Concrete Base for Summerhouse

Hi,

I have a few questions regarding a concrete base we are about to have done for a summerhouse and seating area if anyone can help it would be greatly appreciated

The area for the pad is 8.4m x 6.3m, this area was initially higher than the rest of the garden and we have taken off the excess soil so it now sits level with the rest of the garden.

1) when having the concrete done, instead of removing the timber formwork can we keep this in place forever, as we will paint this to create a wooden trim effect with paving going on top, will this cause problems in the future (if the wood soaks up water will this affect the concrete in the long run?)

2) instead of excavating further down, are we able to put the layer of compressed hardcore above this level ground (50mm compressed) assuming we will keep the formwork in place

3) as it is sitting above firm ground already, will 50mm compressed TYPE1 MOT, 150mm ready mix concrete with A193 metal reinforcement be strong enough for the timber summerhouse and seating area (moderately heavy use)

Thank you

 

Cheers for the reply @Abrickie, timber will be pressure treated and will also give it a once over with anti rot

 

Cheers @stevie22, we got rid of around 3/4 inches of top soil which has now made it level with the ground level, or do we need to get rid of more top soil?

 

@stevie22 top man