Deck footing

[TheSandman69]

I'm building a deck that's attached to my house (50cm high at it's highest point). I'd like it to last as long as possible so instead of burying the uprights in the ground, I'm looking at putting them in shoes (pictured) which go 20cm into cubes of concrete, 30cm deep and 30cm across, and none of the wood will be in the ground.
Does this sound solid? I know the usual method recommended goes ~50cm into the ground, but then why are those concrete elephant feet things acceptable?

 

[Dereekoo]

Seems expensive way to do it but will achieve your desired aims

 

[John D v2.0]

Yes as long as no wood in ground contact I will be good.
I'm doing similar but just dig down to subsoil, lay a 300x300x150d foundation and then brick pier up to joist level then sit the joist directly on top. Probably a bit more labour then yours.
Make sure you use decent durable timber, in theory softwood needs to be bs8417 use class 3 or 4, but good luck getting hold of that. Most places haven't heard of it.

 

[JohnD]

You can also use concrete spurs in the ground, bolting your wooden frame to them.

The load in decking is almost all vertical, unlike a fence that will blow over, so you don't need to fill the post holes with a lot of concrete.