How many blocks for retaining wall?

[DanielBall]

Hi guys,

Im planning on building a retaining wall in my garden.
My friend is going to dig the foundations
13M Long
0.225 Depth
0.450/.600 wide depending on hire machines bucket

He reckons ill need just under 2m3 of gen1 concrete

I plan for the wall to be 1.5m high, I'm thinking of laying the blocks on there flat for added strength/structure?

I think i have roughly 20 sqm2 of wall to build and I've read on here that theres 10 blocks to 1 sqm2

So if I'm laying on there flat ill need 400blocks? After a quick google theres 72 blocks on a pallet so should i get 5 packs to allow for any wastage??

Also is it worth putting a land drain in? or just come clean stone behind the wall

Thanks

 

[RonnyRaygun]

Your wall will need to be more than 215mm thick at the base if retaining 1500mm. Probably more like 440mm at least, or use hollowblocks with reinforcement or reinforced cavity.

You might also need a wider footing than 600mm else the foundation might start to rotate.

 

[DanielBall]

So would it be best to dig the footing 900mm wide? and lay a course of 18" block in the base then rack it up to 9" work?

Its all getting a bit confusing on the blockwork calculations side, its been a few years since I've done any i just want a long lasting wall

 

[theprinceofdarkness]

I am not sure of the 9" depth, that depends on the soil type, I would say that you need 9" into the subsoil. back filling behind the wall with gravel, just allows to water to lubricate your foundations and perhaps build up behind the wall. I would put in bleed holes to allow excess water to escape.
Frank