo would help us out picturing it for sure.

Dave

[MyaBrien]

Hi Dave and Jacob

Thanks for the reply. Our boundary is definitely behind the retaining wall and looks exactly like the photo originally posted above. The registered survey plan confirms this and surveyors pegs are behind the retaining wall. Wouldn't a recommendation to the original poster to dig a channel or drive pegs in behind the retaining wall also affect the retaining wall drainage? 

Some of the fence contractors also told us we can't put a 1.8 m high fence panel on top of the retaining wall due to increased height from natural ground. We would need to apply to council for approval and because the retaining wall isn't on the boundary, we would solely own and be responsible for the fence and the backfill/drainage we wouldn't have access to.

Council originally approved to have the retaining wall on the boundary, but the developer moved the retaining wall and drainage onto our side so that the retaining wall and backfill/drainage would not affect the neighbouring high side from their use of their land (i.e. the retaining wall only benefits our side), but then the developer also stated in the land contract the fence doesn't have to be on the retaining wall.

I really wish retaining walls like this were done with the fencing at the same time, or fencing before retaining wall.

Thanks

Mya