FRENCH DRAINS 

Good conservation grade french drains are one of the most significant factors in keeping the inside of your building warm and dry. But be very careful not to undermine the footings when you excavate or you will cause subsidence in your walls, this can take 10-20 years to manifest, but it will happen if you don't follow proper specifications.  A conservation grade drain may cost significantly more to install but it is far more than your standard trench with a few chippings in it and is considerably more effective in reducing damp. Keep hard impermeable surfaces away from the walls.  Much of what is attributed to rising damp is penetrating moisture and condensation and its these conservation specifications that take these factors into the equation.   See notes on Damp