How to cap gap between retaining wall & fence?

[ehsan_rd]

Hi,

I’m looking for advice on how to cap the gap between my retaining wall and the surrounding fences. The retaining wall is U-shaped, with an old timber fence on one side, a new timber fence on the other, and a Colorbond fence at the back.

• Side sections are about 3 m long
• Back section is about 16 m
• Depth behind the retaining wall varies from 400–900 mm
• The gap between the wall and the fences ranges from 200–300 mm

I don’t want to fill or compact the whole depth — I just want to cap the top of the gap so it looks neat and prevents debris, leaves, or pests from getting in.

What is the best way to cap this long, uneven gap? (e.g., timber sleepers laid across, metal flashing). Thank You!

 

 

 

 

[JacobZ · Accepted solution]

Hi @ehsan_rd,

Honestly, installing separate posts would be the best option as it would mean you don't have to drill into the sleepers in any way. If you are happy to put in the work, then I would definitely encourage this solution.

You could install posts at the midpoint of the sleepers, as there will be no concrete there to deal with, then run the rails between those posts.

Please don't hesitate to ask questions; that is why we are here.

Let me know if there is anything else I can assist with.

Jacob

[ehsan_rd]

Hi @JacobZ,

Can you suggest what type of posts can I purchase from Bunnings for this job?

And, we still need to add rail to support decking board on both edges. Am I right?

Thank You.

[Dave-1]

Good Afternoon @ehsan_rd 

Instead of the extra posts, how about a short timber piece that sits on top of the concrete sleeper and then screwed to the new timber rail. Then the "capping" 140mm merbau can get screwed to that?

And there is "never" too many questions We all ask questions and its the only way to learn

Dave

[JacobZ]

Hi @ehsan_rd,

You can use anything that is H4-treated. These 90 x 90mm 2.4m Post F7 H4 Treated Pine Premium KD would work.

Yes, you would still need a rail on both edges unless you simply sit the edge on top of the retaining wall side and don't screw it down.

Jacob

[ehsan_rd]

Hi @Dave-1,

May I ask you to draw sketch? I'm not sure if I fully understand. Appreciated.

Thank You.

Ehsan

[Dave-1]

Good afternoon @ehsan_rd 

Give me a sec, will do when I finish eating my lunch

Dave

[Dave-1]

Good Afternoon @ehsan_rd 

So the Dark blue crossbeams are the extra bits I was refering to. One end rests on the concrete sleeper (its not going anywhere) and the other is screwed to the new rail you still need to install. You will be able to cover the whole gap this way as a bonus. Using 2 of 140mm Merbau it should fit easily across the width of the gap.

You could also paint the underside of the short crossbeams with a tar substance to help keep them in resonable condition.

Would love to see a project created if you go the route of these timber caps. There are a lot of instance that people have similar to yours and it would help future questions.

Dave

[ehsan_rd]

Hi @Dave-1,

I like this idea! I’ll probably need to screw on another thin piece of timber to fill the small gap between the Merbau and the concrete sleeper on the grass side. Once I finish the project, I’ll take a photo and post it here.

Thank You.

Ehsan