Do I really need to use MOT Type 3 as Gravel drive sub-base

[nigel88]

I've got a 160m2 area which I am going to be turning in to a gravel driveway.

There is currently no drainage in the area and I don't really want to be installing drainage. The area is surrounded by the house, garage and public road, so I can't really slope it in a certain direction to aid drainage.

Upon plenty of research, it is clear that MOT Type 3 is the best sub-base to use in this situation as it is free draining. Whereas Type 1, depending where you look, some people consider to be permeable and others don't. It certainly isn't going to be as permeable as Type 3.

My issue with using MOT Type 3 is the increased depth required. With Type 1 I would install 150mm compacted, the Type 3 appears to require 200-225mm compacted as it has poorer load bearing qualities than Type 1. It isn't just the cost of buying extra sub-base, its the fact that I would have to remove an extra 12m3 of sub-grade, which I'd then need to pay to get rid of, plus it's a tight site so it then becomes awkward moving around and stocking piling the soil, etc. Also, if Type 3 is quite open graded, I'm concerned that then over time some of the top layer may get picked up and combined with the gravel on top.

I'm not looking to shortcut anything, but I do have a tendency to massively over engineer things sometimes to be on the safe side. I've read a few places where people have used Type 1 as a sub-base and had no problems whatsoever with drainage. I know there are an awful lot of gravel driveways near me and I have never noticed issues with flooding, and I am sure most of then don't have a Type 3 sub-base. I'm in a sandy soil area so the sub-grade is well draining.

So what is the consensus, should I be using a Type 3 sub-base in this situation or do you think I'd be fine with a Type 1?

[lutonlagerlout]

I would go type 1 all the way
or crushed concrete if you can find a decent supplier
cheers LLL