Foundation for a Shed

I need to build a foundation for a 11 X 8 Plastic shed. I don't plan to put anything particularly heavy in it. However I do plan to put a lawn mower and my bikes in there. I plan to concrete in place a ground archer for the bikes. The shed is in a closed if garden with 7 foot high fence which backs onto a school.

Originally looking at a video on YouTube I was going to dig a foundation and put down the MOT Type 1 and compact it then mix the concrete my self in a mixer and pour it my self.

However I had a quote and the guy said it doesn't need a foundation and you can put a plastic foundation down. I assume he means the plastic grid foundation squares you can buy ( I have read they are very hard to get level)

Any tips please?

 

I'd go with your original concrete plan if I were you- those plastic things cost about the same as concrete & won't be much of a base for your ground anchor. Regarding the ground anchor, get one you can cast into the floor (rather than one relying on rawlbolts) while you're at it. With the slab, don't go much bigger than the shed (if you do you'll get water going under the shed)

 

Don't forget to factor in how long it will take to cure at this time of year. Depending on how wet your mix is it could take 2-3h - possibly more. i.e. Get cracking at first light, but be prepared for finishing off after dark - sort out some outdoor lighting etc.

 

I put up one of the keter sheds a few years ago. I already had a base but it was very un-level. The sheds use a plastic base and the sections sit in the base plate if the slab is too out it just won't assemble.
I cast a new base on top of existing went from like 30mm to nothing poured concrete even that was like 1/2 ton of concrete. Lucky I had mixer to hand. For concrete I always get bags of ballast much easier than bulk bags to put in mixer.
For a fresh base I would dig out say 9" soil, lay a dpm or old rubble bags in bottom then broken up hardcore 4-5" inches then poured concrete. For one of my other shed slabs this one was 1.75 tons of concrete I poured it 95% then the last couple of mixes I used the white cement gives top of slab a nice light colouring akin to Spanish countries rather than our dirty dark grey.