Decking foundations

Had a quick look online http://www.planhelp.com/public/104.cfm and it seems that the lowest supporting load for bare ground is just under 10 tonnes/square metre, (table here actually shows 2000 pounds/sq foot as it is american) so your 0.3m x 0.3m pad is good for about 900kg. Prob more. Don't know how many pads you have but assuming a few, I think you should be fine without digging out but let's see what the pro's say.

 

unless the top soil was laid down or dug up recently it will be firm enough to take the weight. But slabs need to be well placed if they take some weight. I don't use slabs as it suits me to dig out a spot and set the post into that with concrete.

 

If the ground is firm I set in concrete breeze blocks too rest the joists on, stronger than paving slabs, but easier than casting concrete.

 

To be honest I've only ever used posts with concrete but if you didn't want to do that I would use breeze blocks like Phil says. Paving slabs might be absolutely fine but if you know you are going to be putting a serious weight on it I wouldn't risk the hassle of having to re do it all. Good luck

 

What is the soil like in your garden?

 

Sorry I meant in terms of firmness. Basically you want it to be as compact as possible so if it is loose you would want to get a roller and compact it down. Also you are going to want to put down a weed barrier as it's so close to the ground. You could do it with slabs if that's what you feel most comfortable with and to be honest it will prob be fine. You just want to make sure the ground is as solid as possible. It isn't like you're far off the ground if anything was to collapse anyway

 

No worries. You said yourself you aren't a newbie so when you are laying it out you can always just strengthen extra bits where you see fit. It will all work out fine. Good luck and enjoy the Jacuzzi!!

 

foundations are for houses, the idea being to get down to the subsoil, where its stronger. you won't need to do that. besides the whole deck isn't likely to suddenly fall into the bowls of the earth due to its own weight.

if the top soil can be dug out with your own hands its loose and you will need to get down deeper to find something solid, and it probably won't be that deep. if you need to use a fork or spade to get into the top soil its firm enough, and you can put down a slab and build on that.