How to build a 3m tall feature wall in a garden?

[Offcut]

This backyard's pool area has a 1.8m tall partition wall separating the pool area from the pump and pool equipment in the back corner and clothesline at the left side.

We are looking to remove most of this partition wall to open up the space to the fence line. There will be a new section of "partition" joining the left edge of the existing partition wall to the fence line so that the pool barrier remains intact as per regulations.

We'll remove the brick bench / storage area and want to replace the bamboo section with a 3m tall cement sheet wall that will run from the back corner of the block along the fence line to about in line with the back of the house. The brick fence will stay. Pool pump will be enclosed in a bench seat type unit and the entire area will have fake grass extended to cover. The new wall will be about nine metres long.

So, if you've persisted this far...

- how deep do I need to make the holes to support the posts that will support this new cement sheet wall?

- can I just use posts in the ground with concrete? A different type of footing?

- what if, when digging the holes I strike the concrete footings of the brick wall? Do I just bring the posts forward and sacrifice a bit of the garden depth?

- I'm assuming I shouldn't use many (if any?) attachments from the new wall into the brick fence especially as some of the existing supports (the brick storage thing) will be removed.

The wall that is currently behind the hard to see clothesline (pic with the paving) will be moved forward so will act as a brace as well.

Anything else I should be considering?

Thanks

[JacobZ]

Hi @Offcut,

Thank you for your question. Apologies for the delay in getting back to you.

The rule of thumb with posts is that one third the height out of the ground should be in the ground, so in your case to create a 3m tall feature wall, your posts will need to extend 1m into the earth. Posts with a total length of 4m are not always stocked in our stores, so I'd suggest speaking to the team at your local Bunning's Trade Desk about what is available from local suppliers. It is likely there will be posts that can be special ordered. Make sure they are H4 treated for in ground use.

Posts in concrete are your best option for this. I'd suggest coating the in-ground portion of the post in Gripset Betta 1L Waterproofing Membrane Bitumen Rubber for an additional layer of protection.

If you strike the concrete footing for the brick wall, you may be able to chip away some of it to create space for the post, but this risks weakening the brick wall's footing. It's probably best to just move the posts forward a little bit to avoid this.

You should try as much as possible to keep the structures separate. They can be tied together, but it should not be in a way where one supports the other.

Allow me to tag @TedBear, @ProjectPete, @Dave-1 and @Nailbag for their thoughts.

It sounds like a great project that I'm excited to see come to life.

Please let me know if you have any further questions.

Jacob

[Dave-1]

Good morning @Offcut 

I really like your idea for recovering that not so used space back  

I just had a look at what standard size cement sheets are, 2.4m ish. Depending on how you lay them (vertical or horizontal) you could get away with less cutting if you dont  stick to the 3m high fence line you mentioned. Or you could still have the height at 3m but the cement sheet drops to 600mm above the ground? 

Concreting posts in is what I would also be doing, tho I was going to say 800mm deep lol I would go eith the 1m that @JacobZ has recomendend. 

Is that new area lower then the pool level? If so by how much and are you going to fill it or leave it step down?

Striking the concrete of the support for the wall, if you do hit the foundation, how far out does it extend from the wall? if its only one spot or two maybe you could use stirrup styled support and bolt that to the foundation? Remember you shouldnt drill within 80mm ish of the edge of the foundation as you dont want to chance cracking it.

Dave

[Offcut]

Thanks @Dave-1 and @JacobZ  - you've pretty much confirmed what I was thinking!

For a span of about nine metres, how far apart should the posts be? 1.5m?

Existing height is 3m and that matches the neighbour's shed - so we'll need to maintain that height to hide the shed.

Ground is lower than pool side but will be infilled to create a level area.

Also thinking I probably need to use a 9mm or 10mm sheet - but if I frame it a little more a 6mm sheet should still be okay? Thinking about the weight - both once it's in place and just simply handling it.

Thanks for your replies.

Peter

[Dave-1]

Morning @Offcut 

1.5m would be good but factor in how you will be mounting the concrete sheets. If they are 1.2m then depending on how you work it resource wise. I generally sketch up my idea as an overall first, then go through and draw it again but with spatial measurements. After that is when I check out the resource sizing. 

As to the thickness of the sheet, the thinner the sheet the more you will need framing to keep it from developing a wave in it especially in the heat.

You could "step" up the privacy screen when its next to the shed to save resources and to break up the line of how it looks?

Filling in the area next to the pool. Please, pllleease dont fill with the broken rubble from the wall you are removing lol I curse the previous owners of my place as every trench Ive dug I have hit and then had to pull out builders rubble. Its a pain and then you or someone will need to get rid of it. I used my broken bits of builders rubble for gabion walls, either free standing ones or retaining styled ones. (could could use that next to your pool pump area even)

Handling the sheets, One thing you could do is install a bottom rail temporairly along the posts , dosnt have to be a full rail but piecs of timber screwed to the posts at the same level. This is to fold over the sheets to rest on, so you dont have the struggle of the weight  while attaching the sheets.

Looking forward to see the project unfold Oh and before you fill that area, think of lighting/power and also water pipes. I have extra installed in my yard for a "just in case" so I dont need to dig it all up again. Run conduits as its a minimal cost and saves loads of work down the track and if never used there is no issue.

Dave

[JacobZ]

Hi @Offcut,

It really depends on the cement sheet you're using.

If you select a material, they will have an installation guide that we should do our best to follow. As fibre cement sheets are generally used to clad homes, they are usually installed on a stud wall where there is a piece of timber available to attach to every 450mm. In your case, having posts with rails running between them, you won't have this many vertical supports, but we can look to replicate the screw pattern as closely as possible by spacing our posts and horizontal rails accordingly.

If you can advise what material you're planning to use, I can have a look through the installation manual and provide some advice. We should aim to replicate the prescribed installation method as closely as possible, but they are usually designed around the idea they are being installed on a house, not a fence. With this being said, you should note that fibre cement sheeting is not usually covered by a manufacturer's warranty when installed outside of its intended use. 

Once you let me know what material you'd like to use, I'm happy to assist further.

Jacob

[Offcut]

This Durascape one seems most practical - 3000 x 900mm #0710521 but seems to be out of stock. Weight 36kg - a 1200 wide sheet would be 48kg which increases complexity!

Maybe I could do posts at 1800 and rails at 450mm spacing vertically?

[Nailbag]

Hi @Offcut 

Highly recommend following the advice of both @JacobZ and @Dave-1 as they have already covered anything I could add to the conversation. The only thin g I could add is not be too concerned about even savings between the posts should you strike concrete footings in the holes you're digging. Trust me that the effort to break these up to remove them will be exhausting. Positioning the posts offset to these will not be ideal in being evenly spaced, but you will be the only one to know.

Nailbag

[Dave-1]

Evening @Offcut 

I would stick with smaller distance between posts as 1800mm carrying weight for years will end up sagging. Not worth cutting having to dig an extra hole or two as you will kick yourself in a couple of years. Thats a resonable weight to be supporting.

Dave