so in Sep 05 I employed an extremely talented local builder (OK he was our youngest daughter's boyfriend but he is the best for miles around) to lay it for me...
We eventually established that is was the ground loop of the Heat Pump. It remains below freezing (typically -5C) from Jan to Mar and the area where the heave takes place is an under-ground water trap where the pipes are not insulated (insulating them would of course defeat the object!!!). The ground would not normally freeze more than 6 inches or so below the surface. But what to do about it?
Eventually Bev had a brain- wave. Why not build some decking over the patio - spanning the heave area? As a bonus, this would also free-up the slabs which could then be laid at the rear of the house where the original plan for some small areas of immaculate lawn had failed because of the shady conditions!!
All it needed was someone with a bit of time.... I had 23 days off in April - so guess what? See the Decking page!