Decking posts in solid chalk

[jacko555]

Am building a deck, ground is solid chalk.

How deep should I sink the posts? It's not that that tough to dig out, apart from the occasional lump of flint.

Decking is on a gradual slope, floor level to around 50cm on the far end.

Should I still go 600 per support, or can I reduce a bit. If so, how low?

Cheers

 

[jacko555]

No thoughts?

 

[scbk]

600 deep posts would be overkill on the top side of the slope, but probably needed at the bottom

 

[Dereekoo]

What is your purpose in digging down i.e. to find firm ground for bearing support or to provide stability against sway. Imagine putting a table on your patio, no need to dig down to prevent sinking and only need to dig down 50mm to prevent table moving, depth to prevent table swaying depends on rigidity of table legs connection to table top, solid connection no sway, pin jointed connection lots of sway.