Garden wall footings in sand

[kingandy2nd]

I plan to build a double-skinned garden wall that will be around 80cm above ground level - basically high enough to discourage dogs from running onto our garden and to deter kids from walking on it.

Below top-soil the ground is really just sand (as we're near the dunes at the beach). Some research online seems to indicate a 1m deep foundation is needed, which seems a bit crazy to me. Any advice/wisdom on what to do, how to calculate a suitable foundation?

Given the sand, it feels like a wider foundation, rather than deep) would be better...but at the some time I'd like the wall to be as close to the pavement as possible as is the existing dwarf wall. Seems like all the other garden walls in the street butt up to the pavement too - do people just dig under the public path a bit to get the strip in?

Thanks for your help

 

[blup]

Can you pile some beams into the sand and build over the horizontal part

 

[Charlie George]

Most garden wall foundations are flush with the outer pavement, if you dig under the pavement you risk undermining it (especially with sand), also it will be near impossible to backfill fully unless you remove the paving, make it wider at back of wall, and use some mesh, depth wise? depends on ground a 350/400mm x 200mm foundation will be adequate, bear in mind its only a lowish garden wall.

 

[noseall]

I plan to build a double-skinned garden wall that will be around 80cm above ground level - basically high enough to discourage dogs from running onto our garden and to deter kids from walking on it.

Below top-soil the ground is really just sand (as we're near the dunes at the beach). Some research online seems to indicate a 1m deep foundation is needed, which seems a bit crazy to me. Any advice/wisdom on what to do, how to calculate a suitable foundation?

Given the sand, it feels like a wider foundation, rather than deep) would be better...but at the some time I'd like the wall to be as close to the pavement as possible as is the existing dwarf wall. Seems like all the other garden walls in the street butt up to the pavement too -

Sandy soil is ok to build upon as long as it is stable. A wider footprint rather than deeper is likely to offer the best results.

do people just dig under the public path a bit to get the strip in?

Yes.

 

[kingandy2nd]

Thanks for the feedback guys. Think I'll dig down a bit and then go wide and under the path a bit to get a decent spread

 

[cdbe]

Sprinkle a few bags of cement in your trench and hose it down before you do your footings - DIY ground stabilisation.

 

[Ivor Windybottom]

I'm typing this from a bungalow built on sand. It's definitely still here. But, built in the 1950s, it didn't have movement joints so has a few cracks.

Depending on the length of the wall, you should add some movement joints, through the wall and foundation slab, with slip ties across them. Put them at shorter than the normal (5m) intervals. Let it flex by putting the cracks in from the start, if you don't then you'll get them added later and they won't be straight or pretty.

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• Debonding sleeve lets masonry expand or contract for better usage• Maximum durability and stability Stainless steel strip tie designed to be used with a Debonding Sleeve in a movement joint in brickwork or blockwork.The movement ties restrain masonry against lateral wind loads whilst allowing...

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[Mr Chibs]

I recently knocked down a wall 8.5m long, couple of small piers, wall around 900mm tall, single brick, footing was 150mm thick one end and a stingy 30mm thick at the other end, wall had stood for years until it was replaced, on sandy soil. Think you'll be good.

 

[stuart45]

Wide strip foundations normally need reinforcement to be really effective. The weight of a wall is transferred down from it's edge at around 45° downwards, so even when made a lot wider it can still crack from that point.

 

[kingandy2nd]

Thanks guys. All very useful

 

[phatboy]

We live on a sand dune. The footings for the extension are (mostly) 600w x 300d, with mesh.

When I built that, I did the garden block wall footing 200w x 150d. It's still standing, and is considerably more than was there on the previous wall from the 50s which was fine - it was more like a thick mortar bed than a foundation!

 

[Ivor Windybottom]

Sand is actually a good base for a reasonably lightweight structure. It's inert, i.e. there are no worms moving it around or bits of biological matter decomposing and sinking. Clay is also inert but expands and contracts more than sand as it gets wet then dry.

As long as you don't overload it, sand will happily sit there as long as you like. Although running water could be an issue if it physically rinses the sand away.

Our place is a bungalow. I'd hesitate at building a two-storey or higher building on the stuff, perhaps OK with a raft foundation though.

 

[Dereekoo]

Read Cl 2E3 of Doc A building regs and use your finger