Concrete slab for oak porch

[Newtohere15]

Hi guys,

Will be building a oak porch onto the front of the house in a few months time, the porch will have a 2ft cobble dwarf wall with the roof bolted into the house and oak supporting post to the front. I'm not new to porches or carpentry but I am to building regs and foundations. The porche will be 2m in length and 1m in depth. It is not within 2m of a boundary.

There is a history of subsidance so guidance on the slab would be appreated.

My question is how deep should The slab be?
Should a dpm be used even if the porch is open fronted?
How deep should the hardcore be under the slab?

Many thanks in advance guys

 

[cjard]

Til you find firm ground
It's probably not necessary but for the cost of it being pennies I'd put one in in case you ever want it to be close fronted
6 inches, whackered, sand blinded to protect the Dpm

 

[Newtohere15]

Hi thanks for the reply, you say till you find firm ground, does that mean if it was say 1m till firm ground what depth hardcore would I lay and what depth concrete would I lay. Eg, 600mm hardcore and 400mm concrete or visversa?
Also how long would it take for a concrete slab to dry and harden if it was 400mm?
Last question I promise what percentage balast to cement would you use for the slab and do you add any additive to your mixes?

Thanks in advance.