Example: A houses interior air temp is a comfortable 23oC and outdoors is 6oC with relative humidity at 55%.
The dew point in this scenario will be 12oC (www.dpcalc.org).
The point at which your wall is creating condensation at 12oC should still be at a point within the insulation.
However as building designers in Newcastle we find because cold is creeping in (i.e. heat escaping) through the thermally unbroken slab, the point at which your slab is 12oC may be 1m into your home and causing condensation to form.