How to build a timber sleeper garden bed to protect the fence?

[losty]

We are looking to replace the hardie fence with a new colourbond which will be built with 2 x plinths (150mm each and 1.8 m panels, giving us a total finished height of 1.9 - 2.0 m. The new fence is yet to be built. Once the color bond fence is up, we are looking to build a garden bed using H4 sleepers as per video - Build a garden bed with seat (youtube.com).

Since the garden bed in the front will be 450mm high, what's the best material we can use that can be attached to the fence or installed on the ground to stop the soil touching the fence and slowly damaging it.  Another plinth or is there a more suitable option. 

Existing FenceGarden Bed Design

[EricL]

Hello @losty 

Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about building a raised garden bed with seating near your fence.

You'll notice on the guide How to build a decorative raised garden bed with seating by @Adam_W that he built the bed with sleepers at the front and the sides. I suggest adding an extra wall at the back using the same materials and installation technique used at the front. This will make the the garden bed independent and not linked to the fence. I suggest building the garden bed at least 100 mm away from the Colorbond fence. This will make the fence independent of the garden bed and there will be no need to worry about soil contamination.

The only reason Adam built the bed in such a manner was because he was building against rocks. If there were no rocks at the back, it's highly likely that he would have built it as a rectangle.

Let me call on our experienced members @Dave-1 1 and @Nailbag for their suggestions.

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

Eric

[Dave-1]

Evening @losty 

Yeah my thoughts are exactly along the lines of @EricL's Even to the spacing away from the fence.

I really dont like the idea of fences carrying any load at all, having the garden bed freestanding makes it a lot stronger in my head and no issues with anything pushing the fence out of alignment.

You might loose a little depth of garden bed but long term it will be worth its loss

Dave

[Nailbag]

Hi @losty reinforcing both @EricL and @Dave-1 comments to keep the garden beds separated from the new fence. Instead use dual height 2100mm x 50mm sleepers (trimmed at 8m) to make joint garden beds the length of the fence and positioned adjacent. Line the inside with builders plastic to prevent the timber decay and seepage through the layer. Use a stapler to fix the top fold 10mm below the top edge.

Regards, Nailbag

[losty]

Thank you @EricL , @Dave-1 , @Nailbag for your response and suggestions. Taking into consideration, we have decided to go ahead with a limestone wall as per sketch below. Let me know if you see any issue with the revised plan. 

Also, i am looking to attach a composite decking board as a capping on top of limestone wall (example photo below with a bullnose, but i am looking to use composite board with an outdoor light strip underneath). Could you please suggest the best method to attach the composite decking board to the limestone top (150mm wide). 

[Dave-1]

Afternoon @losty 

I dont see any problems with your design. I havnt done any limestone wall before. With the lighting there will be varius ways depending on the actual lighting that you want to use. You will need to factor in that the lighting will be next to a wet area so will need to stand up to that.

When i was looking at your distances and the pool photo I did note that your new wall is going to be a resonable way up your fence. I know in NSW there is a pool law that says you cannot have climbable areas next to pool fences. It might be an idea to check out your local council rulings as I do know a bunch of new rules have come into effect this year.

Dave

[EricL]

Hello @losty 

The design looks great, but I agree with @Dave-1 to check with your local council regarding pool fencing laws before starting. My number one recommendation is to seal the back of the limestone wall to prevent water from passing through the limestone and sealing the front to stop mould infestation from happening. This will also make cleaning the limestone much easier as a strong sealer will prevent mould and mildew from infesting the surface of the limestone.

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

Eric

[Nailbag]

Hi @losty 

Your revised plan looks great. Since your limestone wall is on the pool side of the boundary fence, there shouldn't be any issues with pool fence reg's. It's keeping kids from getting in not out thats the issue. But since you intend to build a substantial wall at great expense, I would still touch base with council to check the wall itself is within regs.

Regarding fixing the composite boards, I would run a twisted line of liquid nails then use Ankascrews 15mm in from each side edge spaced at 500mm to ensure the boards don't lift, twist or bow.

Nailbag

[losty]

@Nailbag Thank you for your great advice. I have checked with the council and its all ok. Much Appreciated. 

[Nailbag]

Nice work @losty 👌