Ground swell - Advice sought to stop ground swell

[greatbrew]

I moved in a new build in May 2016. Since moving in there has been a significant amount of ground swell in the rear garden.
I am about to take up the paving laid by the builder and replace with a larger path. However, I am concerned about the ground swell and what I may be able to do to prevent it reoccurring.
To give you an idea, outside the back door the path has risen 45mm over a length of 900mm.
Suggestions so far:-
1/ Remove 150mm depth, lay 100mm reinforced concrete then pave on top.
2/ Remove 250mm depth, lay 200mm type 1 (packing down in 75mm layers), then pave on top.
Has anyone any advice/ideas to offer?

[Tony McC]

Before determining what remedial strategy might be more appropriate, I'd want to know what is causing this uplift.

Have you had any investigatory work done?

[greatbrew]

Tony, thanks for responding.
The swell and shrinkage is around the rear of our home. One thought is ground disturbance during piling of foundations. I have also been told that the clay in this area of Essex (SS5) suffers with swelling and shrinking. My neighbours have a similar issue.
No investigation carried out yet, just thought i'd try Brew cabin to see if anyone has had similar experience and if there experience gave a timeline of when it settles (hopefully it will).

[Tony McC]

I know quite a few paving installers in that that part of the country and about half of them will only lay over a concrete base rather than a flexible sub-base because of the problems with ground movement.

I'm not sure how bad it is on your plot, but maybe a concrete base is the better option in this case.