# Forum Home Renovation Retaining Walls  Footing size for small besser walls

## Moondog55

Not really a retaining wall so much as a tall raised garden bed.
I want to go 3 or 4 besser blocks high and roughly 2400 * 900 using full blocks ( and corner blocks I 'spose) but this will be a productive vegie and herb garden and will be filled with our local clay soil.
Will I need to refer to the builders guide and use a proper footing dug all the way down to the stable marl layer( 1100 down )  or is a 450 deep * 450 wide trench going to be OK for 20 years or so??
If I need to I will fill the hollow blocks with grouting and use reo bars

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## PeteV

hey moondog,
best bet, 450mm deep, 300 wide, 3 bar trench mesh top and bottom. put dowels every 600mm to 100mm below top of wall height and corefill. use 2001 blocks, these are 390l 190w and 190h. you might wanna doctor your measurements a little to make it work.... 2390 * 790 or 2390 * 990. corner blocks aren't required for these blocks as they work half bond on the corners. you could also look at getting some caps for it, bag it all up and it'll look a million bucks! hope this helps!

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## Moondog55

That is a lot better than having to go all the way down to the marl, sounds strong enough to be a machine gun pit.

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## PeteV

yeah, it probably is still a little over-engineered, but it's better to err on the side of caution... particularly when dealing with vege gardens, as people are generally inclined to constantly water them putting added weight on the walls...

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## cherub65

With besser retaining wall footings wider is better than deeper. Engineer footing would be approx 700mm wide for 800mm high x 250mm thick with a 450mm toe.

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## Moondog55

Please explain the "TOE" i'm not familiar with that usage.
I really don't want tha footings wider than than the garden bed, herbs need free draining soil and we need to drain through the soil not through the walls

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## PeteV

cherub, although you are correct when you are referring to a retaining wall, a garden box doesn't really come into the same equation... this is because there isn't the same load, as it isn't retaining as much. for example. moondogs wall will be retaining at best half the volume of the box (because there is effectively a retaining wall either side) which is being strengthened by four corners. in contrast, a normal retaining wall has the full load of the volume behind it. i'm not sure that i explained this clearly, but i'm sure moondog will have no dramas with these footings on a flower box. moondog, toe is the very bottom of the trench on a strip footing. hope this helps!

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## Moondog55

Having just quickly done a costing on footings and bricks I may have to rethink and use 70mm LOSP pine instead, did want the finish to match our (Possible ) new wall treatment but pennies are pennies at the moment. Thanks Pete 4 "Toe" I know what it is called now LOL I learn something new every day

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