Long Retaining wall for flower bed

[AdamAshworth1]

Hello, was wondering if any one could help?

I am going to build a raised garden bed retaining wall for a flower bed, as you can see from the picture the back of the wall will be 15 m long, the flowerbeds will be spilt into 3 sections of around 5 meters long. Each section will be 1 block higher and around 0.2 m wider as it goes down the garden. The first section will be 1.5 blocks tall, then 2.5 blocks then 3.5 blocks( it wont be a tall wall)

What i need to know is;

- will it be ok if i do this using single blocks or will it need to be 2 blocks thick? any advice on what type of block to use?

- Do i need expansion gaps, if so where would you put them?

thanks for the help

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Obviously on the view from above the black line indicates where the blocks will be!

 

[AdamAshworth1]

Anyone?

 

[Ionkontrol]

9 inch hollow concrete blocks is what I used.

 

[AdamAshworth1]

How long was your wall? Have you had any cracks after it has been done?

 

[r896neo]

Single 4 inch skin is fine

Standard 3.5N concrete blocks

You need at least one expansion joint in that length probably better with 2.

They would be least noticeable on the internal corners where the beds join each other.

To describe it better imagine looking from above. Build the centre one as a complete box and the outer 2 as large C's where they just stop short of joining the centre one.

You can simply leave a space but if your filling the beds then a bit of foam board and you can mastic over it or use a render stop bead.

 

[AdamAshworth1]

Thanks r896neo, made that easy to understand,

I have slightly changed the layout and just wanted to run 1 thing past you.

I am going to use 6or 9 inch 7n concrete blocks which i take is ok?

Also i have re-done the diagram, where i have put the expansion gap do i need brick ties inbetween the gap?

I take it that as i am using either 6 or 9 inch thick (have not decided yet) blocks i will not need pillars, it is only a low wall

thanks for your help.

 

[r896neo]

that looks fine.

no need for piers etc.

For such a low wall i wouldn't bother with ties across the gap. If you want to use foam board you obviously put it in as you build but if you just want to leave it clear a 10mm gap is plenty

 

[AdamAshworth1]

One last point i just thought of;

Where the expansion gap is, should the concete foundations have an expansion gap? Or should i do it as one piece?
I am putting the foundations down at about 250mm deep.

 

[r896neo]

no just make the foundation one piece.